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HALF HOURS WITH
THE LOWER ANIMALS

PROTOZOANS, SPONGES, CORALS, SHELLS
INSECTS, AND CRUSTACEANS

BY

CHARLES FREDERICK HOLDER

AUTHOR OF "ELEMENTS OF ZOÖLOGY," "STORIES OF ANIMAL LIFE," "LIFE OF LOUIS AGASSIZ," ETC.

NEW YORK ᠅ CINCINNATI ᠅ CHICAGO

AMERICAN BOOK COMPANY

Copyright, 1905, by

CHARLES F. HOLDER.

Entered at Stationers' Hall, London.

LOWER ANIMALS.

W. P. 2

PREFACE

At the present day education is not complete without definite courses of nature study. We are living in an age of strenuous business life and activity, where the best equipped students along the various lines secure the best positions. Time was when zoölogy, botany, and kindred nature studies were classed with music and the so-called dead languages, and were taken up as incidentals or were employed in "mind training"; but to-day there are a thousand branches of trade and commerce which require knowledge that can be obtained only through nature study.

It is not necessary that the student, unless he intends to be a teacher of science or a professional naturalist, should be able to pass examinations in the abstruse classification of animals or delve into difficult anatomical studies. What the average student needs is a broad and general idea of animal life, its great divisions, and notably the relationship of the lower animals to man in an economic sense, the geographical distribution of animals, etc. It is vastly more important for the coming lumber merchant to know the relationship which forests bear to the water supply, and to have a general idea of forestry and the trees which make forests, than to be able to recite a long formula of classification or analysis, of value only to the advanced student or specialist. The future merchant who is to deal in alpaca, leather, dye, skins, hair, bone products, shell, pearl, lac, animal food products, ivory, whalebone, guano, feathers, and countless other articles derived from animals is but poorly equipped for the struggle for business supremacy if he is not prepared by nature study, nature readings, and other practical instruction along these lines.

It is believed to-day by those who have given the subject the closest attention that the initial move of the teacher should be to call the attention of the child to the beauties of nature, the works of the Infinite, and thus early inculcate a habit of observation. The toys of the kindergarten should be fruits, flowers, shrubs, trees, pebbles, and vistas of mountains, hills, lakes, and streams, and nature study in some form should be continuous in school life.

In the following readings the story of lower animal life has been presented on broad lines, divested of technicality, and at almost every step supplemented by forceful and explanatory illustrations as ocular aids to the reader. The subject has been divested of dry detail, and I have introduced notes and incidents, the results of personal observation and investigation in various lands and seas, and have given attention to the often neglected fauna of the Pacific coast as well as that of other regions.

While the volume is a supplementary reader, the matter is so arranged that it can be used by the teacher as a text-book, and the pupil who undertakes the various "half-hour readings" of this series will have covered in the main the ground of the ordinary text-book for intermediate grades in the form of readings. In a word, I have endeavored to make this volume a popular combined review and supplemental reader on the lower forms of animal life from the Amœba to the insects inclusive, and the series to follow will present the entire subject of animal life or zoölogy, voluminously illustrated, on a similar plan.

CHARLES F. HOLDER.

Pasadena, California.

CONTENTS

HALF HOURS WITH

THE LOWER ANIMALS

PROTOZOANS, SPONGES, CORALS, SHELLS, INSECTS, AND CRUSTACEANS

I. INHABITANTS OF A DROP OF WATER

The most unobserving stroller through the forest or by the seashore can not fail to be impressed by the abundance and variety of animal life; yet the forms visible to the naked eye really constitute but a fraction of the vast horde which makes up what we call life.

In the year 1901 a strange phenomenon appeared off the coast of southern California. The ocean assumed a reddish muddy hue which was traced for four hundred miles up the coast and from one to twenty miles offshore; hence, at a conservative estimate, the reddish color occupied a space of ten thousand square miles. At night it assumed a greenish light, and when the wind rose and formed whitecaps, each became a blaze of light, and the ocean as far as the eye could reach was converted into a mass of seeming flame. The sands of the beach gave out flashes of light when touched; the footsteps of dog or man on the sands left an imprint of vivid light, and figures made on the sands with a finger or stick stood out in lines of light. Ten thousand square miles of phosphorescent light; ten thousand square miles of living beings, each so minute that it was almost if not quite invisible to the human eye. Who could estimate the individuals in one square mile, one square foot, or even a drop of this reddish water? This illustrates the fact that the greater number of the earth's population are unseen, even though not invisible to the unaided eye.

These minute animals are as interesting as the larger forms. Equipped with a microscope, we are prepared to explore the regions in which they live and observe their habits. A favorite hunting ground for this small game is some long-standing water in which plants have been growing. Placing some of this, with the green scraping of the glass, on the slide, we shall soon make out, moving mysteriously along, something which resembles the white of an egg, an atom of slime or jelly. Now it stops and throws out parts of itself which seem to fuse together again; now it is long, now short and compact, again circular. You almost believe it is a mere atom of slime, yet it is an animal which eats and lives its life cycle in a drop of water, one of the lowest of all animals.

It is called Amœba (Fig. 1), and although it is hardly a hundredth of an inch in diameter, yet if we devote some time to it we shall find that it is a very remarkable animal. Thus if it wishes to move in any given direction, a portion of the body becomes a seeming leg and protrudes in that direction, the rest of the body following, drawn along in some mysterious manner. If it wishes to eat, it is not obliged to twist around to bring the food or victims opposite the mouth, as a mouth forms there and then; the Amœba merely glides around it and covers it up.

We may even notice a difference in the parts. Thus the center calls to mind ground glass; it is blurred or granular, while around the edges is a little border which is transparent, like ordinary window glass. So the Amœba is a minute mass of jelly inclosed in a layer a little clearer.

Fig. 1.—Amœba proteus, with the pseudopodia (false feet) protruded, enlarged 200 diameters (after Leidy): n, nucleus; c, contractile vesicle; v, one of the larger food-vacuoles; en, the granular endosarc; ec, the transparent ectosarc; a, cell of an Alga taken in as food (other cells of the same Alga are obliquely shaded).]

Floating in the granular portion is seen a minute round body called the nucleus, clearer than the fluid in which it rests, and not far away another clear, circular body, which from time to time contracts or sometimes disappears in a marvelous fashion, but always returns. This is called the contracting vesicle, and here our discoveries end, so far as organs and structure are concerned, as these are nearly all that have been found; yet the Amœba eats, doubtless sleeps, and grows.

Fig. 2.—Amœba eating: Pv, contracting vesicle.]

We may watch it at its dinner. When a victim is found, an animal smaller than itself, out shoots a little cape or extension from the clear rim, creeping slowly up the side of the animal; and if we watch very closely, we shall see the thicker portion of the Amœba, that which calls to mind ground glass, running or flowing into it. Then another false foot, as it is called, slowly creeps out on the opposite side and joins its companion, more of the ground-glass matter slides or pours into this, filling it out, and, presto! the two arms merge one into the other. The victim has been swallowed and is now being digested [(Fig. 2, d)].

Fig. 3.—Amœba separating.]

That this minute atom has its likes and dislikes is evident, for if the food is too large, or not to its taste, it retracts, or even draws away from it after it has swallowed it. The shells of its victim, if it has them, are rejected in a manner equally simple; the Amœba flows away from them. Jar it with a needle point and it contracts, showing that it can be irritated. At times the body is seen to divide and two Amœbæ are formed (Fig. 3), each of which has a separate existence from then on. Such is one of the lowest of all animals. It is made up of but a single cell. All the members of the other great branches of the animal kingdom and the higher plants are made up of many cells; hence we see that the Amœba is the simplest and lowest of all animals.

Fig. 4.—Ciliated Infusoria: A, Bursaria; B, Nyctotherus; C, Amphileptus; D, Ceratium; E, Monosiga; f, flagellum; n, nucleus; c, contractile vesicle.

In looking into our drop of water our attention has perhaps been distracted by other animals. In point of fact, it is very difficult to keep the eye on this mass of slime in its slow movements, for about it, over it, and constantly bumping into it are countless other forms whose motions convey the impression that life to them is very active. The most numerous are little objects (Fig. 4) resembling hats or bells, which go rushing along, bumping aimlessly into all others, and always in a hurry. Around the edge of the bell or hat are numerous hairs (cilia) which are really locomotive organs by which the little animals whirl themselves along. Near them we see numbers of similar objects, each one forming the cup of a seeming flower, each having a long stem. These are Bell Animalcules (Fig. 5) or Vorticellæ, among the most beautiful and graceful of all the minute animals, but much higher in the scale of life, as they have a permanent mouth and form. Among them, swimming rapidly, comes a giant by contrast, the Paramœcium (Fig. 6) or Slipper Animalcule, so called from its resemblance to a slipper. It, too, is a higher form than Amœba, as it has a permanent shape; yet in other ways it is as simple as Amœba. The Paramœcium has a marvelous array of oars which cover its body. Under the glass they look like eyelashes or whips, and by their rapid movements they drive the animal along. On the side is the mouth opening, into which the animal fans minute animals, and they can be seen swept along by the irresistible current, caught by the mouth if desirable, or tossed off if not to the taste of the wonderful living slipper. After glancing at the drop of water for a few moments the observer is convinced that here is a world in itself, with a population growing, increasing, developing, devouring its prey, and in such multitudes that the mind can not grasp the figures.

Fig. 5.—A, Stentor; B, Vaginicola; C, group of Vorticellæ; D, bud of Vorticella.

Fig. 6.—Paramœcium: e, mouth; v, contracting vacuoles.

Fig. 7.—Nummulites.

If the reader visits Egypt and climbs the pyramids, he will be impressed by these the greatest works of mankind. If a small portion of the stone from which they are constructed is placed under the glass, it will be found in many instances made up almost entirely of beautiful shells (Fig. 7). These are the shells of an amœba-like animal known as a Nummulite, which lived millions of years ago, and whose fossil remains formed the stone from which the early Egyptians in turn built the great piles or monuments of their kings. Man is powerful, but in this instance one of the most insignificant of animals made his work possible. These shells are of great beauty and variety (Fig. 8). Many are perforated, and through the minute holes are seen the false feet of the Amœba reaching out for food. They illustrate the boundless resources of nature, and suggest that the very lowest of creatures are not too insignificant to be dressed in most beautiful garbs, as all these forms vie with one another in the delicacy of their designs (Fig. 9) and the grace of their shapes. Some of these shelled forms are giants two inches across. All these minute shells perform a marvelous work in building up the crust of the earth, forming the bottom of deep seas and the platforms of coral reefs. The chalk cliffs of England are composed of shells of unestimated millions (Fig. 10), which were once dropped upon the bottom of a deep sea and piled upward until some were crushed into a shapeless mass of lime, others retained their shapes (Fig. 11); and all, by some convulsion, were afterward lifted high into the air.

Fig. 8.—Flint-shelled Radiolarian.

Fig. 9.—Flint-shelled Polycystina.

Fig. 10.—Foraminifera from Atlantic ooze.

The entire ocean is as thickly populated with these atoms as the drop of fresh water. The shelled forms are as constantly dying, the shells falling or sinking in a continual rain of shells upon the bottom, piling up eternally. Who shall estimate their countless numbers? It is believed that these minute shells are as abundant down to a depth of six hundred feet as they are at the surface. There are more than sixteen tons of limy shells floating in the uppermost one hundred fathoms of every square mile of the ocean. These facts convey an idea of one way in which the earth is growing—increasing in size but not in weight, as these delicate creatures merely secrete the carbonate of lime which forms their shells. They take it from the surrounding water of which it has been a part.

Fig. 11.—Section of English chalk cliff. Highly magnified. Bottom of an ancient sea.

It would be of great interest to learn exactly how these humble creatures take lime from the water and produce shells of such marvelous beauty: to learn why one is of lime and others, like the Radiolarians, are of silica; why some live at the surface and are free swimmers, while others creep about in the ooze. When the deep-sea explorers first began to dredge, they found over vast areas a peculiar mud or ooze, and investigation showed that it was formed almost entirely of the shells of a certain minute shell maker, from which it was named the Globigerina ooze. Finding these vast banks or beds of mud at this depth is suggestive that the deepest seas may yet be filled by the dropping of this invisible rain; but as the average depth of the ocean is nearly if not quite three miles, many centuries must pass before this will be accomplished.

Fig. 12.—Noctiluca. Highly magnified.

The marvelous phosphorescent light previously described came from a minute armored form known as Peridinium, but even this is exceeded by the glories of a little monad called Noctiluca (Fig. 12). It is a giant of the tribe, and is visible to the naked eye, being almost as large as the head of a pin, and resembling a currant in shape. It has a single hairlike organ or lash, supposed to be a locomotive organ, by which it whirls itself through the water. Of all the light givers of the sea this is the most common, some of its species being found in every sea, and where they are, it is necessary only to splash the water to cause a blaze of light to follow. A French naturalist placed on record the fact that so brilliant was the light occasioned by this minute organism in African waters that he read by their light standing on a beach where a heavy surf came pounding in upon the sand. The light of this little creature is remarkable not only for its vividness but for its many different tints. Now it is a fitful vivid green, again the water is a blaze of yellow light, or orange. At such times, when a ship is plowing along, the light is so brilliant that the sails and rigging are brilliantly illumined, casting weird shadows.

Some Noctilucæ emit a clear blue light, but when the same animal is disturbed it appears white with green and blue flashes of great beauty and intensity—a telling illustration of the boundless, and marvelous, resources of nature. Many interesting experiments have been tried with these dainty light givers. A tube fifteen millimeters in diameter was filled with them, and by shaking this novel lamp a printed page was read a foot distant; yet when a delicate thermometer was thrust into the fiery mass, the mercury was not affected in the slightest, showing that here was that wonder of wonders—vivid light without heat—a secret which man has vainly endeavored to wrest from nature. The vast number of these minute creatures can be realized when it is said that the ship Magenta sailed nearly five hundred miles among swarms of Noctilucæ, which gave splendid displays of phosphorescent light at night. Sometimes the light emitted was milky white; again it was green, or blue, the different species possessing different colors.

II. THE SPONGES

Fig. 13.—Living sponges.

Almost every day, for several years, I devoted one or more hours to the pastime of floating or drifting over a part of the great coral reef which constitutes the most westward portion of Florida where it reaches out in the direction of Yucatan. The islands composing the group are the Tortugas Keys, and are just above water; indeed some disappeared when a particularly heavy hurricane came, and in the center of the island upon which I lived, the water at very high tide appeared above the surface.

Among the commonest objects seen on the reef were huge vases (Fig. 13). They were found in water from a foot to fifteen feet or more in depth, and were attached so strongly to the bottom that it required considerable strength to lift them up. Some were three feet high, and I have often dived down to them and for a few seconds sat upon them as a jest for the edification of my companions in the boat above. A common name for them on the reef was "Neptune's Seats." The seats were sponges, and their collection on the Florida reef has for many years constituted an important industry, vessels being fitted out from Key West and other places for this purpose. This industry is also followed in the Mediterranean Sea, where the finest sponges known are found. To take them, men go out in small boats, and in shallow water bring them up with hooks. In the greater depths a water box is used, a box with a glass bottom, which placed over the water makes everything visible, and by this the sponger secures the sponge. Other collectors, especially those of Syria, dive for them and wrench them from the bottom, then ascend to the surface with the load. There are many different kinds of sponges, those commonly used being divided into grades, from the delicate face sponge to the coarse specimens used for washing carriages. Then there are hundreds of kinds of sponges which have no value but to form veritable mimic forest growths at the bottom of the sea (Fig. 14). Some grow upon stones or sea mud and are brilliantly colored; others again are like glass, and all represent one of the lowest forms of animal life, yet one of the most beautiful, and one that is very useful.

Fig. 14.—A sponge (Ascetta primordialis): I. o, exhalent opening; p, inhalent pores; g, ova. Starlike spicules are seen on the outside. II. Section showing pores (p), with cilia of the cells extending into them. III. Cell showing lash, or cilium. IV. Same, with lash retracted. V. Embryo of Ascetta mirabilis. VI. Section of embryo.

In handling a sponge the most indifferent person has not failed to observe two peculiarities, one that the sponge is soft, another that it is filled with holes, small and large, and has a marvelous faculty of retaining water, in which property lies its value to man. Now if we take a sponge and cut down through it, making a section, we shall find that these holes are nothing more or less than doors or mouths which lead into the interior of the sponge. If we are so fortunate as to have a live sponge to study, we shall see that water is being forced through all the small pores and out into the larger ones; and if we could examine the water, we should see that the water which passed in, is laden with living creatures which have been described in a previous chapter, while the water which is discharged contains little or no living matter. The reader will have suspected what this in-going and out-coming is. It is the operation of eating on the part of the sponge, which, while it looks very much like a plant and appears to be growing from the ground, is an animal, or a community of many cells—a many-celled animal.

Fig. 15.—Flint spicules highly magnified.

In our section of a sponge we may follow the winding channels which connect one part of the sponge with the other, and we see that the body is a mass of fibers made up of curious and beautifully shaped objects called spicules (Fig. 15). The spicules are the bones of sponges, the hard portion, the framework. In the sponge we find here and there little oval rooms, and in these are packed, side by side, minute objects with tails (Fig. 16). Each little cell has its tail upon the outside, which is really a whip or lash, used for capturing passing food. In these rooms the cells congregate and are fed by the constant onward flow of water laden with food. The food is in the shape of minute animals and plants which these little whips catch as they pass by. The whips have another purpose; their constant motion serves to force the water along through the canals, carrying air as well as food.

Fig. 16.—Parts of a sponge (Grantia): B, cross section showing pores leading into tubes C´; C, enlarged tube; D, cells magnified.

Some of the sponges have very singular shapes. One is called the finger sponge, and often takes the form of a hand. Others are very long and slender (Fig. 17). Some are perfectly round; others creep over stones and form a brilliant red matting, a charming object in the water.

The great vase or seat sponges are often the habitations of animals of various kinds—shrimps, crabs, and fishes. After a hurricane I have found a windrow of them on the beaches. When the sponge is taken from the water it is fleshy and seems covered with a reddish colored mass of jelly, or it is black, brown, or yellow, as the case may be. The sponge of commerce is the skeleton, the mass of living spicules after all the animal matter has been removed and the framework, elastic and soft, thoroughly bleached.

Fig. 17.—Sponges: A, Axinella; B, Sycandra.

The variety in shape, color, and size in sponges is remarkable and can not be appreciated until a collection of these lowly animals is seen with the individuals side by side. In such a collection one sponge, shown in Figure 18, will attract the observer for its remarkable beauty; indeed few would consider it anything but a beautiful glass vase. Some years ago one was brought to England from the South Pacific and sold for several hundred dollars. It was believed to be the work of some skilled native artist in glass. But finally some one discovered that the natives did not make them, but hooked them up from the bottom of the ocean, when they had no resemblance to the glass vases of commerce sold for enormous sums under the title of Venus's flower basket. When first brought up the vase was dark and covered with mud; then it was found that it was a sponge, and that the so-called glass was merely the interior, the framework over which was drawn the ugly exterior animal matter. It is needless to say that the enormous price of the Venus's flower basket dropped, and it can now be bought for a few cents.

Fig. 18.—Skeleton of a sponge.

No more beautiful object can be imagined than this sponge, known as the Euplectella. It has great wisps of glasslike matter at the bottom, which anchor it in the sand or mud, and the framework appears to rise upward in whirls, the surface being made up of squares or basket work, so artificial that it is difficult to believe that it is not of human make. This vase has a top to it. It is perforated with squares, and is often a prison for various small animals, as crabs, which have passed into the interior when very small and which are now too large to escape, only their claws or feelers being seen protruding through the little portholes.

The sponges in their habits show a variety of tastes. Many grow in the mud, the majority upon rocks. On the New England shores there is one of a yellowish hue which lives in the sand. It is very light, and the pores are so fine that the sand does not enter them. After a storm on Cape Cod thousands are found on the beaches, blown far inshore. Black and pure white sponges are found in fresh water as well as in salt. They increase by depositing eggs. In one stage of their development the young (Fig. 14, V.) are free-swimming animals.

III. THE JELLYFISHES

Fig. 19.—A jellyfish (Pelagia).

Among the most beautiful and fragile of all animals are the singular forms which we call jellyfishes (Fig. 19). They are so delicate that we can not lift them, and in many instances they have ninety-five per cent of water in their composition. They would almost seem to be purely ornamental did we not know that they fill an important niche in the hall of nature, constituting almost the sole food of many whales.

The jellyfishes are found in all waters, salt and even fresh. They may be seen floating near or at the surface, often in vast numbers. Sometimes they are found deep in the heart of the upper part of the ocean, often in such quantities that the water appears to be filled with their graceful shapes.

In the Santa Catalina Channel a beautiful lavender-hued form is common, the water being alive with them at times, and I have seen specimens with tentacles streaming behind them an estimated length of twenty feet, the entire animal appearing like a huge comet in the blue sky of the ocean. Mrs. Agassiz describes a jellyfish called Cyanea which was six feet across its disk and which had tentacles over one hundred feet in length. Specimens have been seen in East Indian waters which were much larger, having an estimated weight of several tons. An English naturalist describes one which stranded in India and gave out so vivid a light at night that the natives were afraid to approach it; yet large as was this monster, a few hours in the sun caused it to disappear or literally evaporate, water forming so large a part of its make-up.

In appearance the jellies resemble umbrellas, dinner plates, or inverted bowls, from which depend streamers or tentacles of various kinds and shapes, often richly colored, especially the very minute forms. The mouth is in the center, the eyes are around the edge of the disk, while the huge tentacles, which can be lifted or lowered as fancy dictates, are so many fishing lines by which this jelly finds its food. I have often watched them floating near the surface, the delicate vermilion-tinted tentacles floating gracefully about, and serving as so many tempting baits. Should a sardine or other small fish venture to attack this tempting lure, we can almost imagine it struck by an electric shock, as it rolls over dead. The secret is very easily discovered. Lift the tentacles with the hand and a burning sensation will be experienced, in some cases very painful. The tentacles of the jellyfish are armed with stings.

Fig. 20.—Lassos or weapons of a jellyfish.

The weapons are known as lassos (Fig. 20). Under the microscope the tentacles appear to be filled with little cells or oblong objects, which when examined are found to be capsules (C) resembling long glasslike bodies in which is coiled a thread. This latter is a miniature javelin, and when the tentacle of a jellyfish is seized by a fish or an enemy, tens of thousands of these cells literally explode (D) and the javelin springs out like a Jack-in-the-box (A) and penetrates the intruder. With many jellyfishes the effect of this bombardment is a stinging sensation. It paralyzes small fishes which, when benumbed, are lifted up by the tentacles and eaten.

Fig. 21.—Jellyfish and young (Aurelia).

The jellies develop in various ways. In Figure 21 we see a common and very beautiful form resting on the rocks. Near by are various little plantlike creatures, the young jellies, which undergo a remarkable series of changes in their growth from the egg to the adult form. Minute eggs are deposited in the autumn, which drop into the crevices of the rocks and soon change to pear-shaped objects which attach themselves to the bottom. Each little jelly pear (Fig. 22) divides after a while until it looks like a pile of platters one upon the other. The upper one dies, and the rest break away, each becoming a separate jellyfish, which ultimately grows to be a giant.

Fig. 22.—The development of a jellyfish.

The story of the growth and development of these little jellies is one of the most marvelous pages in the history of nature. In some forms the father and son are entirely different, and it is only the father and grandson that resemble each other. Not only this, the father is a seeming plant, while the son is a free-swimming jellyfish of great beauty. The seeming plant is in reality a hydroid community. The buds are immature jellyfishes which finally break away and assume the typical jellylike form, free swimmers bearing not the slightest resemblance to the parent. This jelly deposits eggs which attach themselves to the bottom and become not jellies but the shrublike form. Hence it is the parent and its grandchildren that bear a close resemblance to one another.

Fig. 23.—A large jellyfish (Cyanea).

Fig. 24.—Flowerlike jellyfish (Lucernaria).

No conception of the beauties of the jellyfish can be formed from pictures, or from the stranded "sunfishes" found along the shore at low tide. In the water they move along or swim by the slow pumping or rising and falling of the umbrella or disk, and are of all the colors of the rainbow. Some, like the dark, lavender-splashed specimens, can be seen from a long distance, while others are almost invisible, in fact, are like glass or crystal, and interpose no obstacle to other forms beyond. The ocean is filled with them; their chaste shapes presenting one of the most beautiful spectacles to be observed in the ocean as they drift about. Some are merely great disks towing behind them enormous masses of pink fluted jelly, as in Figure 23; others are simple flowerlike forms (Fig. 24).

If these graceful forms are beautiful during the day, what shall we say of them at night, when they blaze and glow with marvelous phosphorescent lights of yellow, green, and gold. Gazing into the ocean these great jellies appear like comets moving through the clear atmosphere of the sea. The Cyanea is pale blue. One jelly, called Melicerta, emits a pale golden radiance, and Rhizostoma (Fig. 25) gives out a fixed steely blue light. It would be difficult to find one out of all this marvelous procession of living gems that does not emit a light more or less peculiarly its own.

Fig. 25.—Jellyfish (Rhizostoma).

If this phosphorescence is fascinating as we are drifting over the scene and the light givers are not alarmed, how much more dazzling is the display when the sea is beaten into foam. In a certain cave on the coast of Santa Catalina Island, California, the sea rushes in and, striking the rocks, rises like a wave of fire and bathes the entire interior with liquid light which slowly falls in gleaming rivulets to the sea.

But the most magnificent display is seen at Point Firmin Light during a storm. Here stands a lofty rock pillar which has breasted the sea for ages. At low tide, when a storm sea strikes the ledge, the spray rises to an altitude of three hundred feet, and spreading as it rises, fairly fills the air with a gigantic mass of silvery light, that on a dark night presents an appalling spectacle as it drops, changing its shape continually. On such nights the line of breakers changes into silvery flame, while the roar resembles a cannonade, fairly shaking the earth. In the breakers the jelly light givers are breaking up and adding fuel to the seeming flame. Some, as Pelagia, are luminous over their entire surface; in others, the light is confined to certain parts, which are either fixed or flashing lights. How vivid this light is may be imagined when it is said that a single jellyfish, Aurelia, when squeezed into a glass of milk, has produced a light by which a letter was read.

This peculiar phosphorescence is not their only interesting feature. Nearly all the jellies afford protection to fishes, crabs, and various small animals. As I drifted over the waters of the Gulf of Mexico almost every large jelly that I examined had one or more little fishes of the mackerel family up among its lobes or tentacles. As they always resembled the tentacles in tint or color, a delicate pink, they found protection amid the death-dealing darts. The most remarkable example of this strange companionship of dangerous jellies and delicate fishes is found in the Physalia, or Portuguese man-of-war (Fig. 26), one of the most beautiful of all the animals that make up the group to which the jellyfishes belong. Physalia is a bubble tinted with purple hues, four or five inches long—a fairy ship of pearly tints. On its upper portion is a sail which can be raised and lowered, while from the lower part depends a mass of beautiful blue or purple tentacles which sometimes are nearly one hundred feet in length. During the summer of 1902 I found them on the outer islands of the Texan coast in great numbers, stranded on the sands, while scores of others sailed on through the pass into the quiet waters of Aransas Bay. Among the islands of the Tortugas group I often saw them dotting the calm waters, the sunlight on their delicate tints presenting beautiful combinations of colors.

Fig. 26.—The Physalia.

It may appear strange that one of the most resplendent of animals should be the most dangerous, yet such is the case. The attractive tentacles which drag behind the Physalia are deadly to almost every fish. I have found a hawkbill turtle weighing twenty pounds caught and benumbed by one; and fishes which touch the seeming worms roll over dead, as though stunned by an electric shock. In swimming around one of the keys of the reef I unwittingly passed over the train of one, and if I had been alone, I doubt if I could have reached the shore, so terrible was the burning pain. A year afterward my flesh had the appearance of having been tattooed in fanciful designs. Yet despite the deadly nature of this maze of traps and lures, a little fish lives up among them, and what is more remarkable, is the exact color of the tentacles, a rich blue. So exact is this resemblance that it is very difficult to see the little attendants, but if you lift the dainty man-of-war by its sail, they rush about greatly alarmed by their exposed condition. I have been told that the Physalia eats these attendant courtiers, but in hundreds of specimens which I examined I never saw the little fish in the toils. They swam about among the death-dealing tentacles with the greatest freedom. The secret of the poison lies in the lasso cells of the tentacles, as in the case of the jellyfish, but in this instance they are much more poisonous. Along the southern beaches, where the Physalia is common, their stranded hulks form after storms a windrow of mimic balloons which explode like torpedoes beneath the feet, as one strolls along the sands.

No branch of the animal kingdom contains more beautiful and radiant forms than that which includes the Portuguese man-of-war. They are the fairy crafts of the sea, graceful, seemingly formed of water in some instances, and nearly all so delicate that they usually drop to pieces when captured. I have kept all for a brief time in confinement, but few survived more than a few hours.

Fig. 27.—Velella.

Fig. 28.—A, Praya; n´n´, mouths; ss, swimming bells. B, single polypite (p), enlarged.

In a tank at Santa Catalina Island I had at one time, besides a Portuguese man-of-war, the delicate Velella, a raft of sheeny silver which floated on the surface, having a silvery sail (Fig. 27), beneath which hung short tentacles of a brilliant hue. More beautiful than these were the "swimming bells"—strings of beautiful pink and crystal bells attached to a central cord (Fig. 28). One of these, Praya, three or four feet long, was a veritable string of little pumps, each of which pumped water very rapidly, urging the entire animal along. Each little cup seemed carved in glass and colored by some artist, so perfect were the tints, so delicate was the design. Many of these forms could be seen in the ocean only by fitful glances, so delicate were they. Most beautiful of all these prisoners in the tank was one called Physophora, or by the Italian fishermen, Boguetti. It had a central stem like the glass of a thermometer, the bulb being uppermost and filled with a gas that was almost exact in its resemblance to mercury. When the bulb was full the animal floated at the surface. I have watched the animal force the gas down by repeated restrictions of the tube until it could descend beneath the surface with ease. On the sides of the central pillar were numbers of beautifully tinted pumps, the locomotive organs. Underneath was a mass of lacelike tentacles, richly tinted, purple and vermilion, so Physophora was one of the most gorgeous objects to be imagined. A unique feature of this animal was its rapid movements. When it so desired it dashed around the tank with great velocity, in strange contrast to the labored movements of other jellylike forms, or the utter and complete helplessness of Physalia, Velella, or Porpita. These latter were ships at the mercy of every breeze, the Physalia alone being able to anchor itself on a lea shore, but always beaten in by the heavy surf.

IV. THE SEA ANEMONES

In the last century many of the animals of the ocean were considered plants, and the sea anemones, which appear to open and shut like flowers, were described and painted in verse and prose as the flowers in the gardens of the sea. The sea anemone, common in almost every rocky pool, and found everywhere from the rocks bare at low tide to the greater depths, certainly has a very flowerlike appearance, some of them resembling a flower without a stem. Petals branch out on every side. Some are large, some small, and as though to carry out the idea the anemones are of all possible shapes and colors. Some are vivid red, others blue, some almost white, others spotted black and white, brown and barred. Almost every color is seen. Some are tall and slender, five or six inches high; others are flat. Some live in exposed places, as the luminous form attached to the shell of a hermit crab in Figure 29. Others bury themselves in the sand or hide beneath large jellyfishes, displaying the most remarkable tastes and fancies. Little wonder that the ancients believed that they were flowers. But touch one, and presto! it appears to draw within itself, and becomes a mere mound in place of the gorgeous creature which spread its splendors to the current.

The sea anemone is a highly organized animal several degrees above the jellyfishes in the scale of life, yet a very humble creature after all. They are tubular in shape, and are attached to the rocks by a sucking disk which clings so tightly that it is only with great difficulty they are forced off. Yet they have the power of moving, and slowly, very slowly, drag themselves along. Some move perhaps three or four inches a day; but this would be a long journey for many anemones, and the greatest number are fixed for life and live in crevices in the rocks. The only one I ever saw actually moving was traveling slowly across the glass of a tank. As it moved small pieces of the disk appeared to be torn off and left behind, each of which grew into a perfect sea anemone.

Fig. 29.—Sea anemones—one in the upper right hand corner is a luminous form on a hermit crab.

On the upper portion around the rim are the tentacles, armed with the same kind of ammunition (Fig. 30) found in the jellyfish, namely, lassos. In the center is the mouth.

Fig. 30.—Lasso or dart of a sea anemone.

We may imagine the anemone feeding, and we may easily see what occurs. The anemone displays its beautiful flowerlike face; it is spread out, waiting for prey. A shrimp comes swimming along, and innocently drops upon the beautiful flower. The moment it touches the attractive arms it is pierced by the lassos, and unless very vigorous is soon involved. The arms are thrown over it, the body shrinks, grows perceptibly smaller, the shrimp is pressed against the mouth, and finally ingulfed, and the once gorgeous anemone resembles (Fig. 31) a mere mound, a form which it may retain until the food is digested.

Fig. 31.—A sea anemone closed.

The structure of this interesting animal may be observed by glancing at Figure 32. The stomach is placed in the center of the animal, and is held in position by a number of partitions that are attached to the side of the anemone. These form little rooms in the body of the anemone, arranged about the stomach, but not opening into it. Each room has two windows leading into the room beyond, hence all are connected, and at the bottom all are connected with the stomach. Each room connects upward with a tentacle, which is hollow. When the animal is swallowing, the food passes down and is floated in water through the various rooms, the hard portions being rejected at the mouth. The animal has a current of water circulating through it almost continually, and it is water which, filling them, makes the tentacles stand upright and firm. Between the bases of the tentacles are the eyes. When the animal closes up, it forces the water out of its mouth and is able to shrink to a small and inconspicuous object.

Fig. 32.—Section of an anemone: c, tentacles; g, little rooms; d, mouth; g´, opening between rooms; a, sucking deck or foot; e, stomach.

Lowly as are the sea anemones, they often display an amount of intelligence that few would give them credit for. On the Florida Reef was a large lagoon, its bottom pure sand, and so light that the slightest dark object was easily observed. In the sand, buried several inches deep, lived a large anemone, whose normal hue was a dark brown, but when expanded was almost the exact color of the sand; not only this, its tentacles were covered with bits of sand. In a word, the anemone had disguised itself so that large and threatening fishes would not see it, as they swam along in search of food. The habit of placing bits of shells and sand on the tentacles is a common one. I have noticed it in a sand-living form on the California coast. As the tide went out and left the anemones dry, they were invariably covered with sand which adhered to the tentacles as though it had been gummed. To accomplish this protection from the hot rays of the sun, the anemone had picked up the atoms of sand with its tentacles and distributed them over its surface. As there were thousands of pieces, the amount of work may be imagined.

Anemones are found in many strange places. One, as we have seen, rides about upon the back of a hermit crab; another is so often found on the top of an ordinary crab that it is evidently a habit of the anemone. The anemone thus travels about with its host and shares its food. In the Indian Ocean a German naturalist found on every crab of a certain kind, which he caught, a sea anemone fastened upon the inside of the large biting claw. Thinking it accidental, he caught a number of crabs, but nearly all had the small anemone, which was so placed that when the crab raised its claw to its mouth to eat and tear its food, the sea anemone was in a position to obtain a full share of the food. Still thinking that this must be an accident, the naturalist placed a large number of the crabs bearing the sea anemones in a tank and removed the anemones with a knife, placing them in the water. The following day when they were examined every crab had its attendant again upon its claw. Again the experiment was tried, and again the crabs collected their curious attendants. The naturalist now cut one of the animals into several pieces, and even then the crabs attempted to collect them.

The anemones deposit eggs in vast numbers, which change into strange, free-swimming animals that finally settle upon the bottom and soon grow into the adult forms. They have another method of developing. Singular little "buds" appear on the sides and base of the adult, which soon resemble the parent. The anemone is very long-lived; specimens have been kept for nearly a century. They also have a marvelous faculty for renewing themselves if injured. If one is divided, sometimes two anemones will be the result, recalling their distant cousin the little hydra, which when turned inside out receives its food and eats as though nothing had happened. No amount of mutilating appears to affect its various portions, as each soon develops into a perfect hydra.

The sea anemone is a common form of the aquarium. It is easily secured by those living near the ocean, forming a most interesting pet, taking food from the hand, and soon proving itself possessed of a remarkable appetite. The anemones are among the great purifiers of the ocean, devouring a vast amount of dead matter which might pollute the water, and continually pumping the water through their systems, sifting out the animal life, dead or alive. Aside from this, the anemones are chiefly useful as beautifiers of the ocean. In the Mediterranean Sea they are sometimes eaten by the Italians and French. Certain fishes and crustaceans prey upon them.

V. THE CORALS

The real gardens of the sea, the "Gulfs enchanted where the siren sings and coral reefs lie bare," are in the tropics, where the great coral reefs extend for miles in countless shapes, forming branches, heads, fans, and many forms which never fail to delight the eye of the observer. For many years I lived upon a coral key or island in the center of a coral reef. The key was half a mile in circuit, and was made up of coral sand, or sand composed of ground coral and shells. It was just above the surface, so near that almost anywhere salt water could be found a few feet below; yet in this sandy soil cocoanuts, bananas, and other tropical plants grew in profusion. A grove of bay cedars and mangroves added to its attractiveness and gave it the name of Garden Key.

Fig. 33.—Branch coral (reef builder), showing polyps expanded and withdrawn.

The history of this reef is easily told. Ages ago there was no reef. There was no island, but perhaps a submarine plateau, a long distance below the surface. It gradually grew by the dropping of the minute shells described on page 15. After many ages it attained an altitude which brought its summit within one hundred or two hundred feet of the surface. Now its growth became more rapid as a new factor came upon the scene. The reef-building corals do not, as a rule, thrive or grow in water deeper than two hundred feet, and nearly all prefer water very much shallower. So, as soon as the submarine hill entered this zone, the eggs and young of the various reef-building corals (Figs. 33, 37) obtained a foothold, and the growth was ever upward, countless forms aiding in it. The lower portion was continually dying, the animals occupying only the upper story, so that a cap of stone was being formed on the top of the hill which after many years reached the surface. The sea now broke up the tips of the branch coral. They became ground up. A curious seaweed which secreted lime appeared, and this and the ground coral and shells formed a muddy flat which, aided by various objects that float upon the ocean, constituted a miniature island. Now something which resembled a cigar, one end downward, came floating along. If we could have examined it, curious little rootlets would have been seen growing from the lower portion. This stranded on the island, and the little cigar proved to be the seed of the mangrove tree; its roots grew and caught in the mud, and soon a tree appeared growing on the new-born island. Its roots presented a base, about which sand and mud rapidly accumulated, and so the key or island grew until it became the Garden Key of to-day.

Fig. 34.—Mushroom coral; a single polyp (Ctenactis), one fourth natural size.

Such is the history of an ordinary coral island, built up, not by corals alone, but by countless animals. Even to-day some writers describe this coral animal as an "insect," but it is an entirely different animal, being a polyp, so closely related to the anemones that very few can distinguish between them. For the purpose of examination we may consider a coral animal as a sea anemone possessing the faculty of taking lime from the sea water and secreting it in the little rooms which we have found existing in the anemones (Fig. 32), there forming a little platform, then partitions or cells, as the case may be. In Figure 33 is shown a section of branch coral. The starlike spots are the polyps with their tentacles outspread as in feeding. They may be considered so many anemones, each resting in a little cell, and all connected by a common brown or olive-hued tissue. This is a many-celled coral, while that shown in Figure 34 is an example of a single-celled coral, a huge anemone with a framework of lime. These single-celled corals are often found in very deep water.

Fig. 35.—A single polyp coral (Caryophyllia).

In the vicinity of Garden Key on the Florida Reef there are six or seven keys, each almost surrounded by a deep-blue channel. On the east a long fringing reef is forming which some day may form an atoll (Fig. 36). In this lagoon are acres of beautiful branch coral, rising two or three feet from the bottom in a mass of points almost bare at low tide, and at the very lowest tides becoming exposed and dying. At certain places on the edges of channels are vast heads of coral (Fig. 37), some being four feet high and six or seven feet across. Many of these are hollowed out into great vases and filled with beautiful sea fans, the Gorgonias, in yellow, lavender, and brown, while in and out swim fishes of beautiful colors. The surface of these heads is often dotted with objects which resemble flowers of gorgeous hues, red, blue, white, and spotted. At the slightest alarm or jar these disappear, showing themselves merely worms, which have bored into the coral, the flowerlike petals being the breathing organs. Along the sides of the channels the groves of branch coral (Fig. 33) dip down, and thirty feet below the surface the growth is much more vigorous, the branches often being three or even four feet in length, and resembling the antlers of the elk.

Fig. 36.—An atoll.

Wishing to see how deep the coral descended, I had a boat held on the edge of the channel, and taking a heavy stone in my hands allowed myself to sink. The stone carried me down rapidly for perhaps twenty feet, until the water was perceptibly colder and the light very dim, yet as far below me as I could see, the almost perpendicular wall of coral extended, being in all probability sixty feet in height and almost vertical. As I swam upward not four feet from the jagged points, I could plainly see the beautiful coral with parrot fishes garbed in brilliant tints, poising among the great branches.

The coral on this reef grows or flourishes more or less in communities. The great heads are found in groups, the branch coral in plantations, if the word can be used, in the center of the lagoon and on the edge of the deep channels. On a shallow point, growing among seaweeds, I found small heads five or six inches long.

Fig. 37.—Coral head, with many polyps (Astræa).

In the surf, where it piled in upon the reef, grew a beautiful form known as leaf coral, spreading out like the horns of the moose in great leaflike shapes. This crept near the ground, and was surrounded by its cousins, the Gorgonias, in lavender and yellow. The whole presented a beautiful appearance when seen from above through a water glass or glass-bottomed boat.

In most of these corals the branches were covered with the small cells of the coral animal, made up of thousands of individual polyps. Others again had very minute cells, yet the entire head might weigh a thousand pounds. Another large head is called brain coral, as the animals are arranged in deep trenches or convolutions. In the star coral (Astræa, Fig. 37) the polyps resemble stars and are much larger than those on other corals.

Occasionally I have found a branch of coral on which there was, perhaps, a bunch of eight cells, each half an inch across, the group resembling a bunch of flowers. These were generally in the deeper parts of the lagoon, where the water was fifteen or more feet deep, and therefore out of reach of the coral tongs. I would, therefore, dive down for it, the coral being distinctly visible in these clear and limpid waters. This rose coral, as we called it, was the work of a few polyps. Another kind was very delicate, the polyps being almost invisible. It was called pepper coral, as when tasted it burned the tongue violently. Still another, which grew in heads a foot or two across, had a peculiar habit of floating when free of animal matter. Large heads, when tossed from the beach where they had drifted, went sailing away like boats.

Still another coral has cells at short intervals up the branch; another is cup-shaped with a single polyp. One of the most remarkable corals (Fig. 38) has the cells of the polyps arranged after the fashion of a pipe organ, from which the coral takes its name, while the polyp itself, when expanded, resembles a daisy. Formerly corals were supposed to be confined to the warm waters of the tropics, but this is true only of the reef builders, which require a temperature not lower than 63°, and are rarely, if ever, found at a greater depth than about 180 feet. Single polyp corals, like Fungia, are found at great depths in the ocean, and certain corals grow in the Santa Catalina Channel on the Pacific coast. In the Atlantic, as far north as Long Island Sound, where the water is often icy cold, is found the beautiful Astrangia, a coral in which the polyps are pure white and about five one-hundredths of an inch in length.

Fig. 38.—Organ-pipe coral (Tubipora): A, cell tubes; B, polyp expanded.

In a general way we have passed in review some of the typical corals, and may now glance at their manner of growth. If we cut one of the cells of a coral across, we shall have a figure similar to that shown in Figure 39. The white radiating partitions are coral, the black spaces are rooms, which correspond to the little apartments in the anemone. The coral develops by eggs and by budding, just as in the case of its cousin, the anemone. The eggs, after enjoying a free-swimming life for a while, settle upon the bottom and begin to secrete lime. They do not build up a house as the mythical "coral insect" is described as doing, but secrete it much as any animal secretes its bones or shell. As the water flows through the animal it is enabled to secrete the lime dissolved in the water. If we could watch every step of the growing process, we should first see a little platform of lime attached to the stone or object upon which the young coral animal has dropped, then a little edge or rim which increases in size daily. Out from this rim shoot the partitions, as shown in Figure 39. It will be observed that they do not meet and join, but leave a place in the center for the stomach. Finally, the cell is completely formed, and we have a perfect cup of lime, a coral cell in which is ensconced the anemonelike coral polyp. Its color is an olive brown, and when the polyp is expanded its little tentacles resemble the petals of a flower. With these it catches food, which it eats in very much the same way as do the anemones. If this cup is a branch coral, soon a bud appears upon the side, and a new cup or cell takes shape. Then another is added, and we see the coral enlarging, branching out either by budding or simply dividing until a large branch is the result.

Fig. 39.—Sections of a coral cell.

This growth is much more rapid than is generally supposed. The brain coral has been known to grow an inch or double its size in a year, and branch corals grow six or eight inches in this time. The corals and reefs form the great girders of the globe. The one off Australia is over a thousand miles in length, and all over the world are found fossil reefs. Thus in the Helderberg Mountains of New York I have followed and traced a coral reef, quite as wonderful in its way as that now growing and reaching out in Florida. By some upheaving of the earth's surface it has been pushed up into the air, a monument telling of the wonderful changes in nature and of the time when the waters of New York were as warm as those of Florida.

Fig. 40.—Surface of sea fan, enlarged.

Side by side with the corals and among the most beautiful objects of these submarine gardens, we find objects which resemble plumes and fans (Fig. 41). These are called Gorgonias, and are cousins of the corals. They resemble fans made up of a fine network or reticulated surface (Fig. 40). They are richly colored yellow, brown, and lavender, those of the latter color being particularly beautiful. When there is a surf they can be seen waving and bending gracefully, like the limbs of a tree in a gale. One of the best known of this group is the red coral of commerce, found in the Mediterranean Sea and the Indian Ocean. When alive, the coral base or branch is covered with a crust or skin in which the animals live, connected one with another. The polyp stands very high and is white. The crust itself, the solid lime base, is formed of a number of minute parallel tubes. This coral is dredged by collectors in the deep water and is scraped and polished until the beautiful red color, so highly prized for jewelry, is brought out.

Fig. 41.—Sea fan (Gorgonia).

Fig. 42.—Sea pen.

Closely allied to the corals are the sea pens (Fig. 42) which are common in almost all waters, and among the most beautiful forms. They are communities of polyps. In the sea pen the polyps are arranged along the branches so that a fluffy fan or an ostrich plume is imitated. I have taken these animals from deep water when they measured perhaps five inches in length; but an hour later when placed in a tank the insignificant animal had expanded until it was five times as large, and beautiful beyond description in its garb of delicate pink. At night it was a blaze of light which flashed from branch to branch, from polyp to polyp. When irritated in a perfectly dark room this specimen created so brilliant a phosphorescent light that I could almost read large print by it.

Fig. 43.—Veretillum, a wonderful light giver.

In the deep sea lives a giant form, the Umbellularia, four or five feet high; and there are many more, all of which add to the lights of the deep sea. Near allies of these attractive forms are the comb bearers, free-swimming, jellylike forms of great beauty and grace. I have kept the radiant Pleurobrachia in a tank where I observed its wonders and beauties. The one known as Veretillum (Fig. 43) is very beautiful and a marvelous light giver.

VI. THE STONE LILIES

A number of years ago I took a number of walking trips over that section of New York state known as the Catskill Mountain region. The start was made at the mouth of Catskill Creek, which was followed up into the mountains until we came to a peculiar light, slate-colored rock. This rock, where the stream had washed the earth away, was dotted with little disks (Fig. 44), which being harder than the rock itself had been weathering, and stood out in high relief. A mile or two from the river the rocks were covered with these disks, in fact, seemed to be made up of them. Some were large, some small, as if millions of pipestems had been cut into sections and scattered about.

Fig. 44.—Sections of fossil crinoid stems, Catskill Creek.

These disks told an interesting story. We read by them that ages ago the region now covered by farms and summer resorts was the bottom of a shallow, tropical sea. We could go further and describe even the appearance of the bottom of that sea, and what grew and lived there. Scattered about on the rock were myriads of shells, corals, teeth, fish bones, and a variety of objects, all the remains of animals which once lived in this ancient ocean.

We find that the little disks fit together, and collecting them, pile them up, forming a stem a foot or more long. Among them we find one which is attached to a rootlike object, and this is placed at the bottom. Near by we find a flowerlike or budlike form (Fig 45), which may well serve as the flower of this stem, and so we add it and produce a striking resemblance to the crinoid shown in Figure 46. This is an interesting and beautiful animal which was one of the commonest forms of the ancient seas. It grew in groves and masses, as we may see by the vast numbers strewn in the old ocean bed; and when they died, they were scattered here and there and hardened into the old bed.

Fig. 45.—Fossil crinoid.

Fig. 46.—A living crinoid (Pentacrinus).

The crinoids resemble lilies so closely that they are called stone lilies. They are animals, however, related to the starfishes. They have a long stem, with rootlike branches to support it, and are capped with what appears like an inverted starfish, and is literally a starfish perched upon a stem. Fossil crinoids have long been known, and beautiful specimens may be seen in all our museums, but the fact that they still live upon the globe is a modern discovery. It is said that Agassiz stated that he expected to find them alive off the coast of Cuba, and when a deep locality was dredged, up came the living crinoids, or forms almost identical with them. Since then they have been dredged in great numbers by all the great deep-sea explorers. Some have long stems, some short. On one, the Comatula, when it is full grown, the crinoid leaves its stalk, and lives a free, roving life after the fashion of many starfishes.

The crinoid, with its long slender stem, its branching tendrils, its flowerlike top, is one of the most graceful of all animals, as might be imagined from the drawing. Examine the crinoid as closely as one may, it still resembles a stone lily, and only its slow movements, contracting and folding, suggest life. Nevertheless, it is a very complicated animal. It consists of a central body, protected by numerous plates, as seen in Figure 46. From the edges extend five, or often more, branches or arms, and from them in turn branch other arms, so that the top resembles a feather or brush, from which they are called feather stars. In the center of the stars is a mouth, food being caught by the many branching tentacles. The history of the development of crinoids is very interesting. They pass through several curious stages in the course of growth from infancy to old age, and some of the shapes are so curious that no one, not familiar with them, would suspect that here was a growing crinoid.

VII. THE STARS OF THE SEA

Fig. 47.—Basket starfish.

Fig. 48.—Lower surface of starfish (Goniaster), showing suckerlike feet; a slow mover.

Beneath almost every rock along the New England coast, and under the branch coral in the tropics, we may find a typical star-shaped animal, and by dredging offshore, thousands are brought up, even from very deep water, showing that the stars of the sea are almost as plentiful as they appear in the sky above. These starfishes are of all shapes, kinds, and colors. Some are a foot or more across, huge, domed fellows with rough backs, showing little if any signs of life (Fig. 48); others have five long legs and a small body (Fig. 49). Others, again, are perfectly round and have many rays, while some have few rays which are round, like the body of a snake, and which they whip and slash about, displaying great activity. Once in reaching beneath a coral branch to find a certain shell which I knew lived there, my hand grasped something which felt like a ball of snakes, each of which closed about it, producing a most disagreeable sensation. I drew it out and found it was one of the starfishes, common on many shores as the basket starfish (Fig. 47). As I lifted it up it was a veritable mass of coiling arms, a Medusa's head of the sea, coiling and uncoiling. It was merely a starfish in which each arm branches in two parts, each branching out into two again with the result pictured, a confused mass of arms. As I lifted my capture above water and it felt the air it began to shed its arms, so that it fairly rained pieces of starfish, and before I reached the boat, but a few feet away, all that remained was the body. My starfish had almost committed suicide.

Fig. 49.—A deep-water starfish (Ophiocoma), a rapid mover.

The starfishes are found everywhere in the tropics. Every bunch of coral contains scores of them. Many resemble spiders, and are a vivid red hue, others are bronze or brick red, while still others are barred or spotted, as in Figure 50. They are all interesting creatures, especially our common Eastern starfish, which is found in little caves at low tide, clinging to the walls. It is not very attractive in appearance, and apparently not disconcerted by being left by the tide.

Fig. 50.—A brittle starfish.

If we take a common starfish and turn it upon its back, we observe that the lower portion is covered with short tentacles, each having a little sucker on the end. These are the feet of the starfish, by which it walks or moves. In the center of the body is the mouth leading into the stomach which reaches into each ray. The eyes are at the tip of each ray. On the back of the star we find a little red disk with a rough surface. This is really a sieve for straining the water which pours in through a little canal encircling the mouth and leading off into each arm, carrying water to each one of the myriads of feet.

The feet move independently, and the starfish walks much faster than would be imagined. This can be illustrated by the sudden appearance of the starfish, in Long Island Sound. One night when the oyster men left the beds no starfishes were seen. The following day they were there in such vast quantities that it was estimated they covered the entire bed, two or three deep, and tens of thousands of dollars were lost by the destruction of the oysters.

How an oyster can be opened by a soft, helpless starfish would seem a mystery; but it is a very easy matter. The starfish drags itself over the shell and places its mouth at the end, extending its long arms downward, literally swallowing part of the shell. It is supposed to eject some secretion into the shell that causes it to open.

VIII. OCEAN HEDGEHOGS

(The Echini)

Fig. 51.—Sea urchins burrowing in the rocks.

On the Florida Reef and off the rocky shores of California one of the most conspicuous among the rock-living animals is the black, long-spined Echinus. In the water it looks like a huge pincushion (Fig. 51) filled with black pins, points outward, and every crack and crevice is filled with them. When found on the beach, despoiled of their spines, they resemble bleached shells, and are then known in Florida as sea eggs (Fig. 52). The long black spines are continually moving up and down, and constitute the armament of the sea urchin, and an effective one to all except very large fishes, as some rays, which have pavementlike teeth fitted particularly for such not especially dainty morsels. The spines emit a bluish secretion which is left in the wounds made by them, and is more or less poisonous. This common sea urchin is a type of hundreds found in almost all seas from very shallow water to the abysmal regions of the ocean.

Fig. 52.—Sea urchin without its spines.

Fig. 53.—Short-spined sea urchin, showing the biting teeth.

Some sea urchins have short spines (Fig. 53) and are almost pure white; some are flat like the sand dollars, the spines feeling like sandpaper, so short and fine are they. The latter are small, and appear to be covered with waving filaments. Many have spines like needles; in others the latter are blunt, clublike organs. Many other strange variations are seen in an exhibition of the various kinds in some museums. None are more remarkable than those having five holes through them like Chinese money (Fig. 54).

Fig. 54.—Flat sea urchin, "sand dollar."

The urchins are very closely allied to the starfishes, especially in structure. They have the same kind of feet, and among the spines is seen a singular handlike organ common to the starfishes. It has three fingers (Fig. 55) and a short stem, and is constantly in motion, its office appearing to be to clean the body. Foreign objects are taken up by this peculiar hand and passed on from one to the other until they are finally dropped off. Here is the same madreporic plate or sieve, and the structure of the Echinus (Fig. 56) is very similar to that of the starfish. The former has a long set of jaws, hence is a biter and nipper, while the starfish is a sucker. The shell of the Echinus is really a beautiful object when divested of the spines and bleached in the sun, appearing as pure white as coral after bleaching. It is made up of about six hundred hard, limy plates arranged in double rows, which contain about thirty-seven hundred pores through which the feet protrude. Despite this marvelous supply of feet, or organs of locomotion, the Echinus is a very slow walker. The spines number four thousand or more, and each one works on the ball-and-socket plan, is hollow, and moves readily in all directions.

Fig. 55.—Handlike organ of sea urchins and starfishes.

Fig. 56.—Structure of the Echinus: a, mouth; o, anus; c, stomach; f, madreporic plate; d, intestine; p, ambulacra; v, heart; z, spines.

The sea urchin is produced from eggs. The young pass through some remarkable changes before they assume the adult form. In one of these changes they appear as free-swimming animals (Fig. 57), and resemble anything but the perfectly developed Echinus. Some of the sea urchins of deep water, as the Hermiaster and others, carry their young in pouches, the spines being folded over them to hold them in place. They rarely move from the crevice on the rock which they select. They can be found in the same place for months together, and have a limited power of wearing out the rock. How the Echinus grows inclosed in so hard a shell might be a puzzle did we not know that the shell is covered with a skin, each plate being literally surrounded by it. This skin secretes lime, taking it from the water and depositing it on the edges of all the plates, so that the animal grows rapidly and symmetrically. The Echini are the scavengers of the ocean, and they aid in maintaining the clearness and purity of the water. In some countries certain kinds are eaten, and one species is valuable for its spines, which are used as slate pencils.

Fig. 57.—Young sea urchin.

IX. THE SEA CUCUMBERS

Fig. 58.—Sea cucumber, showing its breathing organs.

Once, when poling my boat over the great coral reef of the outer Florida Keys I came upon a little plot of seaweed in shallow water which was so covered with huge sea cucumbers (Fig. 58) that it would have been an easy matter to fill the boat. They were from six to twelve inches in length, two or three inches across, and bore a striking resemblance to actual cucumbers. In color they were brown, and when lifted from the water they slowly moved or twisted, sending out a stream of water. They might have been made of leather, so far as any evidence of life was concerned, and were so tough that a spear thrust into one had to be cut away, so tenacious was the hide of this singular sluglike animal. Taking a large one from the bottom, I placed it in a glass jar standing on the deck of my boat, whereupon a very singular occurrence took place. When the air began to be exhausted in the water of the glass, out from the sea cucumber came a long, slender fish, so ghostly and ethereal that when it died, as it did almost immediately, I placed it upon a piece of newspaper and read print through its body. The fish was known as Fierasfer, and it lived in the long intestine of the sea cucumber. Since then the fish has been closely studied in the Naples Aquarium, where it had the same habit, and where the attendant naturalists saw the fish come out, and return tail first.

The great sea cucumber of Florida may be taken as a type of all the group which differ mainly in size, color, and shape. Some are very short and have a decided flat lower surface; others are long, fragile, and easily broken; and many are brilliant in color. Nearly all are famous for their singular and often beautiful breathing organs which protrude from the mouth and bear the most remarkable resemblance to plants. In many specimens of the Atlantic Pentacta (Fig. 58), kept in an aquarium, this resemblance was very marked, as the animals at once buried themselves in the sand from which beautiful plants seemingly grew, being merely the breathing organs of the wily mimic. These organs vary much in size and beauty. In some species they are very elaborate, in others they are simple, flowerlike objects. The greatest variation is found in them. In one which I observed the tentacles resembled small toadstools.

Fig. 59.—Anchorlike spicules of Synapta.

Many of the sea cucumbers, or holothurians, are very sensitive, and when captured will often cast off their various organs. This does not indicate the death of the animal, as they are soon replaced. A singular trait of the long glasslike Synapta is that of cutting itself in two when starved. At first an end of the animal is dropped, then another piece, and this is continued until nothing but the mouth remains, everything having seemingly been sacrificed to save this portion. If food is now supplied, this animal will soon recover and assume its normal condition.

Synapta has no feet, their place seemingly being taken by peculiar limy spicules, shaped like anchors (Fig. 59), which are deeply buried in the skin. In its structure the sea cucumber resembles its cousins the starfishes and sea urchins, and standing on end, may be compared to an elongated sea urchin. Nothing can be more uninviting than these animals, and when dried the flesh has the consistency of leather. Yet the sea cucumber is highly regarded by the Chinese as a delicacy, and the Malays have a large fleet engaged in the business of gathering and preparing them. The animals are collected and dried, then smoked and packed in bales and sent to China. They may be found in any of the markets of these people, in San Francisco and New York. About the Pacific island of Santa Catalina they are very commonly seen through the bottom of the glass-bottomed boats, lying in the seaweed and imitating it in color.

X. THE WORMS

Few groups of animals differ so much in general appearance as the worms. Some resemble miniature snakes; others are flat, some are like needles, one lives in a cell; another stays in the tissue of some animal, while certain others infest the soil. Almost everywhere, on land and in the sea, under nearly all conditions, we shall find these remarkable creatures, which may be briefly described as animals having a head, tail, and upper and lower surfaces, and made up of a great many rings, or segments. In them we find an approach to the higher animals. Thus they have a heart, with red or green blood, breathing organs, though many breathe through the body walls, and a nervous system consisting of a minute brain in the upper portion of the small head.

Fig. 60.—Development of a planarian worm.

All the worms deposit eggs, and nearly all are remarkable for the wonderful changes through which they pass before they attain maturity. This is well illustrated in a planarian worm (Fig. 60), which seems to require the presence of another animal to enable it to complete its development. The little creature which breaks from the egg (A) is a free-swimming creature surrounded by cilia or hairlike swimming organs. By these it moves through the water, and with strange instinct searches for some animal, generally a snail, which it enters. There it becomes surrounded by a sack and produces a little creature called the nurse (b), which soon grows to resemble the tadpolelike creature (C), which is filled with small egglike or germlike objects (a). It now changes into a wormlike creature (D), in which the germs have assumed the shape of worms (a), and soon breaks forth as a little form with a tadpolelike tail (E)—a remarkable performance. But the end is not yet; another animal is necessary to complete the change. Swimming about, the little creature is swallowed by some animal in drinking, and finds its way to the liver, where it lives, the tail being lost. The animal now changes into a perfect flukeworm (F), which finally leaves the animal or host and lays eggs in the water; these pass through the same wonderful transformation. The flukeworms (Fig. 61) are disagreeable flat creatures, not often seen, the marine forms attaining large size.

Fig. 61.—A flukeworm.

Fig. 62.—Thorn-headed worm.

Fig. 63.—Supposed horsehair worm (Gordius): A, adult; B, young (larva).

Many of the worms are parasites living upon other animals. The thorn-headed worm (Fig. 62) is an example. Who has not heard the story of the living horsehair? Almost every country newspaper has told the story, that some farmer after washing his horses had found several hairs taken from the horse's tail which "were alive," and to prove the story the farmer produces the "living horsehair" which is a remarkable imitation of the long hair of a horse's tail. But the hair is a well-known worm (Fig. 63) called Gordius aquaticus. It is almost exactly like a horse's hair, two or three feet in length, and found coiled up in ponds or snugly tucked away in the interior of a beetle or grasshopper which it has seized upon as a host. The deadly Trichina spiralis belongs to this group (Fig. 64). If the vinegar bottle is examined, in what is popularly called the "mother" at the bottom, still another member of the family will be found. This is a minute round worm almost invisible to the naked eye. It is very active and disagreeable to contemplate, living in the sour, fiery liquid.

Fig. 64.—Trichina spiralis: a deadly worm from pork.

Fig. 65.—The rotifer.

In this group are many dangerous worms, as the guinea worm of remarkable length. While nearly all worms are disagreeable creatures, a few are very beautiful. Such are the rotifers or wheel animalcules (Fig. 65). These are the smallest and most active of the tribe of worms. To be found they must be sought in a drop of standing water, and as they are rarely ever over one thirty-sixth of an inch in length, a microscope is necessary. Among the throng of wonderful creatures one will be seen seemingly rolling over and over like a barrel, a minute whirling Dervish of the water. The rotifers assume a variety of shapes. One is a typical worm, another darts along by the aid of two circlets of cilia which vibrate so rapidly that the illusion of rolling is produced. No more wonderful creatures than these little worms are known, and they well repay the study required to know them well. Some of them are fixed and unable to swim, and many of the stories of spontaneous generation are due to the faculty these minute rotifers (often but three one hundredths of an inch in length) have of enduring almost any amount of drying. Thus if a pond is dried up by the sun, the rotifers seem to be able to lie dormant for a long time, and when a rain falls in the locality for the first time in years, the pool is at once peopled with rotifers which awaken from their long sleep. When it is known that Ehrenberg, the German naturalist, found that a certain species produced sixteen million young in less than two weeks, it is easy to understand how quickly a new pond might become rapidly equipped with a large population.

Fig. 66.—Polyzoans: 1, colony in plant form; 2, 3, cells of the worms magnified.

Fig. 67.—Polyzoan, magnified.

It is a singular fact that myriads of worms are seen daily, but are not known as such. These are the minute and beautiful Polyzoans (Fig. 66). They are marine animals, grow in colonies, and look like delicate seaweeds. They are often called moss animals. At the seashore we shall find the rocks and particularly the broad fronds of kelp near shore often encrusted with a delicate, beautiful tracery of pure white. In California I have found the kelp leaves at the surface covered with it, having the appearance of being coated with silver. Beneath the glass it develops into a beautiful tracery filled with cells. When magnified these cells are seen to resemble Figure 67, each one having its worm, which seems to blossom like a flower. These worms are minute imitators of corals, as they form a corallike structure, the worms having the faculty of secreting lime, as do the corals, yet they are much higher in the scale of life. One of the common seaweeds of the seashore is the sea mat or Flustra. No one would suspect it of being other than a beautiful marine plant with large leaves or branches, and many a collection of "seaweed," preserved through many years, contains the Flustra arranged among the real "plants" of the sea. But Flustra is merely a colony of worms. The minute spots seen upon it when enlarged beneath a microscope resemble so many cells of carbonate of lime secreted by the worms of the community or colony. Another species of Flustra is shown in Figure 68, and a part of the skeleton of the colony or of each cell is the peculiar bird's head which has a beak. This beak, even after the death of the worm, is seen to open and shut, snapping continually, much quicker than the little pincerlike objects we have seen in the sea urchins. The use of the so-called bird's head is not well understood.

Fig. 68.—Bird's-head Flustra: 1, Flustra mat, showing cells; 2, diagram of a single worm (Polypide); 3, bird's-head process.

Fig. 69.—Sea mat: 1, sea mat, natural size; 2, 3, section of the animal much enlarged.

Fig. 70.—Lingula.

Fig. 71.—Lamp shells, showing gills.