Chapter XXXIX: Book VII: Radiata

THE STAR-FISH. (_Asterias_, or _Uraster rubens_.)

THIS animal is often found adhering to rocks on the sea-shores. The common species is furnished with five rays, and is of a yellow or red colour. It has a slow progressive motion, and is often found on the beach among seaweeds after a storm.

Mr. Bingley describes an animal of this kind, which he kept by him for some time alive; it had more than four thousand tentacula on the under sides of the rays. These it frequently retracted, and again pushed out, as a snail does its horns; and by means of them it was enabled firmly to adhere to the dish containing the salt-water in which it was kept. Whenever he touched the tentacula with his finger, all those of that ray or limb were gradually withdrawn, but those of the other rays were not in the least affected by it.

There are many other kinds of Star-fishes, especially in warm climates. Amongst our native species we may notice the _Great Sun Star_ (_Solaster papposa_) with a large disc and thirteen short rays; the _Luidia fragilissima_ with five long rays, which it usually casts off immediately on finding itself in danger, so as to render it a most difficult matter to obtain perfect specimens of this species. The _Feathered Star_ (_Comatula rosacea_) is also deserving of mention.--This is a small species, with the arms distinct from the body as in the last species and jointed, but furnished with numerous slender jointed tentacles which give them the appearance of plumes. There are ten of these arms and the number of little calcareous joints contained in them is most astonishing. The small cuplike body of the Feather Star bears other slender jointed appendages, by means of which the creature clings to the rocks with its mouth and arms directed upwards; and in the young state it is even supported on a jointed stalk, from which it eventually casts itself free.

THE SEA-URCHIN. (_Echinus miliaris._)

THIS animal, which lodges in the cavities of rocks just beneath low-water mark, on most of the British coasts, is nearly of a globular shape, not much unlike that of an orange, having its shell marked into ten partitions, with rows of projections like beads, which divide it. On the outside of the shell there are a great number of sharp, moveable spines, of a dull violet and greenish colour, curiously articulated, like balls and sockets, with tubercles on the surface, and connected by strong ligaments to the skin or epidermis with which the shell is covered. The mouth is situated in the under part, and is armed with five strong and sharpened teeth. The animal can move from place to place by means of its contractile tubular feet and its spines; but its movements are slow and laborious. So tenacious of life are the Sea-urchins, that the ancients, according to Appian, believed that the body retained life even when cut to pieces.

“If in the sea the mangled parts you cast,
The conscious pieces to their fellows haste;
Again they aptly join, their whole compose,
Move as before, nor life nor vigour lose.”

In Marseilles, and some other towns on the continent, the Sea-urchin is exposed for sale in the markets, as oysters are with us, and is eaten boiled as an egg. The Romans adopted it as food, and dressed it with vinegar, mead, parsley, and mint.

ZOOPHYTES.

ZOOPHYTES were long supposed to hold a middle station between animals and vegetables. Most of them, deprived altogether of the power of locomotion, are fixed by stems that take root in the crevices of rocks, among sand, or in such other situations as Nature has destined for their abode; these, by degrees, send off branches, till at length some of them attain the size and extent of large shrubs. The Zoophytes were placed by Linnæus in two divisions. The stony branches of the first division, which have the general appellation of coral, are full of hollow cells, which are habitations of the animals. The next division consists of such Zoophytes as have softer, fleshy, or horny, stems, and in which the individual polypes are, as it were, amalgamated with their common plant-like habitation.

Magnified branch, exhibiting the Animals. Gorgonia Nobilis.

THE RED CORAL.]

THE CORAL, or Gorgonia, is a hard, stony, branched, and cylindrical substance, which is formed at the bottom of the sea by animals called polyps, or, to use the Latin and now established term, _polypi_. The whole form a living mass, or polypidom, all the polypi in which are united under one skin, and have one common stomach. Each of these polypi resides in a distinct cell; they are generally dormant during winter, and like the blossoms of plants, push forth buds, and expand in the summer season. The stems and branches of the Gorgoniæ, which are of a somewhat horny and flexible nature, may be considered as the true skeletons of the nests of the sea polypi, being covered with a fleshy or pulpy substance, the surface of which is porous. These pores are the mouths or openings of the cells, in which the polypi are lodged; and it is the number, disposition, and varied structure of these, in addition to the general aspect of the plant-like nest of habitations, that constitute the distinguishing difference of the species.

The bone of the Red Coral constitutes that beautiful and much esteemed production, the true or red coral of the jewellers. It is found in the Mediterranean, Adriatic, and Red Sea, and appears to be nowhere more abundant than in the seas about Marseilles, Corsica, Sicily, the coasts of Africa, and in the vicinity of Barbary; where the Coral fisheries are carried on with great spirit, and prove very lucrative. It is equal in hardness and durability to the most compact marble; and these qualities, in addition to its beautiful texture and colour, have rendered it valuable in all ages. Thus in the book of Job, “No mention shall be made of corals, or of pearls; for the price of wisdom is above rubies.”

Travellers in tropical lands often speak of the exquisite beauty of the coral beds that lie at the bottom of the ocean. The water is so clear in those regions, that these wonderful formations are clearly visible at a great depth, growing like stony forests, mingled with waving seaweeds of many brilliant dyes.

The mode of obtaining Coral is by a very simple machine, consisting of two strong bars of wood or iron, tied across each other, with a weight suspending from their centre of union. Each of the bars is loosely surrounded, throughout its whole length, with twisted hemp; and, at the extremity, there is a small open net. The machine is suspended by a rope, and dragged along those rocks where the Coral is most abundant: and such as is broken off either becomes entangled in the hemp, or falls into the nets.

Coral is bought by weight, and its value increases according to its size. Beads of large size are worth about forty shillings an ounce, whilst small ones do not sell for more than four shillings. Large pieces of Coral are sometimes cut into balls, and exported to China, to be worn as insignia in the caps of officers of state. These, if perfectly sound and of good colour, and upwards of an inch in diameter, have been known to produce in that market, as much as three to four hundred pounds sterling each. There are extant many beautiful pieces of sculpture in coral, as this substance has in all ages been considered an admirable material on which to exhibit the artist’s taste and skill. Probably the finest specimen of sculptured Coral yet known is a chess-board and men in the palace of the Tuileries.

The Chinese have, within the last few years, succeeded in cutting coral beads of much smaller dimension than has hitherto been effected by any European artist. These, which are not larger than small pins’ heads, are called Seed Coral, and are now imported from China into this country, in very considerable quantity for necklaces. There are modes by which Coral may be so exactly imitated, that without a close inspection, it is sometimes impossible to detect the counterfeit.

STONY CORALS.

THE RED CORAL, just described, belongs to the section of zoophytes called Asteroida by Cuvier, in which the surface of the polypidom is fleshy, and each polypus has only eight arms. The polypi which form the massive stony corals of the tropical reefs, are furnished with numerous tentacles, and resemble in their general conformation the Sea Anemones which are so well known now-a-days as inhabitants of aquaria. The coral consists of a deposit of carbonate of lime, and each polypus dwells in a cell which exhibits a number of thin stony rays nearly meeting in the middle. The masses of coral differ exceedingly in size, some consisting of the habitations of only two or three polypi, whilst others are the gradual production of a vast and constantly succeeding population; some form branched trees and shrubs of the most various and elegant forms, others grow in solid masses, but all, when living, present a most beautiful appearance from the charming and often brilliant diversity of colours with which they are adorned.

In the Pacific Ocean several of the coral reefs are extremely beautiful, and the voyager is astonished with the curious and fantastic forms of the various marine productions of which they are composed. Wheat-sheaves, mushrooms, cabbage leaves, with innumerable plants and flowers, are vividly represented by different kinds of Coral, and glow beneath the water in brilliant tints of brown and purple, white or green; each with a peculiar form and shade of colouring, equal in richness and variety to the most beautiful productions of the vegetable world. Corals and fungi start from between the fissures of the rocks; while large portions of the former, in a dead state, connected into a solid mass, of a dull white colour, compose the stone-work of the reef. Solid masses, termed negro heads, of different dusky hues, and generally dry and blackened by exposure to the weather, are also occasionally conspicuous. Even these are not without ornament, for nature delights in the variety of her decorations. They are studded with small shells, and beautifully marked with outlines expressive of their origin. The edges of the reefs, particularly those exposed to the waves, partake of a considerable degree of lightness, and form small coves and caverns, the resort of live corals, sponges, sea-eggs, and trefangs, or sea traces, (valued in China, for their invigorating quality,) and enormous cockles, which are scarcely to be distinguished from the rock, excepting when they suddenly close their shells, and discharge living fountains, which rise to the height of four or five feet.

With regard to the formation of coral reefs, it has been conjectured, from the appearance of the low islands in some parts of the South Sea and Indian Ocean (where they occur in rows or groups, while they are totally absent in other parts of the same seas), that Coral animals rear their habitations on marine shoals, or, to speak more properly, at or near the top of sub-marine mountains. As it is known, however, that the polypes can only build their coral within a small distance of the surface of the sea, and the water is often of immense depth close to the coral reefs, it has been supposed that in the Pacific Ocean, where the greater part of the Coral reefs and islands are met with, the bottom of the sea has been gradually undergoing changes, deepening in some places and becoming shallower in others, and by this supposition most of the peculiarities of the Coral reefs and islands may easily be accounted for. Where reefs are formed the bottom is generally sinking; islands indicate that the bottom is stationary or rising. In the latter case, when the Corals approach close to the surface, floating substances of every kind are caught by their stony tree-like fabrics, till at length a solid mass of rock is formed, which gradually advances to the surface of the water. The deposits of the ocean no longer tenaciously adhere, but remain in a loose state, and form what is termed by mariners a key upon the summit of the reef; while the sea, by throwing up sand and mud on the top of these animal rocks, progressively raises them above its level. The new island, for such it may now be called, is soon visited by sea-birds; plants successively appear, and carpet the sterile soil with a luxuriant covering. As these decay, vegetable mould is gradually deposited; cocoa-nuts, or some floating seeds, flung on shore by the impetuosity of the waves, take root, and soon begin to grow; land-birds, attracted by the verdant appearance of the bank, fly thither in quest of provisions, and deposit the seeds of shrubs and trees; every high tide and every gale adds some new treasure: the appearance of an island is gradually assumed, and at length man comes to take possession.

1. Coral of the Astrea _annanas_.

2. Animal of the Caryophyllia _solitaria_.

3. Animal of the Tubipora _musica_.

4. Animal and dwelling of the Cellepora _hyalina_.

5. Animal and central axis of the Gorgonia _patula_.
]

SPONGE is a substance of a soft, light, porous, and elastic nature, which is found adhering to rocks at the bottom of the sea, in several parts of the Mediterranean, and particularly near the islands of the Grecian Archipelago; and which, in its natural state, is filled with animal jelly. The general uses of Sponge, arising from its ready absorption of fluids, and distension by moisture, are well known and of great importance. It is collected from rocks, in water five or six fathoms deep, chiefly by divers. When first taken from the sea, it has a strong and fishy smell, from the animal matter it contains, of which it is divested by being washed in clear water. No other preparation than this is requisite previously to its being packed up for exportation and sale. The growth of Sponge is so rapid, that it is frequently found in perfection on rocks, from which, only two years before, it had been entirely cleared.

As they are never designed to move from their places of abode, the surface of the Sponges is covered with innumerable small apertures or pores, communicating with a network of fine canals, which permeate every part of the substance and convey to the minute and simple creatures which form the living part of this curious compound animal, the food and water necessary for their support and respiration. These fine canals unite into larger passages, leading to orifices of considerable size usually placed on prominences of the surface; from these the water streams forth with such force, according to some observers, as to be perceptible by the eye.

The inherent chemical properties of this curious Zoophyte are very remarkable. When a Sponge has been immersed for fourteen or sixteen days in nitric acid (diluted with three parts of distilled water) it becomes nearly transparent, and when touched with ammonia, assumes a deep orange colour, inclining to a brownish red. But if much softened by the acid, the whole fabric immediately disappears, on being immersed in ammonia, and forms a deep orange-coloured solution. A Sponge, when boiled, gives out a considerable portion of animal jelly. The infusion of a small quantity of oak bark causes this to fall to the bottom of the vessel, as a sediment, and so entirely changes the nature of the Sponge, that, when dry, it crumbles between the fingers; and, when moist, it may be torn like wetted paper. In this state we should naturally conclude that it is entirely useless: but no; the operations of chemistry resemble a magic wand. Boil the same in water, with caustic potash, its latent qualities will be called forth; and, behold, a deposition of animal soap!

THE FRESH-WATER POLYPI AND THEIR MARINE ALLIES. (_Hydroida._)

THESE are two species, which will fully illustrate the nature of the whole tribe. They are found in clear waters, and may generally be seen in small ditches and trenches of fields, especially in the months of April and May. They affix themselves to the under-parts of leaves, and to the stalks of such vegetables as happen to grow in the same water; and feed on the various species of small worms and other aquatic animals within their reach. When any of these pass near a Polyp, the latter suddenly catches it with its arms, and dragging it to its mouth, swallows it by degrees, much in the same manner as a snake gorges its prey. Two Polypi may occasionally be seen in the act of seizing the same worm at different ends, and dragging it in opposite directions with great force. It sometimes happens, that while one is swallowing the end it has seized, the other is employed in the same manner; and thus they continue swallowing, each his part, until their mouths meet. They then rest for some time in this situation, till the worm breaks between them, and each goes off with his share. But sometimes when the mouths of both are thus joined together a combat ensues, and the largest Polyp usually swallows his antagonist; the animal thus swallowed, however, seems to be a gainer by its misfortune, as after it has lain in the conqueror’s body for about an hour it issues unhurt, and often in possession of the prey that had been the original cause of contention. The remains of the animal, on which the Polyp feeds, are evacuated at the mouth, the only opening in the body. The species are multiplied by a kind of vegetation, one or two, or even more young ones, emerging gradually from the sides of the parent animal; and these young ones are frequently again prolific before they drop off; so that it is no uncommon thing to see two or three generations at once on the same Polyp. But the most astonishing fact respecting this animal is, that if a Polyp be cut in pieces, it is not destroyed, but is multiplied by dissection. It may be cut in every direction that fancy can suggest, and even into very minute divisions, and not only the parent stock will remain uninjured, but every section will become an animal. Even when turned inside out, it suffers no material injury; for, in that state it will soon begin to take food, and to perform all its other natural functions.

M. Trembley, of Geneva, ascertained that different portions of one Polyp could be engrafted on another. Two transverse sections brought into contact will quickly unite and form one animal, though each section should belong to a different species. The head of one species may be engrafted on the body of another. When one Polyp is introduced by the tail into another’s body, the two heads unite and form one individual. Pursuing these strange operations, M. Trembley gave scope to his fancy by repeatedly splitting the head and part of the body; he thus formed hydras more complicated than ever struck the imagination of the most romantic fabulist.

Though so difficult to destroy by division, all the Polyps, even those which form the corals, may be easily killed by depriving them of moisture, when they soon shrivel up, and the tissue of their skins is completely destroyed.

OF these Fresh-water Polypi, only a few kinds are known, but the sea nourishes a multitude of species which closely resemble the Hydras in their structure, from hence called Hydroid Polyps by Cuvier and many other naturalists. Most of these are compound creatures, of the kind shown in the above engraving, of which many species may be found on all our shores. A horny tube runs branching over the surface of a seaweed, or some other object, and from this, at intervals, rise slender stalks, often branched in the most elegant manner. Upon the delicate branches we find little horny cups, each of which is the habitation of a tiny Polyp, furnished with a mouth and stomach, and with a circlet of slender arms to enable it to capture its prey. Other species are enclosed only in a soft membrane, but all rise from creeping roots.

BESIDES the Polypi just mentioned as nearly related to the fresh-water _Hydra_ and those forming the different kinds of Corals, the sea produces a vast number of other Zoophytes, the commonest kinds of which are well known as Sea Anemones. These animals are found adhering to rocks on all shores; they consist of a rather thick column, the base of which forms an adhesive disc, while its summit, which is also a disc, shows a puckered mouth in the centre surrounded by several rows oftentacles. The tentacles are sometimes short and stout, sometimes long and slender; they are generally adorned with vivid or delicate colours, often disposed in rings and contrasting beautifully with the colours of the stem and disc. In their expanded state they present a close resemblance to a flower, and indeed vie with many flowers in beauty; hence the name of _Animal Flowers_ was given to them formerly, and has now given place to that of Sea Anemones, although they are rather to be compared with those composite flowers in which numerous petal-like flowerets radiate from a central disc. When contracted, the Sea Anemones resemble soft knobs or buttons, with a depression at the top.

In describing the Stony Corals, the fact has been mentioned that the Polyps, which may be regarded as the architects of those extraordinary structures, are very similar to the Sea Anemones. In the latter, the cavity surrounding the central stomach is partially divided into chambers, by partitions, which run inwards from the circumference towards the centre; in the Coral Polyps each of these partitions produces a stony plate in its substance, and these plates form the rays which occupy the interior of the Polyp-cell.

The Sea Anemones move slowly along by the action of their adhering disc, somewhat in the same way that a snail or slug crawls upon the ground. Their food is obtained by means of the tentacles which give them their beautiful flower-like character, and to render them efficient organs for this purpose they are endowed with a singular provision. The skin of the tentacles, and, indeed, of most parts of the Sea Anemone is filled with little cells or vesicles, each containing a spiral thread, which when touched instantly darts forth, and penetrates the body coming in contact with it. In this way, if a worm, a small fish, or any other soft animal touches the tentacles of an Anemone, it is instantly transfixed with innumerable delicate darts, which not only assist the tentacles in holding the destined prey, but also seem to exercise a sort of numbing influence upon the victim, deadening his struggles and rendering him an easy conquest. He is then speedily passed by the tentacles to the orifice of the mouth, and swallowed without mercy.

One of the commonest kinds of these Polyps is the _Mesembryanthemum_ (_Actinia Mesembryanthemum_), a large, usually liver-coloured species, with a row of blue warts round the margin just outside the tentacles. It is found abundantly on the rocks of our Southern coast especially. The _Thick-horned Anemone_ (_Actinia_ or _Brusodes crassicornis_) is another large and fine species, usually of a red colour, with very thick tentacles, which are generally white with pinkish bands.--The _Sea Cereus_ (_Anthea Cereus_) has long slender tentacles, which are not retracted in the same way as those of the Sea Anemones generally. The tentacles are usually tipped with a pink or purple tint; they are constantly waving about in the water in search of prey; and instantly seize upon any creature that passes over them.--The _Parasitic Anemone_ (_Actinia parasitica_) and the _Cloak Anemone_ (_Adamsia palliata_) always attach themselves to univalve shells which are occupied by Hermit Crabs.

JELLY FISHES.

THE animals commonly known as Jelly Fishes are free-swimming Radiata; they were described by Cuvier and most succeeding naturalists under the name of _Acalephæ_, from a Greek word signifying “_nettles_,” because many of them produce a stinging sensation when they come in contact with the skin. Their name in several languages signifies “Sea Nettles.” The Acalephæ of Cuvier are now regarded as belonging to the same class as the Hydroid Polyps.

The common Medusa (_Medusa amita_), which may serve as an example of this group, is found in great abundance round our coasts; it is of a circular form, convex above, concave beneath, like an umbrella, the stick of which is represented by a thick stalk, containing the mouth and stomach, and terminated by four long arms for seizing the animal’s food. The skin of these, and of the body and its appendages generally is full of the thread-cells described as occurring in the Sea Anemones, and it is to these that the stinging power of the Medusæ is due. The motion of the Medusæ through the water is effected by the alternate expansion and contraction of its umbrella, which is slightly inclined in the direction towards which the creature is moving, and it is a most beautiful sight to look down upon a fleet of these animals, all advancing in the same direction at a depth of two or three feet in the water, as may often be seen in fine weather at the mouths of our rivers.

At first sight it may be thought that the Medusæ have but little in common with the Hydroid or any other Polyps, but it has been fully proved by late researches that the young animal produced from the egg of the Medusa is a regular Polyp, which adheres by its base, and obtains its food by the agency of a crown of tentacles surrounding its mouth; nay, it even propagates in this form by pushing out buds exactly in the manner described in the case of the fresh-water Hydra. In course of time, however, the body of this Polyp becomes elongated, and its surface is marked into rings, the grooves separating which gradually become deeper until the whole body breaks up into a number of saucer-like segments, each of which becomes a Medusa. How fully does this extraordinary mode of reproduction show that the wonders of the Creator are no less striking in the lowest than in the highest of his creatures, and that for all, from the highest to the lowest, the same prescient care has been exercised, the same goodness evinced. Verily, we may follow the pious example of the great Linnæus, and exclaim with the Psalmist, “O Lord, how manifold are thy works! in wisdom hast thou made them all.”