Chapter XXXVII: Part II: The Inhabitants of the Sea (10)

Every one knows the common Star-fish, with its lanceolate arms; its generally orange-coloured back, thickly set with tubercles, and the pale under-surface, with its rows of feet, feelers, or suckers, which serve both for locomotion and the seizure of food.

When one of these creatures is placed on its back, in a plate filled with sea-water, it is exceedingly curious to watch the activity which those numberless sucking feet display. At first the star-fish is motionless; for, offended by the rough handling it has undergone, the feet have all shrunk into the body; but soon they are seen to emerge like so many little worms from their holes, and to grope backwards and forwards through the water, evidently seeking the nearest ground to lay hold of. Those that reach it first immediately affix their suckers, and, by contracting, draw a portion of the body after them, so as to enable others to attach themselves, until, pulley being added to pulley, their united power is sufficient to restore the star-fish to its natural position.

The upper tuberculated surface is shown, with some of the spines of
the under surface projecting at the sides of the rays. At one of the
angles between the rays, on the right side, is seen the eccentric
calcareous plate, or madreporic tubercle, which indicates the
existence of a bilateral symmetry.]

This act of volition is surely remarkable enough in so simple an animal, which scarcely possesses the rudiments of a nervous system, but the simple mechanism by which the suckers are put into motion is still more wonderful. Each of these little organs is tubular, and connected with a globular vesicle filled with an aqueous fluid, and contained within the body of the star-fish immediately beneath the hole from which the sucker issues. When the animal wishes to protrude its feet, each vesicle forcibly contracts, and, propelling the fluid into the corresponding sucker, causes its extension; and, when it desires to withdraw them, a contraction of the suckers drives back the fluid into the expanding vesicles. The internal walls of the suckers and their vessels are furnished with vibratory cilia, and by this simple means a continual circulation of the fluid they contain goes on within them.

Numerous species of star-fishes are so very common in our waters, that in many places the sea-bottom is literally paved with them. They likewise abounded in the primeval ocean, for deep beds of carboniferous limestone and vast strata of the triassic muschelkalk are often formed by the accumulation of little else than the skeletons of Encrinites and Pentacrinites, which, unlike the sea-stars which every storm drifts upon our shores, did not move about freely, but were affixed to a slender flexible stalk, composed of numerous calcareous joints connected together by a fleshy coat. The feathered bifurcated arms of the Crinoids are unprovided with suckers, which would have been perfectly useless to creatures not destined to pursue their game to any distance, but passively to receive the nutriment which the current of sea-water set in motion by their richly-ciliated pinnules conveys to the mouth. These beautiful creatures were formerly supposed to be nearly extinct, for up to within the last few years only two living stalked crinoids were known in the ocean of the present period, but the dredge has latterly brought up new and remarkably fine species from depths of more than 2000 fathoms, and there is every reason to believe that these animals still form an important element in the abyssal fauna.[S]

[Footnote S: See page 420.]

Of freely-swimming Crinoids but one single representative is known in the northern seas, the Rosy Feather-star (_Comatula rosacea_), whose long and delicately fringed rays and deep rose colour dotted with brown may serve to give us an idea of the beauty of the submarine landscapes where _Pentacrinus Wyville-Thomsoni_ or _Bathycrinus gracilis_ abound. During the earlier stage of its existence, the comatula is attached to a stalk; a discovery for which science is indebted to Mr. T. V. Thompson, who in 1823 dredged in the Cove of Cork a singular little pedunculated crinoid animal (_Pentacrinus europæus_), which he found attached to the stems of zoophytes. It measured about three-fourths of an inch in height, and resembled a minute _comatula_ mounted on the stalk of a _pentacrinus_. When this pygmy representative of the ancient lily-stars was first dragged up from its submarine haunts, it created a great sensation among naturalists, as it was the first recent animal of the encrinite kind which had ever been seen in the seas of Europe. At first it was supposed to be a distinct species, but Mr. Thompson, by carefully following it through all the stages of its growth, succeeded in proving that it was merely the hitherto unnoticed young of the rosy feather-star.

This elegant crinoid is found all round our coasts, and its range extends from Norway to the shores of the Mediterranean. In swimming, the movements of its arms exactly resemble the alternating stroke given by the medusa to the liquid element, and have the same effect, causing the animal to raise itself from the bottom and to advance back foremost, even more rapidly than the medusa. When dying, either in fresh water or in spirits, it emits a most beautiful purple colour, which tinges the liquid in which it is killed.

The _Ophiuridæ_, or _snake-stars_, are essentially distinguished from the true _star-fishes_ by the long serpent or worm-like arms, which are appended to their round, depressed, urchin-like bodies. They have no true suckers with which to walk, their progression being effected (and with great facility) by the twisting or wriggling of their arms, which are moreover in many species furnished with spines on the sides, assisting locomotion over a flat surface. These arms are very different from those of the true star-fishes, which are lobes of the animal's body, whereas the arms of the Ophiuridæ are mere processes attached or superadded to the body.

These animals are very generally distributed through the seas of our earth, both of its northern and southern hemispheres, but are found largest in the tropical ocean. In our own waters they are very abundant, and are among the most curious and beautiful game pursued by the dredger.

The British Ophiuridæ belong to two generic types, that of the _Ophiuræ_ and that of the _Euryales_. The former, to which the sand and brittle-stars belong, have simple arms; the latter, arms ramifying into many processes.

The rays of the Sand-stars have a whip-like or lizard-tail appearance, while those of the Brittle-stars look like so many centipedes or annelides attached at regular distances round a little sea-urchin. We have ten native brittle-stars, the most common of which (_Ophiocoma rosula_, Forbes) is also one of the handsomest, presenting every variety of variegation, and the most splendid displays of vivid hues arranged in beautiful patterns. Not often are two specimens found coloured alike. It is the most brittle of all brittle-stars, separating itself into pieces with wonderful quickness and ease. Touch it, and it flings away an arm; hold it, and in a moment not an arm remains attached to the body. "The common brittle-star," says Edward Forbes, "often congregates in great numbers on the edges of scallop-banks, and I have seen a large dredge come up completely filled with them; a most curious sight, for when the dredge was emptied, these little creatures, writhing with the strangest contortions, crept about in all directions, often flinging their arms in broken pieces around them; and their snake-like and threatening attitudes were by no means relished by the boatmen, who anxiously asked permission to shovel them overboard, superstitiously remarking that the things weren't altogether right."

Fancy the naturalist's vexation, who has no other means of preserving a brittle-star entire than by quickly plunging it into cold fresh water, which acts as a poison on the Ophiuræ as well as on most other marine animals, and kills them so instantaneously that even the most brittle species have no time to make the contraction necessary to break off their rays.

The _Ophiocoma rosula_ seems to be equally abundant on all parts of the coast of Britain and Ireland. It is fond of rocky places, and grows in Shetland to a much larger size than elsewhere. It is said to prey on little shells and crabs, and is greatly relished by the cod in its turn, great numbers being often found in the stomach of that voracious fish.

The Scotch or Shetland Argus (_Euryale verrucosum_, Lamarck), a very rare animal, of which the adjoining wood-cut represents a segment, is the only British _Euryale_. It measures a foot or more across, and its singular aspect has long excited admiration among naturalists. "So odd a creature as this," remarks Bradley in his "Works of Nature," "is well worth the contemplation of such curious persons as live near the sea, where every day they have subjects enow to employ their curiosity and improve their understanding." Grew says that "as he swims he spreads and stretches out all his branches to their full length, and so soon as he perceives his prey within his reach, he hooks them all in, and so takes it as it were in a net."

The British species of true star-fishes may be arranged under four families. The _Urasters_ are distinguished from all others by having four rows of suckers in each of the avenues which groove the under surface of their rounded rays. In consequence of the great number of these singular organs, the under surface of a living cross-fish presents a sight truly curious and wonderful. Hundreds of worm-like suckers, extending and contracting, coiling and feeling about, each apparently acting independently of the others, give the idea rather of an assemblage of polypi than of essential parts of _one_ animal. They are sensitive in the extreme, for, if we touch one of those singular tubes when outstretched, all those in its neighbourhood are thrown into a state of agitation; and when it shrinks from our touch, changing from a lengthy fibre to a little shrunk tubercle, some of its neighbours, as if partaking in its fears, contract themselves in like manner.

The common Cross-fish (_Uraster rubens_) abounds on most parts of our shores, so as in some places to be used for manure in large quantities. "It is a sworn enemy to oysters, and as it is frequently found with one or more of its rays broken off, the fishermen fancy that it loses them in consequence of its oyster-hunting propensities; that it insinuates an arm into the incautious oyster's gape, with the intent of whipping out its prey, but that sometimes the apathetic mollusk proves more than a match for its radiate enemy, and closing on him, holds him fast by the proffered finger; whereupon the cross-fish preferring amputation and freedom to captivity and dying of an oyster, like some defeated warrior flings his arms away, glad to purchase the safety of the remaining whole by the reparable loss of a part, as it has the power of reproducing the broken rays.

"There is, however, reason to think that the cross-fish destroys his prey in a very different manner from that just narrated; for star-fishes are not unfrequently found feeding on shell-fish, enfolding their prey within their arms, and seeming to suck it out of its shell with their mouths, pouting out the lobes of the stomach, which they are able to project in the manner of a proboscis. Possibly the stomach secretes an acrid and poisonous fluid, which, by paralysing the shell-fish, opens the way to its soft and fleshy parts."--_Forbes's Star Fishes._

The _Solasters_ are "suns in the system of sea-stars," and are entitled to this distinguished rank among the marine constellations by their many rays and brilliant hues. The _Solaster papposa_, or common Sun-star, with rays varying in number from twelve to fifteen, is one of the commonest, and at the same time handsomest, of all the British species. Sometimes the whole upper surface is deep purple, and frequently the disk is red, and the rays white tipped with red. It grows to a considerable size, having been found eleven inches broad.

The Goniasters, or Cushion-stars, are distinguished from the allied species by their pentagonal form. One of the most singular of our native species is the Birdsfoot Sea-star (_Palmipes membranaceus_), being the thinnest and flattest of all its class. When alive it is flexible, like a piece of leather, and a person who had never seen it before would be apt to mistake it for the torn off dorsal integument of some gibbous goniaster. The colour is white, with a red centre and five red rays, proceeding one to each angle. The whole upper surface is covered with tufts of minute spines arranged in rows.

The Asteriæ, with their stellate body and flat rays, are very different in aspect from the Goniasters. The Butt-thorn (_Asterias aurantiaca_) owes its name to one of those strange superstitions which originate in some inexplicable manner, and are handed down by one credulous generation to the next. "The first taken by the fishermen at Scarborough is carefully made a prisoner, and placed on a seat at the stern of the boat. When they hook a butt (halibut) they immediately give the poor star-fish its liberty and commit it to its native element; but if their fishery is unsuccessful it is left to perish, and may eventually enrich the cabinet of some industrious collector."

To the family of the Asteriæ belongs also the Ling-thorn (_Luidia fragilissima_), the largest, and one of the most interesting of our British species. When full grown, it measures two feet across, and would appear to exceed that size occasionally, judging from fragments. The rays are from five to seven in number, quite flat, and generally five times as long as the disk is broad. The colour is brick-red above, varying in intensity, the under surface being straw-coloured. The wonderful power which the Luidia possesses, not merely of casting away its arms entire, but of breaking them voluntarily into little pieces with great rapidity, approximates it to the brittle-stars, and renders the preservation of a perfect specimen a very difficult matter.

"The first time I ever took one of these creatures," says Edward Forbes, "I succeeded in getting it into the boat entire. Never having seen one before, and quite unconscious of its suicidal powers, I spread it out on a rowing-bench, the better to admire its form and colours. On attempting to move it for preservation, to my horror and disappointment I found only an assemblage of rejected members. My conservative endeavours were all neutralised by its destructive exertions, and it is now badly represented in my cabinet by an armless disk and a diskless arm. Next time I went to dredge on the same spot, determined not to be cheated out of a specimen in such a way a second time, I brought with me a bucket of cold fresh water, to which article star-fishes have a great antipathy. As I expected, a luidia came up in the dredge, a most gorgeous specimen. As it does not generally break up before it is raised above the surface of the sea, cautiously and anxiously I sunk my bucket to a level with the dredge's mouth, and proceeded in the most gentle manner to introduce luidia to the purer element. Whether the cold air was too much for him, or the sight of the bucket too terrific, I know not, but in a moment he proceeded to dissolve his corporation, and at every mesh of the dredge his fragments were seen escaping. In despair I grasped at the largest, and brought up the extremity of an arm with its terminating eye, the spinous eyelid of which opened and closed with something exceedingly like a wink of derision."

The Sea-star might be called a flattened sea-urchin, with radiated lobes, and the Sea-urchin, a contracted or condensed sea-star, so near is their relationship. In both we find the same radiating construction, in which the number five is so conspicuous, and in both also the rows of suckers, which, starting from a centre, are set into motion by a similar mechanism, and used for the same purpose. In all the sea-urchins finally, and in many of the sea-stars, we find the surface of the body covered with numerous exceedingly minute, two- or three-forked pincers, that perpetually move from side to side, and open and shut without intermission. These active little organs, which have been named _Pedicellariæ_, were formerly supposed to be parasites, working on their own account, but they are now almost universally recognised as organs subservient to the nutrition of the animal, and destined to seize the food floating by, and to convey it to the mouth, one passing it to the other. Even in their outward appearance, the sea-urchins are not so very different from the sea-stars as would be imagined on seeing a Butt-thorn near a globular urchin, for both orders approach each other by gradations; thus, the Goniasters, with their cushion-shaped disks and shortened rays, approximate very much in shape to the sea-urchins; and among the latter we also find a gradual progression from the flattened to the globular form. Still there are notable differences between the two classes. Thus in the sea-urchins the digestive organs form a tube with two openings, while in the true sea-stars they have but one single orifice. Their mode of life is, however, identical.

On the right side covered with spines, on the left the spines removed.]

The Echinidæ move forward by means of the joint action of their suckers and spines, using the former in the manner of the true star-fishes, and the latter as the snake-stars. They also make use of the spines, which move in sockets, to bury themselves in the fine sand, where they find security against many enemies.

Some species even entomb themselves pholas-like in stone, inhabiting cavities or depressions in rocks, corresponding to their size, and evidently formed by themselves. Bennett describes each cavity of the edible _Echinus lividus_ as circular, agreeing in form with the urchin within it, and so deep as to embrace more than two-thirds of the bulk of the inhabitant. It is large enough to admit of the creature's rising a little, but not of its coming out easily. The echinus adheres so firmly to this cavity by its suckers, as to be forced from it with extreme difficulty when alive. On the coasts of the county of Clare thousands may be seen lodged in the rock, their purple spines and regular forms presenting a most beautiful appearance on the bottoms of the grey limestone rock-pools. How the boring is performed has, like many other secrets, not yet been settled by naturalists. The first perforation is most likely effected by means of the teeth, and then the rock softened by some secreted solvent.

Sea-urchins are found in all seas, but as they are extremely difficult to preserve, and many of them have such long and delicate spines that it is almost impossible to procure perfect specimens, probably not one tithe of their species is known.

On our coasts the common "egg-urchin" affords the poor a somewhat scanty repast; but, throughout the Mediterranean, its greater size, and also that of its allies, _Echinus melo_ and _E. sardicus_, render them, when "in egg," important articles of food. In Sicily these animals are in season about the full moon of March; there the _E. esculentus_ is still called the "King of Urchins;" whilst the larger melon-urchin is popularly considered to be its mother. The size and abundance of these edible species are among the striking peculiarities of the fish markets of the Mediterranean sea-board.

The calcareous shell of the "sea-urchin" seems, at first sight, to be composed of one simple crust, but proves, on nearer inspection, to be a masterpiece of mosaic consisting of several hundred parts, mostly pentagonal. These are so closely united that their junctions are hardly visible, but on allowing the shell to macerate for some days in fresh water, it falls to pieces. This complicated structure is by no means a mere architectural fancy, a useless exuberance of ornament, but essentially necessary to the requirements of the animal's growth. A simple hard crust would not have been capable of distension, whereas a complicated shell, such as the sea-urchin possesses, can grow in the same ratio as the internal parts, by continual deposits on the edges of the individual pieces. On closely examining a living sea-urchin, we find the whole surface of the shell and spines covered with a delicate skin, which, in spite of their close connexion, penetrates into the intervals of the several pieces. This membrane secretes the chalk of which the shell is composed, and deposits fresh layers on the edges of the plates, so that in this manner the shell continually widens until the animal has attained its perfect size. The spines are secreted in the same manner, and show under the microscope an admirable beauty and regularity of structure. So bountifully has the great Architect of worlds provided for the poor insignificant sea-urchin!

The dental apparatus of the animal--the so-called lantern of Aristotle--is another masterpiece in its way. Fancy five triangular bones or jaws, each provided with a long, projecting, movable tooth. A complicated muscular system sets the whole machinery going, and enables the jaws to play up and down, and across, so that a more effective grinding-mill can scarcely be imagined.

A. Two sockets with teeth, of Echinus esculentus. B. Single socket
with its tooth viewed on the outside.]

The _Holothuriæ_, or Sea-cucumbers, may be regarded in one light as soft sea-urchins, and in another as approximating to the Annelides or worms. Their suckers are similar to those of the true star-fishes and sea-urchins. Besides progression by means of these organs, they move, like annelides, by the extension and contraction of their bodies. The mouth is surrounded by plumose tentacula, the number of which, _when they are complete_, is always a multiple of five. They all have the power of changing their shapes in the strangest manner, sometimes elongating themselves like worms, sometimes contracting the middle of their bodies, so as to give themselves the shape of an hour-glass, and then again blowing themselves up with water, so as to be perfectly globular.

The great Sea-cucumber is the largest of all the known European species, and probably one of the largest _Cucumeriæ_ in the world, measuring when at rest fully one foot, and capable of extending itself to the length of three. Under the influence of terror, it dismembers itself in the strangest manner. Having no arms or legs to throw off, like its relations the luidia and the brittle-star, it simply disgorges its viscera, and manages to live without a stomach; no doubt a much greater feat than if it contrived to live without a head. According to the late Sir James Dalyell, the lost parts are capable of regeneration, even if the process of disgorgement went so far as to leave but an empty sac behind. Considering the facility with which the sea-cucumber separates itself from its digestive organs, it is the more to be wondered how it tolerates the presence of a very remarkable parasite, a fish belonging to the genus _Fierasfer_, and about six inches long. This most impudent and intrusive comrade enters the mouth of the cucumber, and, as the stomach is too small for his reception, tears its sides, quartering himself without ceremony between the viscera and the outer skin. The reason for choosing this strange abode is as yet an enigma.

The _Holothuriæ_, which in our part of the globe are very little noticed, play a much more important part in the Indian Ocean, where they are caught by millions, and, under the name of _Trepang_ or _Biche de mer_, brought to the markets of China and Cochin-China. Hundreds of praos are annually fitted out in the ports of the Sunda Islands for the gathering of trepang; and sailing with help of the western monsoon to the eastern parts of the Indian Archipelago, or along the northern coast of Australia, return home again by favour of the eastern monsoon. The bays of the inhospitable treeless shores of tropical New Holland, the abode of a few half-starved barbarians, are enlivened for a few months by the presence of the trepang fishers.

"During my excursions round Raffles Bay," says Dumont d'Urville, ("Voyage to the South Pole,") "I had remarked here and there small heaps of stones surrounding a circular space. Their use remained a mystery until the Malayan fishers arrived. Scarce had their praos cast anchor, when without loss of time they landed large iron kettles, about three feet in diameter, and placed them on the stone heaps, the purpose of which at once became clear to me. Close to this extemporised kitchen they then erected a shed on four bamboo stakes, most likely for the purpose of drying the holothurias in case of bad weather. Towards evening, all preliminaries were finished, and the following morning we paid a visit to the fishermen, who gave us a friendly reception. Each prao had thirty-seven men on board, and carried six boats, which we found busily engaged in fishing. Seven or eight Malays, almost entirely naked, were diving near the ship, to look for trepang at the bottom of the sea. The skipper alone stood upright, and surveyed their labours with the keen eye of a master. A burning sun scorched the dripping heads of the divers, seemingly without incommoding them; no European would have been able to pursue the work for any length of time. It was about noon, and the skipper told us this was the best time for fishing, as the higher the sun, the more distinctly the diver is able to distinguish the trepang crawling at the bottom. Scarce had they thrown their booty into the boat when they disappeared again under the water, and as soon as a boat was sufficiently laden, it was instantly conveyed to the shore, and succeeded by another.

"The holothuria of Raffles Bay is about six inches long, and two inches thick. It forms a large cylindrical fleshy mass, almost without any outward sign of an organ, and as it creeps very slowly along is easily caught. The essential qualities of a good fisherman are great expertness in diving, and a sharp eye to distinguish the holothurias from the similarly coloured sea-bottom.

"The trepang is first thrown into a kettle filled with boiling sea-water. After a few minutes, it is taken out of its hot-bath and ripped open with a knife to cleanse it of its intestines. It is then thrown into a second kettle, where a small quantity of water and the torrefied rind of a mimosa produce dense vapours. This is done to smoke the trepang for better preservation. Finally, it is dried in the sun, or in case of bad weather under the above-mentioned shed. I tasted the trepang, and found it had some resemblance to lobster. In the China market the Malays sell it to the dealers for about fifteen rupees the picul of 125 pounds. From the earliest times, the Malays have possessed the monopoly of this trade in those parts, and Europeans will never be able to deprive them of it, as the economy of their outfit and the extreme moderation of their wants forbid all competition. About four in the afternoon the Malays had terminated their work. In less than half an hour the kettles and utensils were brought on board, and before night-fall we saw the praos vanish from our sight."

The inhabitants of the island of Waigiou, to the north of New Guinea, prepare the trepang in the Malay manner, and barter it for cotton and woollen stuffs, which are brought to them by some Chinese junks. "In every hut," says Lesson, "we found great heaps of this dried leathery substance, which has no particular taste to recommend it, and is so highly esteemed by the Chinese for no other reason than because they ascribe to it,--as to some other gelatinous substances, as agar-agar, shark-fins, and edible bird's nests,--peculiar invigorating properties, by means of which their enervated bodies are rendered fit for new excesses."

The Feejee islanders have the reputation of being the greatest cannibals and the most perfidious savages of the whole Pacific, yet the trepang fishery attracts many American and European speculators to that dangerous archipelago. Captain Wilkes, of the United States Exploring Expedition, found there a countryman, Captain Eagleston, who had been successful in more than one of these expeditions, and obligingly communicated to him all the particulars of his adventurous trade. There are six valuable sorts of biche de mer, or trepang; the most esteemed is found on the reefs one or two fathoms deep, where it is caught by diving. The inferior sorts occur on reefs which are dry, or nearly so, at low water, where they are picked up by the natives, who also fish the biche de mer on rocky coral bottoms by the light of the moon or of torches, as they come forth by night to feed. The most lucrative fisheries are on the northern side of Viti Levu. They require a large building for drying, with rows of double staging, on which reeds are placed. Slow fires are kept up by natives underneath, about fifteen hands being required to do the ordinary work of a house.

Before beginning, the services of some chief must be secured, who undertakes the building of the house, and sets his dependants at work to fish. The usual price is a whale's tooth for a hogshead of the animals just as they are taken on the reef; but they are also bought with muskets, powder, balls, vermilion, blue beads, and cotton cloth of the same colour. When the animals are brought on shore, they are measured into bins containing about fifty hogsheads, where they remain until next day. They are then cut along the belly for a length of three or four inches, taking care not to cut too deep, as this would cause the fish to spread open, which would diminish its value. They are then thrown into boilers, two men attending each pot, and relieving each other, so that the work may go on night and day. No water need be added, as the fish itself yields moisture enough to prevent burning. After draining on a platform for about an hour, they are taken to the house and laid four inches deep upon the lower battens, and afterwards upon the upper ones, where they remain three or four days. Before being taken on board they are carefully picked, all damp pieces being removed. They are stowed in bulk, and sold in Manilla or Canton by the picul, which brings from fifteen to twenty-five dollars. In this manner Captain Eagleston had collected in the course of seven months, and at a trifling expense, a cargo of 1200 piculs, worth about 25,000 dollars. The outfit is small, but the risk is great, as no insurance can be effected; and it requires no small activity and enterprise to conduct this trade. A thorough knowledge of native character is essential to success, and the utmost vigilance and caution must always be observed to prevent surprise, or avoid difficulties.

No large canoes should ever be allowed to remain alongside the vessel, and a chief of high rank should be kept on board as a hostage. That these precautions are by no means unnecessary, is proved by the frequent attempts of the savages to cut off small vessels trading on their coasts. One of the most frequent methods is to dive and lay hold of the cable; this, when the wind blows fresh to the shore, is cut, in order that the vessel may drift upon it, or in other cases a rope is attached to the cable by which the vessel may be dragged ashore. The time chosen is just before daylight. The moment the vessel touches the land, it is treated as a prize sent by the gods, and the crew murdered, roasted, and devoured.

CHAP. XVII.

CŒLENTERATA.

POLYPS AND JELLY-FISHES.

Thread-cells or Urticating
Organs.--Sertulariæ.--Campanulariadæ.--Hydrozoie
Acalephæ.--Medusidæ.--Lucernariadæ.--Calycophoridæ.--The
Velella.--The Portuguese Man-of-war.--Anecdote of a
Prussian Sailor.--Alternating Fixed and Free-swimming
Generations of Hydrozoa.--Actinozoa.--Ctenophora.--Their
Beautiful Construction.--Sea-anemones.--Dead Man's
Toes.--Sea-pens.--Sea-rods.--Red Coral.--Coral Fishery.--Isis
hippuris.--Tropical Lithophytes.--History of the Coral
Islands.--Darwin's Theory of their Formation.--The progress of their
Growth above the level of the Sea.

Despite the low rank they occupy in the hierarchy of animal life, the Cœlenterata, comprising the numerous families of the Jelly-fishes and Polyps, play a most important part in the household of the ocean, for the sea is frequently covered for miles and miles with their incalculable hosts, and whole archipelagos and continents are fringed with the calcareous structures they raise from the bottom of the deep.

Their organisation is more simple than that of the preceding classes, for they have neither the complex intestinal tube of the polyzoa or the sea-urchins nor the jointed rays or arms of the star-fishes; their whole digestive apparatus is but a simple sac, and their instincts are reduced to the mere prehension of the food that the currents bring within reach of their tentacles, or to the retraction of these organs when exposed to a hostile attack.

But, simple as they are, they have been provided by Nature with a comparatively formidable weapon in those remarkable "thread-cells," or urticating organs, which are so constantly met with in their integuments, and chiefly in their tentacles.

The thread-cells are composed of a double-walled sac having its open extremity produced into a short sheath terminating in a long thread. A number of barbs or hooks are sometimes disposed spirally around the sheath, the thread itself being often delicately serrated. Under pressure or irritation the thread-cell suddenly breaks, its fluid escapes, and the delicate thread is so rapidly projected that the eye is utterly unable to follow the process. The violent protrusion of this barbed missile, along with the acrid secretion of the cell, causes many a worm or crustacean of equal or superior strength, that might have gone forth as victor from the struggle of life, to succumb to the cœlenterate, and is even in many cases exceedingly irritating to the human skin. Besides enabling its possessor to derive his subsistence from animals whose activity, as compared with his own, might be supposed to have removed them altogether out of the reach of danger, these stings serve also as admirable weapons of defence, and many a rapacious crab or annelide that would willingly have feasted upon a sea-anemone is no doubt repelled by the venomous properties of its urticating tentacles.

_a_, _e_, _f_. Threads and thread-cells of _Caryophyllia Smithii_.
_b._ Thread-cell of _Corynactis Allmani_.
_c._ Peculiar receptacle of _Willsia stellata_, containing thread-cells.
_d._ A single thread-cell of the same.
_g._ Thread-cell of _Actinia crassicornis_.--(All magnified.)
]

The Cœlenterata have been subdivided into two great classes: the Hydrozoa, in which the wall of the digestive sac is not separated from that of the cavity of the body, and the Actinozoa, in which the stomach forms a distinct bag separated from the wall of the cavity of the body by an intervening space, subdivided into chambers by a series of vertical partitions. Each of these two classes comprises a number of families of various forms and habits of life. Thus among the Hydrozoa, with whom I begin my brief survey of cœlenterate life, some are of a compound nature (Sertularidæ, &c.), and, having once settled, remain permanently attached to the site of their future existence; while others (Rhizostomidæ, &c.) continue freely to roam through the water, and others again appear in the various stages of their development either as sessile polyps or as free-swimming Medusæ.

The sertularian tribes are remarkable for the elegance of their forms, resembling feathers more or less stiff and angular, more or less flexible and plumose. Their bleached skeletons are among the commonest objects thrown out by the waves, and so plant-like is their appearance and manner of growth that, like the Flustræ, they might easily be mistaken for sea-weeds.

_a._ Skeleton (natural size).
_b._ Portion of the same, highly magnified.
_κ._ _Cœnosarc_, or common trunk.
_π′._ _Hydrotheca_, or protective envelope of individual polyp.
_ρ′._ _Gonoblastidium_, or reproductive germ or body.
]

Originally produced from a single ovulum, every species, by the evolution of a succession of buds, after an order peculiar to each, grows up to a populous colony, and simultaneously with its growth the fibres by which it is rooted extend, and at uncertain intervals give existence to similar bodies, whence new polypiferous shoots take their origin, for these root fibres are full of the same medullary substance with the rest of the body. Thus the graceful sea-fir (_Sertularia cupressina_), the largest of our native species, may attain a height of two or three feet, and bear on its branches no less than 100,000 distinct microscopical polypi, each with its own crown of tentacles, and each of these armed with numerous thread-cells, as formidable in their way as the crustacean's claw or the annelide's embrace. But though each polyp has a certain share of independence yet its body is continuous with the more fluid pulp that fills the branches and stem of the common trunk, and by this means all the polyps of it are connected together by a living thread, and made to constitute a family whose workings are all regulated by one harmonious instinct. Each of these plant-like structures may therefore be considered as one animal furnished with a multitude of armed heads and mouths, and in all the other compound cœlenterates we find a similar organisation. All the soft parts of a sertularian polypary are enclosed in a horny sheath (_hydrosoma_) which develops peculiar cup-shaped processes (_hydrothecæ_) for the protection of each individual polyp, and capsules for the reproductive bodies (_gonoblastidia_) in which the ova are produced. The various modifications of form and structure of the polyps, of their hydrothecæ and gonoblastidia, give rise to a number of families, genera, and species. Thus in the Sertulariæ the polypites are sessile, biserial, alternate, or paired; sessile and uniserial in the Plumulariæ, and stalked in the Campanulariadæ.

_a._ _Laomedea neglecta_, natural size.
_b._ Portion of the same, magnified.
_c._ Reproductive body of _Campanularia volubilis_.
_e._ Reproductive body of _C. syringa_.
]

The free-swimming Jelly-fishes, or Acalephæ, as they have been named by Aristotle on account of the stinging properties due to their urticating cells, are likewise among the commonest objects left upon our shores by the retreating tide. When stranded, they appear like gelatinous masses, disgusting to the sight; but these shapeless objects were beautiful while they moved along in their own element, and their simple organisation shows no less the masterhand of the Creator than the complex structure of the higher stages of animal existence. With the exception of the Ctenophora, they all belong to the hydrozoic class, and from the great diversity of their structure have been ranged under four orders, Medusidæ, Lucernaridæ, Calycophoridæ, and Physophoridæ.

_a._ Medusid seen in profile.
_b._ The same viewed from below.
_c._ Its polypite.
_d._ Part of its marginal canal, and other structures in
connection therewith.
ν. Disk or swimming organ.
π. Polypite.
ψ. Veil.
τ. Tentacle.
χ. Radiating canal.
χ′. Marginal canal.
ω. Reproductive organ.
ο′. Coloured spot.
ο″. Marginal vesicle.
]

The Medusidæ are distinguished by their globular or bell-shaped disc, which by its alternate contractions and expansions forces them forward through the water. By contracting the whole or only part of its disc, the medusa has it in its power to direct its movements, and while thus swimming along with the convex side of the disc directed forwards, and its oral lobes and tentacles following behind like "streamers long and gay," it may well rank among the most elegant children of the sea.

From the roof of the disc a single polypite is suspended, whose mouth, generally produced into four lobes, though in some forms it is much more divided, passes into the central cavity (stomach) of the swimming organ, from which canals (either four in number, or multiples of four) radiate to join a circular vessel surrounding the margin of the bell. A shelf-like membrane or veil, extending around the margin, and highly contractile, assists locomotion by narrowing more or less the aperture of the bell, and thus concentrating its efforts upon a narrower space. More or less numerous tentacles generally depend from the margin, and around it are disposed two kinds of remarkable bodies--"vesicles" and "pigment spots," or "eye-specks"--which are supposed to be able to communicate the impressions of light and sound. This complexity of organisation in creatures which Réaumur contemptuously styled mere lumps of animated jelly is all the more wonderful when we consider that they consist almost entirely of water, and shrink to a mere nothing when abandoned by their vital power. Thus of a medusa originally weighing many pounds but few traces remain after death; the ground is covered with a light varnish; all the rest has been absorbed by the thirsty sands.

_a._ _Aequorea formosa_, seen in profile.
_b._ The same, viewed from above.
_c._ Upper view of _Willsia stellata_.
_d._ _Slabberia conica._
_e._ Portion of the marginal canal of _Tiaropsis Pattersonii_.
_f._ Polypite of _Bougainvillea dinema_.
_g._ Part of its marginal canal.
_h._ _Steenstrupia Owenii._ (_a_, _b_, and _d_ are about the natural
size; the others are magnified.)
]

The oceanic or free-swimming forms of the Lucernaridæ resemble the Medusidæ by their bell-shaped umbrella, but differ from them by their internal structure, by the absence of a marginal veil, by the nature of their canal system and marginal bodies, and by their mode of development. The radiating canals, never less than eight in number, send off numerous branches, which form a very intricate network, and the vesicles and pigment-spots, here united into a single organ, termed the lithocyst, are each protected externally by a sort of hood, whence these jelly-fishes have been named "Stegonophthalmia," or "covered-eyed," by Forbes, to distinguish them from the naked-eyed "Gymnophthalmia," or Medusidæ. The Pelagidæ (Chrysaora), which form one of the divisions of this group, are simple, and have their margin surrounded with tentacles like the Medusidæ, while the Rhizostomidæ have no marginal tentacles, and consist of numerous polyps studding the trunks of a dependent tree. These animals have consequently no central mouth, but hundreds of little mouths all active for the welfare of the community.

_a._ _Rhizostoma pulmo._
_b._ _Chrysaora hysoscella._
_c._ Its lithocyst.--(All reduced.)
]

The sessile Lucernaridæ differ from the other members of the order by the narrow disc or stalk which serves to fix their body when at rest. Their quadrangular mouth is in the centre of the umbrella expansion, and round the margin of the cup arise a number of short tentacles, disposed in eight or nine tufts in Lucernaria, and forming one continuous series in Carduella.

Though generally preferring to lie at anchor, the Lucernaridæ are able to detach themselves, and to swim in an inverted position by the slowly repeated movements of their cup-like umbrella. When in a state of expansion, few marine creatures exceed them in beauty and singularity of form; when contracted, they are shapeless, and easily overlooked. "Their mode of progression," says Mr. Couch, "differs under different circumstances. If intending to move to any great distance, they do so by loosening their attachments, and then, by various and active contortions, they waft themselves away till they meet with any obstruction, where they rest; and if the situation suits them, they fix themselves; if not, they move on in the same manner to some other spot. If the change be only for a short distance, as from one part of a leaf to another, they bend their campanulate rims, and bring the tentacula in contact with the jaws, and by them adhere to it. The foot-stalk is then loosened and thrown forward and twirled about till it meets with a place to suit it; it is then fixed, and the tentacula are loosened, and in this way they move from one spot to another. Sometimes they advance like the Actiniæ, by a gliding motion of the stalk. In taking their prey, they remain fixed with their tentacula expanded, and if any minute substance comes in contact with any of the tufts, that tuft contracts, and is turned to the mouth, while the others remain expanded watching for prey."

The Calycophoridæ are distinguished by the cup-shaped swimming organs, which form the most prominent part of their body. Generally transparent like glass, their course upon distant inspection is only revealed by the bright tints of some of their appendages. In Diphyes, the type of the group, the two cups (ν, ν′′) fit into each other so as to form a more or less perfect close canal. The common stem of the numerous polyp colony freely glides up and down the chamber thus formed, into which it can be completely retracted, and along its sides are placed the several appendages of the compound creature, consisting chiefly of polypites (π), tentacles, and organs of reproduction. Large specimens of Diphyes attain, when fully extended, a length of several inches, the stem giving support to at least fifty different polypites. The other genera of the order exhibit a great variety in the form and arrangement of their various parts; thus, in Vogtia, each of the swimming organs (ν) is produced into five points, of which the three upper are much longer and stronger than the two lower. The individual polyps (π), large in size, but few in number, are congregated immediately under the swimming apparatus, and are provided with long and formidable tentacula.

In the Physophoridæ the basal end of the common polyp stem is modified so as to form a float or aëriform sac, which is, however, extremely different in shape, structure, and size in the various families. In the Velellæ, the float, whose under surface is studded, besides one larger central polypite, with numerous small nutritive, reproductive, and tentacular bodies, forms a horizontal disc traversed by a diagonal triangular crest, and divided into numerous hollow chambers. Thus equipped, the semi-transparent velella, beautifully tinged with ultramarine, sails on the surface of the warmer seas, but the currents of the Gulf Stream, and the westerly winds, frequently drift it to the coast of Ireland, where it is often found on the beach, entangled in masses of sea-weed. Of the vast numbers in which it sometimes occurs, Herr von Kittlitz relates an interesting instance in his "Travels to Russian America and Micronesia." "Having passed 30° N. lat. in the Pacific, the sea was suddenly found covered with myriads of Velellæ, of a size somewhat greater than the Atlantic species." Two days long the ship sailed through these floating masses, when suddenly the scene changed, and large clusters of barnacles appeared, which, having no doubt devoured the soft parts of the Velellæ, now invested their horny skeletons. As the ship advanced, the number of the barnacle clusters augmented, which, to judge from the various sizes of the individuals, must have taken some time for their formation, and were apparently destined to increase until the final destruction of the Velellæ hosts, into which, from their greater weight, they were continually drifting deeper and deeper by the action of the currents. Again two or three days elapsed, and as the surface of the sea occupied by both species of animals extended at the least over four degrees of latitude, a faint idea may be formed of their numbers. Shoals of dolphins and sperm-whales were busy exterminating the barnacles, as these had devoured the Velellæ. The whole scene was an example on the grandest scale of the destruction and regeneration perpetually going on in the wastes of the ocean.

_a_. _Velella spirans_, somewhat enlarged.
_b._ One of its smaller polypites, much magnified.
ν. Crest.
λ. Liver.
ο. Mouth of polypite.
δ. Its digestive cavity.
φ′. Rounded elevations, containing thread-cells.
ρ. Medusiform zoöids.
]

α. Pneumatophore, or float-bladder.
π. Polypites.
τ. Tentacles.
]

The Physaliæ, which far surpass the Velellæ in size and beauty, are also inhabitants of the warmer seas, where the _Physalia caravella_, or "Portuguese man-of-war," is the mariner's admiration. On a large float-bladder eight or nine inches long and three inches broad, whose transparent crystal shines in every shade of purple and azure, rises a vertical comb, the upper border of which sparkles with fiery red. This beautiful float has a small opening at either end, and strong muscular walls, so that by their contraction its cavity can be considerably diminished. And thus partly by the escape of air forced out through the openings, and partly by the compression of what remains, the specific gravity is so much altered as to admit of the animal's sinking into the deep when danger threatens. Numerous polyps proceed from the lower surface, accompanied by tentacles having a sac-like extension at their base, and hanging down in beautifully blue and violet coloured locks or streamers. When fully extended, these tentacles form fishing lines fifteen or sixteen feet long, which, as their thread-cells are uncommonly large, at once paralyse the resistance of the fish or cephalopod they meet with. Then rolling together, they convey the senseless prey to the numerous mouths of the compound animal, which, sucking like leeches, pump out its nutritious juices. In this manner the greedy physalia devours many a bonito or flying-fish of a size far superior to its own, and such is the corrosive power of its tentacles that even man is punished with excruciating pains when heedlessly or ignorantly he comes within their reach. "One day," says Dutertre in his "History of the Antilles," "as I was sailing in a small boat, I saw a physalia, and as I was anxious to examine it more closely, I tried to get hold of it. But scarcely had I stretched out my hand when it was suddenly enveloped by a net of tentacles, and after the first impression of cold (for the animal has a cold touch) it seemed as if my arm had been plunged up to the shoulder in a caldron of boiling oil, so that I screamed with pain." In his journey round the world, Dr. Meyen also relates the case of a sailor who jumped overboard to catch a physalia. But scarce had he come within reach of its tentacles when the excruciating pain almost deprived him of sensation, and he was with great difficulty hauled out of the water. A severe fever was the consequence, and his life was for some time despaired of.

Several of the Physophoridæ are provided, besides the float, with swimming-bells (_nectocalyces_) and peculiar appendages or bracteæ (_hydrophyllia_), which, overlapping the polypites, serve for their protection. The graceful _Athorybia rosacea_ possesses from twenty to forty of these organs inserted in two or three circlets immediately below the pneumatocyst, and above a much smaller number of polypites.

It has the power of alternately raising and depressing them so as to render them agents of propulsion.

The Physophoræ have no hydrophyllia, but their swimming-bells are considerably developed, and serve as powerful instruments of locomotion. They are also provided with certain processes termed "hydrocysts," which some observers appear disposed to regard as organs of touch. Such are but a few of the numerous genera of the Physophoridæ.

α. Pneumatophore.
ν. Swimming-bells.
φ. Hydrocysts.
π. Polypites.
τ. Tentacles.
]

Of the jelly-fishes in general it may be remarked that, though they are denizens of the frigid as well as of the temperate and tropical seas, their beauty increases on advancing towards the equator, for while the Medusæ in our latitudes are generally dull and obscure, those of the torrid zone appear in all the splendour of the azure, golden-yellow, or ruby-red tints which distinguish the birds and fishes of those sunny regions. They are indeed of no immediate use to man, but their indirect services are not to be despised. They partly nourish the colossal whale, and thus, converted into oil, attract thousands of hardy seamen to the icy seas; numberless Crustacea and molluscs also live upon their hosts, and are in their turn devoured by the mighty herring shoals, whose capture gives employment and wealth to whole nations of fishermen.

_a._ Ova with gelatinous investment.
_b_ and _c_. Free ova.
_d._ Young Hydratuba developed therefrom.
_e._ The same with eight tentacles.
_f._ Hydratuba in its ordinary condition.
_g_, _h_. More advanced forms, with constrictions.
_i._ A specimen undergoing fission, in which the tentacles are seen
to arise from below the constricted portion, while its upper
segments separate and become free-swimming zoöids (_k_).
]

Armed with that wonderful instrument, the microscope, naturalists have been taught to disunite in many cases animals which from their external resemblance were formerly supposed to belong to the same class or family; and to join others to all appearances extremely dissimilar. Thus the Bryozoa have been detached from the polyps, in spite of their similitude of growth, while the roaming and fixed Hydrozoa have been found in many cases to be but alternating generations or various phases of development of the same animal. Take, for instance, _Chrysaora hysoscella_ (see preceding figure, page 351), one of our commonest jelly-fishes. The ova this free-swimming creature produces might naturally be supposed to develop themselves into equally free-swimming Chrysaoræ; but instead of this they soon become attached, and grow into a colony of sessile Hydratubæ, as, at this stage of their career, they have been termed. For years they may thus continue, but then the evolutions shown in the annexed illustration take place until free-swimming zoöids are detached, which eventually become similar to the huge Chrysaora, from one of whose ova the primitive hydratube was produced.