My Tropic Isle Part 8

There was a decided swing of one of the spikes in the direction of the fish, and decided agitation among the hundreds of minute tentacles. When I, in the interests of remorseless truth, placed the fish in the anemone it was immediately held fast, the activity on the part of the tubes subsiding with an air of satisfaction at the same moment.

It is well known that sea anemones do a.s.similate such robust and rich diet as living fish. If one's finger is presented the spikelets adhere to it. I cannot describe the sensation as seizure, for it is all too delicate for that; but at least one is conscious of a faint sucking pull. If the finger is rudely withdrawn, some of the tentacles which have taken a firm hold are torn away. Again, the animal is often found apparently asleep, for it is languid and listless, and will not respond to the bait of a finger, however coaxingly presented.

There is another giant anemone (DISCOMA HADDONI) known to the blacks as "pootah-pootah," whose inner, reflexed, convoluted edges are covered with tentacles of brown with yellow terminals. This is friendly to fish--at any, rate to one species. It is the landlord or host of one of the prettiest fish of all the wide, wide sea, and seems proud of the company of its guest, and the fish is so dependent upon its host as to be quite helpless apart from it. The fish (AMPHIPRION PERCULA) "intel-intel" of the blacks, is said to be commensal (literally, dining at the same table with its host), as distinguished from the parasite, which lives on its host.

The good-fellowship between the dainty fish--resplendent in carmine, with a broad collar, and waist-band of silvery lavender (or rather silver shot with lavender) and outlined with purple--and the great anemone is apparent. If the finger is presented to any part of the latter, it becomes adherent; or if the anemone is not in the mood for food, it curls and shrinks away with a repulsive demeanour. But the beautiful fish on the least alarm retires within the many folds of its host, entirely disappearing, presently to peep out again shyly at the intruder.

It is almost as elusive as a sunbeam, and most difficult to catch, for if the anemone is disturbed it contracts its folds, and shrinks away, offering inviolable sanctuary. If the fish be disa.s.sociated from its host, it soon dies. It cannot live apart, though the anemone, as far as can be judged from outward appearances, endures the separation without a pang.

However, it is safe to a.s.sert that the a.s.sociation between the stolid anemone and the painted fish--only an inch and a half long--is for their mutual welfare, the fish attracting microscopic food to its host. And why should one anemone greedily seize a fish, and another find pleasure in the companionship of one of the most beautiful and delicate of the tribe?

This hospitable anemone occasionally takes another lodger--very frail and beautiful. All that is visible on casual inspection is an irregular smear of watery, translucent violet, flitting about in a.s.sociation with disjointed threads--stiff, erratic, and delicately white. There is no apparent connection between the spectral patch of colour and the animated threads, though they are in company. If, determined to investigate the mystery, the finger is presented, the colour evades it. It is conscious and abhors the touch of man. Follow it up in the pellucid water, and make of your hand a scoop, and you will find that you have captured, not a phantom but a prawn, compact of one bewildering blotch--and that is a word of doubtful propriety in connection with so elfin an organism--a mere shadow tinted the palest violet, and transparencies, with legs and antennae frail as silken threads.

"Substance might be called what shadow seemed, For each seemed either."

So far I have never seen this lovely lodger in the same anemone with the painted fish. The latter, perhaps, admires it too ardently and literally.

Another marvel, the sea-hare (APLYSIA), is a crudely wedge-shaped body but incomparable in its ruggedness to that or any other model, and the colour of mud and sand and of coral, dead and sea-stained. It reposes, with its back flush with the surface, beside a block of coral or stone defiantly indistinguishable from the ocean floor--a stolid, solid, inert creature, eight or ten inches long, the under part smooth, presenting the appearance of wet chamois-leather, and irresponsive to touch--"the mother tongue of all the senses." Ugly, loathsome, and tough of texture, it is so helpless that if it is placed on the sand it is extremely doubtful whether of its own volition it could regain its natural position. The surge of the sea might roll it over, and it might then be able to regain the grovelling att.i.tude essential to life. Otherwise, I am inclined to think fatal results would follow the mere placing of the creature sideways on the sand. It seems to possess but the feeblest spark of life, and yet it has its sentiments and love for its kind, for often three or four are huddled together. And how, it may be asked, is this creature, so apt at concealment and so completely disguised, made visible to human eyes?

The answer is that if by chance the animal is disturbed it makes a supreme effort at further concealment, and that impulse--perfect as it may be when set in opposition to the wit of the creature's nervous and apprehensive enemies--reveals it most boldly to man. From a funnel-shaped opening between two obscure flaps on the back--ordinarily invisible--there is emitted a gush of liquid, royal purple in hue, which stains the sea with an impenetrable dye for yards around. The colour, which is delightfully gorgeous, mingles with the water in jets and curling feathery sprays, enchanting the beholder with unique and ever-changing shapes until a glorious cloud is created and he forgets the ugliness and forgives the humility of the originator in the enjoyment of an artistic treat. If the cloud which Jupiter a.s.sumed was of the imperial tone and of the fascinating fashion which the groveller in the mud creates, Aegina would have been superfeminine had she not joyously surrendered. Between the neutral tints of the squalid sprawler and the fluid which it excretes the contrast is so surprising that one involuntarily raises his hat by way of apology for any slighting thoughts which may have arisen from first and imperfect acquaintance.

There are grounds for the entertainment of the belief that the ejected fluid not only effectually conceals the scarcely discernible animal but that it harshly affects the sensibilities of fish.

In a partially submerged coral grotto were two small spotted sharks (Wobbegong, CROSSORHINUS sp.) notoriously sluggish and averse from eviction from their quarters during daylight. The larger callously disregarded the tickling of a light fish spear, but lashed out vigorously when a decisive prod was administered. In its flurry it must have disturbed one of the dye-secreting molluscs, which had escaped my notice, for in a few seconds the water was richly imbued. Thereupon both the sharks began to manifest great uneasiness, and eventually with fl.u.s.ter and splashing they worked among the fissures of the coral and shot out into the unimpregnated sea. The sharks seemed to find the presence of the forlorn groveller in the mud unendurable when it stained the water red, though apparently indifferent to its presence as long, as it remained quiescent, which facts lend confirmation to the popular opinion that the fluid possesses a caustic-like principle violently irritative to the skin.

And why should this uncouth creature with scarcely more of life than a lump of coral have within it a fountain filled with Tyrian dye? Why?

Because it has enemies; and though it seems to be SANS mouth, SANS eyes, SANS ears, SANS everything it is instinct with the first law of Nature--self-preservation.

A fairly common inhabitant of the sandy shallows diversifying the coral reef is a slim snake (? AIPYSINAS FUSCUS), sand-coloured, with a conspicuous dark brown stock, defined with white edgings, a whitish nose and pectoral fins so large as to remind one of those defiant collars which Gladstone was wont to wear with such excellent effect. Blacks invariably give the snake and its retreat a wide berth on the principle enunciated by Josh Billings: "Wen I see a snaik's hed sticking out of a hole I sez that hole belongs to that snaik." Among them this species has the reputation of attacking off-hand whosoever disturbs it, and of being provided with deadly venom. My experience, however, bids me say that the pretty snake has the typical dread of the family of man, which dread expresses itself in frenzied efforts to get out of the way when suddenly molested. For the most part it lives in a neat hole, oubliette-shaped, and in its eagerness to locate and reach its retreat it darts about with a nimbleness which almost eludes perception. These frantic quarterings, I believe, led to the opinion that the snake is specially savage, whereas it is merely exceptionally nervous and eager for the security of its home. Twice recently when I have startled one in an enclosed pool it has darted hither and thither in extreme excitement, even pa.s.sing between my legs without offering any violence or venom, and has eventually disappeared in a miniature maelstrom of mud, as the reptile often does.

Like that lively fellow of whom Chaucer tells:

"He is heer and there, He is so variant, he bideth nowhere."

d.i.c.kens had in his mind a similarly elusive character when he wrote: "You look at him and there he is. You look again--and there he isn't."

This habit of furiously seeking a lair might pa.s.s casually but for an astonishing detail, of which I was not well a.s.sured until it was confirmed by repeated observations and by knowledge current among the blacks. When the scared snake descends into its own well-defined well, very little disturbance and no discoloration of the water takes place.

But when in desperation it disappears down a haphazard hole, a dense little cloud of sediment is created. By careful watching I discovered that the snake entered its home head first, but in any other hole the tail had precedence, and that the frantic wriggling as it bored its way down caused the obscuration. Moreover the snake--as subtle as any beast of the field--first detects a befitting temporary retreat from apparent or fancied danger, and then deliberately turns and enters tail first. Does the fact justify the conclusion that the creature, in the moment intervening between the detection of a present refuge in time of trouble and its dignified retreat thereinto, calculates the possibility that the unfamiliar habitation may be so narrow as to prevent the act of turning round? Does this sea-snake match its wonderful nimbleness of body with an equally wonderful nimbleness of brain? I do not presume to theorise on such a conundrum of Nature, but mention an undoubted fact for others to ponder.

One of the salt sea snakes is distinguished by its odd, deceptive shape--a broad, flattened tail whence the body consistently diminishes to the head, which is the thinnest part. Other aquatic snakes have paddle-shaped tails.

Another singular denizen of the reef is a species of Acrozoanthus (?)--a compound animal having a single body and several heads. The body is contained in a perpendicular, parchment-like, splay-footed tube a foot and a half or two feet long, whence the heads obtrude alternately as buds along a growing branch. Many of the tubes are vacant--the skeletons of the departed. From those which are occupied the heads appear as bosses of polished malachite veined and fringed with dusky purple, and yellow-centred.

Sp.a.w.n OF THE SEA

"The dewdrop slips into the shining sea."

So Edwin Arnold. Here is an observation ill.u.s.trating the manner in which certain pellucid sea-drops materialise and ultimately shed themselves as living organisms "into the shining sea."

On November 6, 1908, the sea tossed up on the beach an exceptionally large and absolutely perfect specimen of the egg-cl.u.s.ter of that s.p.a.cious and useful mollusc known as the Bailer Sh.e.l.l (MELO DIADEMA or CYMBIUM FLAMMEUM). Its measurements were: length, 16 in.; circ.u.mference at base, 12 in.; at middle, 11 in.; at apex 7 1/8 in. It weighed 1 lb. and comprised 126 distinct capsules. The photograph presents a candid likeness.

During the same month and the first two weeks of December portions of several other egg-cl.u.s.ters came ash.o.r.e, and as they were in nicely graduated stages of development I was enabled to indulge in an exceptionally entertaining study--no less than the observation of the transformation of glistening fluid into solid matter and life. In pa.s.sing it may be mentioned that the first and the last two months of the year appear to const.i.tute the period when the offspring of the species see the light of day, proving that the natural impulses of some molluscs are subject to rule and regulation similarly to those of birds and other terrestrial forms.

Each of the capsules composing the cl.u.s.ter is a cone with the apex free and interior, while the base is external and adherent to its immediate neighbours, but not completely so throughout its circ.u.mference. It follows, therefore, that the cl.u.s.ter of capsules is hollow and that water flushes it throughout. In appearance it resembles a combination of the pineapple and the corncob, and to the base a portion of the coral-stem to which it had been anch.o.r.ed by its considerate parent was firmly attached.

When the cl.u.s.ter of capsules (the substance of which is tough, semi-transparent, gelatine, opal-tinted, soon to be sea-stained a yellowish green) is slowly expelled from the parent's body--I have been witness to the birth--each contains about one-sixth ounce of vital element, fluid and glistening. Physical changes in this protoplasm manifest themselves in the course of a few days. The central portion becomes a little less fluid, and from an inchoate blur a resemblance to a diaphanous sh.e.l.l develops and floats, cloud-like, in a perfectly limpid atmosphere. Gradually it becomes denser though still translucent, as it seemingly absorbs some of the fluid by which it is surrounded. The model of the future animal, exact even to the dainty contours and furrows around that which represents the spire of the ultimate sh.e.l.l, is still without trace of visible organs. That, however, its substance is highly complex is obvious, for as imperceptible development progresses the exterior is transformed into a substance resembling rice tissue-paper--an infinitely fragile covering--which from day to day insensibly toughens in texture and becomes separate from the animal. Faint opaque, transverse ribs are at this stage apparent, though disappearing later on. Opacity is primarily manifested at the aperture of the infant mollusc where a seeming resemblance to an operculum forms, possibly for the protection of vital organs during nascency. This plaque of frail armour is, however, soon dismantled, and of course much more happens in the never-ceasing process than is revealed to the uninitiated.

As the calcareous envelope becomes opaque and solid, the animal within loses its transparent delicacy, and coincidentally the apex of the capsule opens slightly. In the meantime the fluid contents have disappeared, as if the animal had resulted from its solidification. The animal, too, is a very easy fit in its compartment, and incapable, in its extreme fragility of withstanding the pressure of a finger. Now it begins to increase rapidly in bulk and st.u.r.diness; the sh.e.l.l becomes hard, and as the exit widens it screws its way out of a very ragged cradle, emerging sound and whole as a bee from its cell, all its organs equipped to ply their respective offices.

With pardonable affectation of vanity it has finally fitted itself for appearance in public by the a.s.sumption of three or four buff and brown decorations upon its milk-white sh.e.l.l, which quickly blend into a pattern varying in individuals, of blotches and clouds in brown, yellow, and white. In maturity the mollusc weighs several pounds, its sh.e.l.l has a capacity for as much as two gallons of water, and is coloured uniformly buff, while in old age infantile milk-white rea.s.serts itself.

It is not for such as I am in respect of the teachings of science to say whether the development of the perfect animal from a few drops of translucent jelly--as free from earthly leaven as a dewdrop--is to be more distinctly traced, in the case of this huge mollusc than in other elementary forms. All that it becomes an unversed student of life's mysteries to suggest is that this example gives bold advertis.e.m.e.nt to the marvellous process.

Many of the secrets of life are written in script so cryptic and obscure that none but the wise and greatly skilled may decipher it, and they only, when aided by the special equipment which science supplies. In this case the firm but facile miracle is recorded in words that he that runs may read. Independent of microscope the unskilled observer may trace continuity in the transformation of jelly to life.

The sea-drop, lovely in its purity, knowing neither blemish nor flaw, becomes an animal with form and features distinctive from all others, with all essential organs, means of locomotion, its appet.i.te, its dislikes, its care of itself, its love for its kind, its inherent malice towards its enemies--all evolved in a brief period from the concentrated essence of life.

"If, as is believed, the development of the perfect animal from protoplasm epitomises the series of changes which represent the successive forms through which its ancestors pa.s.sed in the process of evolution" (these are the words of Professor Francis Darwin) what a graphic, what a luminous demonstration of evolution is here presented!

In a brief previous reference to this mollusc it was stated that the infants in their separate capsules were in a state of progressive development from the base to the apex of the cl.u.s.ter, those in the base being the farther advanced. Investigations lead to a revision of such statement. No favour seems to be enjoyed by first-born capsules.

Development is equable and orderly, but as in other forms of life the contents of certain capsules seem to start into being with a more vigorous initial impulse than others, and these mature the more speedily.

A st.u.r.dy infant may be s.c.r.e.w.i.n.g its way out of its cradle, while in a weakly and degenerate brother alongside the thrills of life may be far less imperative.

The pictures ill.u.s.trate isolated scenes in the life-history of the mollusc, which in a certain sense offers a solution to, the conundrum stated by job "Who, hath begotten the drops of dew?"

PROTECTIVE COLORATION

July 17, 1909.

Found a small cowry sh.e.l.l of remarkable beauty on dead coral in the Bay.

At first sight it appeared as a brilliant scarlet boss on the brown coral, and upon touching it the mantle slowly parted and was withdrawn, revealing a sh.e.l.l of lavender in two shades in irregular bands and irregularly dotted with reddish brown spots; the apertures were richly stained with orange, and the whole enamel exceedingly l.u.s.trous. Most of the molluscs of the species conceal themselves under mantles so closely resembling their environments as to often render them invisible. In this case the disguise a.s.sumed similitude to a most conspicuous but common object of anomalous growth, seeming to be a combination of slime and sponge.

CHAPTER XIV

SOME CURIOUS BIVALVES

Though certain species of molluscs have their respective habitats, and that which is considered rare in one part may be common in another, there are few which have not a general interest for the scientific conchologist. Collectors prize sh.e.l.ls on account of their rarity and beauty; the man of science because of the a.s.sistance they afford in the working out of the universal problems of nature. Neither a collector nor a scientific student, my att.i.tude towards marine objects is that of a mere observer--an interested and often wonder-struck observer--so that when I cla.s.sify one species of mollusc as common and another as rare I am judging them in accordance with my own environment and information, not from a general knowledge of one of the most entertaining branches of natural history. From this standpoint I may refer to four or five species which stand out from the rest in interest and comparative rarity.