Part 3

Then we have the soft-tailed, _Soldier_, or _Hermit Crabs_, who, because they are insufficiently clad by nature, seize on the first convenient shell they can discover, and then, by adroitly introducing the point of the tail, slip into it, much as a skilful stage demon vanishes through a _vampire trap_. Vacant shells are not always selected as mansions; those with inhabitants are not unfrequently taken possession of, when a process of forcible ejectment is had recourse to, and the hapless mollusc is soon gobbled up, and his house occupied by the spoiler. _Pagurus Bernhardus_, the subject of the annexed illustration, is no doubt familiar to many of our readers, as most of the little salt-water ponds amongst the rocks and stones have one or more of these tiny hermitages in them. Whelk-shells are very commonly found inhabited by the pagurus we are describing, and large numbers, under the name of _Crab Whelks_, are collected, and used as bait, after the shell and hard structures have been removed by breaking them off with a hammer.

_Pea Crabs_ there are also, living at free quarters in houses not their own; but of these we shall have more to say further on. The Hermits we find on our coasts are perfect pigmies when compared with some of the species found in and about the tropic seas, who, dwelling in the huge helmet-like shells with which these warm regions abound, spend almost as much of their lives out of the sea as in it, consume large quantities of vegetable matter, and appear capable of supporting life for some time without absolutely going into the water.

Tenantless mollusc shells are not the only dwelling places of the Hermits, and other species of Crabs, and they have, from periods of remote antiquity to our own day, been found in situations in which they apparently have no reasonable right to be. This has given rise to much learned disputation, and not a few wild theories and quaint conceits.

That matchless piece of nature’s handiwork, the Philippine Island sponge (see next page)--Venus’s Flower Basket, or _Euplectella speciosa_, of naturalists--which has recently attracted so much attention in the British Museum and among the scientific world, was, about a year since, accidentally hauled up from the bottom of the sea, entangled on a fish-hook, by a native who was fishing for rock cod off the Island of Zebu, one of the Philippine group. Since the first discovery, numerous specimens have been obtained in the same locality, and from 30_l._ (the price paid for the fisherman’s prize) the value has progressively become less. Still purchasers are numerous enough to make flower-basket hunting a remunerative occupation for some time to come. It is perfectly impossible, even with the aid of pictorial illustration, to give an adequate idea of the elegance and beauty of this extraordinary production. Of cornucopiæ form, and of the finest Brussels lace texture, it stands like a network vase among a tuft of crystal threads. The cover, like that of some antique flagon, crowns the top, and completes the strange resemblance to man’s most skilled and perfect productions. Venus herself might well be proud of such a flower-basket; but like many other things of beauty, there are mysteries round their growth and formation. One of these, is the almost invariable presence of the remains of one or more Crabs in the interior of this, to them, crystal prison, out of which escape is just as impossible as from a capsuled bottle. Many differences of opinion exist as to the mode by which the Crabs first obtained an entrance; there appears, however, little doubt that this is effected whilst the sponge is in an immature condition, and before the cover is woven. There is a young specimen which we have examined in the British Museum in this incomplete state, and it is questionable whether the basket-like tube is ever covered until it has reached maturity; when, although the sponge appears to cease growing in an upward direction, the power possessed by it to secrete the silicious matter of which the network is composed remains unimpaired, and, like a skilful artisan as he is, he at once repairs neatly such injuries as his crystal palace may sustain.

Dr. Gray has in his possession a specimen in which a repair of this kind has been effected. A hole appears to have been broken by some accident in one of the sides about half-way between the point of attachment and the cover. A new network of fibres in bunches has been substituted for the broken ones--of form much like the original structure. The peculiar curved or _cornucopia_ shape before referred to, and usually, although not invariably, assumed by these baskets, has also given rise to much speculation amongst the scientific. Dr. Gray gives it as his opinion that the weight of the Crab when crawling through the interior of the tube, may influence the direction in which the basket is found to incline. He says: “As the Crab becomes imprisoned in the cavity, it will be constantly walking up and down the tube to procure food, and by so doing will, most likely, bend the tube on one side, so that the free end of the tube may become bent down nearly to the level of the base;” and it remains an open question whether this is the true solution of the enigma, or, like the goblet forms of some species of sponges, and the rounded contour of others, the cornucopia form of growth may not, after all, be that common to _E. speciosa_.

It appears to be the prevailing opinion amongst the fishermen by whom the Euplectella is taken, and by whom it is known as the _Rigederos_, “that it is the work of two insects (meaning probably the Crabs found in the tubes) at the bottom of the sea.” A French correspondent in writing recently to the authorities of the British Museum, expresses his opinion that the Euplectella is the work of the Crabs. There are very grave reasons, however, why this opinion should be received with the greatest caution, if not absolute doubt. In the first place, we know of no crustacean possessing a like power of silicious secretion and construction. Then the Crabs which are found inclosed are not always of the same species, or even genera. Dr. Gray is of opinion that one which he examined through the meshes was a _Pagurus_, and of habits identical with those which we have already described. Crabs with such investigating and intrusive instincts as these, would not fail to explore the inmost recesses of a hollow tube of such a tempting appearance as the young, growing, and coverless Euplectella would present; and what more probable than that, as the tube became perfected and the lid partly made, the Crab or Crabs might still continue to inhabit it, until the orifice being at last closed up, and escape impossible, our friend remained a prisoner for life. His cast-off shells, like old worn-out garments, would remain sealed up securely with him, and give the idea that many Crabs had there resided.

The ancients, although totally ignorant of the existence of the beautiful lace-work basket we have described, and the creatures dwelling within them, were nevertheless perfectly aware of the presence of small Crabs in the shells of the great silk-yielding mussel (_Pinna nobilis_), who, because he had no visual organs himself, was supposed to need the services of a vigilant submarine watchman, sharp of ear and keen of eye--a sort of _concierge_, in fact--to attend to the door and keep out all unwelcome visitors.

The researches of Lamarck go to show that the ancient writers were generally of opinion that these Crabs were especially employed as general guardians and inseparable companions to the Pinna, that they had one common birth, and that the one could not exist without the other,--the absence of vision in the Pinna being compensated for by the vigilance of the Crab, whilst in matters requiring power and resistance, _Cancer_ had only to give the required sign by a gentle nip, when his partner, with the strength of a sea-giant, shut his shell-trap-door on all the inquisitive, intrusive little fish within the fatal portal, when the firm of _Pinna_ and _Crab_ made remarkably short reckonings with them. We read that in 1749, Hasselquist, the distinguished naturalist, undertook a voyage to the Levant, and corresponded with Linnæus during his travels. In one of his communications he thus writes from Smyrna:--“Amongst others they sell here a _sepia_, or cuttle-fish, which by them is called Οκτωποδια. It has only eight tentacles all of equal length. The whole animal is a foot long, and thick in proportion. Of this the Greeks have related an anecdote which I think remarkable. The _Pinna muricata_, or great silk mussel, is here found in the bottom of the sea in large quantities, and is a foot long. The cuttle-fish watches the opportunity when the mussel opens her shell to creep in and devour her; but a little Crab which has scarcely any shell, or has at least only a very thin one, lodges constantly in this shell-fish. She pays a good rent by saving the life of her landlady, for she keeps a constant look-out through the aperture of the shell, and on seeing the enemy approach she begins to stir, when the πινα (for so the Greeks call the shell-fish) shuts up her house, and the rapacious animal is excluded. I saw this shell-fish first at the Island of Milo, and found such a little Crab in all I opened. I wondered not a little what was her business there; but when I came here, I was first informed of it by the Secretary of our Consul, M. Justi, a curious and ingenious man, who has travelled much, and lived long in this place. This was afterwards confirmed by several Greeks who daily catch and eat both these animals.”

The common Pea Crab (_Pinnotheres pisum_), represented in the annexed cut, and of enlarged scale, is an inhabitant of our own coasts, and frequently found residing within the shell of the common edible mussel, (_Mytilus edulis_); but it is very remarkable that the female Crabs are very much more numerous than the males, and that although the male Crab may be at times captured at a distance from his strange lodging, we know of no instance of a female being taken in any situation but within the shell of some mollusc. Aristotle speaks of this small mail-clad janitor as a little fish with claws, like those of a Crab, which keeps guard and ward for the _Pinna_, grows to her mouth, and acts as her caterer. Pliny too remarked and described the apparently anomalous association. He speaks of the Pinna as a shell-fish that is found in muddy waters, always erect, and never without a companion of the Crab kind. Oppiannus not only knew that Crabs existed commonly in the Pinna shells, but clearly conceived that it was their duty and mission to do so. Thus he writes:--

“The Pinna and the Crab together dwell For mutual succour in one common shell; They both to gain a livelihood combine,-- _That_ takes the prey when _this_ has given the sign. From hence this Crab above his fellows famed By ancient Greeks was _Pinnatores_ named.”

The accompanying illustration, on a very enlarged scale, represents the pinna’s companion, _Pinnotheres veterum_, which will be seen at a glance to differ materially in appearance from _P. pisum_. The mussel is not the only shell in which _P. pisum_ finds ready-furnished lodgings. The common cockle (_Cardium edule_), and in some instances the ordinary oyster, being selected to supply them. Mr. W. Thompson, in writing on the crustaceans of Ireland, says, “The smallest Pinnotheres I have seen was found by Mr. Hyndman, in a living _Cardium exignum_, dredged up by us in Strangford Lough, in October, 1834. It is a male. The carapace is under a line in length; the entire breadth of the Crab from the extremities of the outstretched legs is three lines. The cardium is under three lines in length, and barely exceeds that admeasurement in breadth; so that the Crab, when in the position just mentioned, must have on both sides touched the walls of his chosen prison. The _Pinnotheres_ likewise inhabits the _Cardium edule_. Before me is one of these Crabs, of which the carapace is two lines in breadth, obtained by Mr. Hyndman in a full-grown _C. edule_ from Strangford Lough; but from the Sligo coast where this Crab attains an extraordinary large size, a Crab with a carapace four lines in breadth, and with outstretched legs seven lines across, was once kindly brought to me by Lord Enniskillen. Mr. R. Ball informs me that on two occasions he obtained a great number of the Pinnotheres, and which were all males, from the _Cardium edule_, when at Youghal. About nine out of every ten cockles contained a Crab. On opening oysters at Tenby in Wales he has procured the Pinnotheres. This Crab, like the _Pagurus_, occupies different species of shells according to its size, and at every age, and generally selects such as with outstretched legs it would fill from side to side.”

Another extraordinary instance of anomalous association is to be found in the habits of the _Pagurus prideauxii_, which is invariably found with the cloak Anemone (_Adamsia palliata_) adhering to it, and so strong are the mysterious bonds of relationship, friendship, or whatever it may be called, which bind them together, that on the Pagurus finding it requisite to increase the size of his borrowed mansion, the Anemone, like a chosen companion as he is, follows to the new home, being deftly held by the nippers of the fresh inhabitant until enabled to obtain a firm hold just outside the portal, where it remains until some other removal is made, or more commodious quarters required. From these sociable house-hunting adventurers we pass on to the burrowing Crabs, of which there are many kinds, indulging in habits most curious and noteworthy. Perhaps the most remarkable of these, is the great Cocoa-nut Eating Crab, or “_Ou-Ou_,” as it is called by the natives of some of the localities in which it is met with. It is the _Birgus latro_ of naturalists, and is well represented, although on a very reduced scale in the illustration next page. It is found in many of the Coral Islands dotting the Indian seas and Pacific ocean, and beneath the rustling, waving, cocoa-nut groves, which abound within the torid zone. The _Ou-Ou_ forms for himself a home, delving and burrowing, miner-like, beneath the wide-spreading roots of the tropic trees, and excavating deep and cunningly-formed galleries and chambers in the coral sand and broken shells; and one is almost disposed to think that the following lines by Thomson must have been penned in all the fervour of a poet’s admiration for the happy lot of our friend of subterranean proclivities:--

“Sheltered amid the orchards of the sun, Where high palmettos lift their graceful shade, Give me to drain the cocoa’s milky bowl, And from the palm to drain its fresh’ning wine, More bounteous far than all the frantic juice Which Bacchus pours.”

Here, like a feudal baron of old, he forms for himself a stronghold, sallying forth like a freebooter, to feast on the spoils of the grove. Curious stories are related of these marauders, and it has been gravely asserted that they have been known to ascend the tall stalks of the cocoa palms for the purpose of detaching and throwing down the nuts. We are not prepared to say that particular palms (when in a more than ordinarily sloping posture) may not been have climbed in the manner stated by certain species. Our own experience, however, strongly disposes us to think that such nuts as from time to time fall to the ground from ordinary causes, constitute the prizes commonly appropriated by _B. latro_. His enormously powerful and ponderous nippers enable him to husk and rend these from their tenacious coatings with surprising speed and facility; and it is only necessary to examine the cocoa-nut husks with the nuts within them, as imported from abroad, to be convinced that our nut-eating friend must be a veritable crustacean Hercules, to be capable of such feats of strength, as the dragging forth of the treasures from their dense fibrous envelopes unquestionably are; and a Hercules he is in his own way, for the tenacious wire-like network of cocoa fibre in which the nut is inclosed, is torn, split, and rent asunder, as though with the iron pincers of a brawny blacksmith, until the coveted dainty is set free. One end of every common cocoa-nut has, as most of our readers are aware, three holes in it; these, from their position and quaint resemblance to the face of a living creature, are called the monkey’s face. One of these holes is selected as a point of attack, and a succession of adroitly-delivered and heavy raps are rapidly given with the large claw. An opening, or breach, is thus very quickly effected. The narrow pair of nippers now come into operation, and by dexterously inserting them, the whole of the white, sweet, oleaginous contents are deftly scooped and clawed out. _B. latro_ has a keen eye to future wants as well as to present enjoyment; he is not only a gourmand, but pretty much of a utilitarian; so he employs his sharp, powerful claws in carding and combing up the bundles of tangled coir, remaining after his husk-splitting operation. This, by dint of much clawing to and fro, at length becomes almost as fine as tow, or the oakum used by shipwrights. When sufficiently manipulated, he gathers together the result of his labours, and transports it to the inmost recesses of his subterranean stronghold beneath the roots; a bed is here made from it, on which our friend reclines; and it helps to form a convenient covering and protection for him when debarred from the pleasures and delights of Crab society during the uncomfortable process of shell-changing. The crafty human inhabitants of these wave-washed isles, are too well versed in the habits of our friend, and too well aware of his provident habits, not to avail themselves of the stores of well-preserved fibre thus laid up; advantage is therefore taken of the buried store, which is unceremoniously dragged forth, collected together, and made use of for caulking the seams of their canoes, and many other useful purposes. During the period of comparative torpidity usually accompanying the shell-shifting process, the wants of nature are wonderfully and wisely provided for. These strange creatures are each furnished with a species of natural magazine, containing fatty matter, which they carry beneath their tails. Some Crabs of large size have been known to yield enough to produce a quart of oil, limpid, of excellent quality, and highly esteemed by the natives. _B. latro_ is much given to nocturnal rambling, and frequent visits are by him paid to localities within the cheering influences of the salt-sea wave; but we do not agree with those writers who have accused him of nightly hydropathic journeys. During the breeding season some considerable time is spent by the whole family in exploring the countless rock-pools and lagunes between the coral reefs. Here, after the departure of the parents for their homes amongst the roots, the juvenile crabs continue to desport themselves, until grown strong enough to attack the nuts on their own account, when they proceed to join their seniors in the family diggings. The natives, when they set their minds on a Crab-hunting expedition, provide themselves with much the same kind of equipment as a party of English gamekeepers would use when about to extract a secretive badger from his burrow. Digging, and that of the most determined and energetic description, is the favourite method of bringing the game to light, which desirable consummation is rarely arrived at until a very large amount of loud shouting and needless leaping about has been had recourse to. The unfortunate Crabs are very good to eat, and they appear thoroughly aware of it, making use of every effort in their power to avoid capture. They are, nevertheless, ruthlessly overtaken in the subterranean race, dragged forth into the broad sunlight, ignominiously bound with cords twisted from the tough fibre of the cocoa husk (a very requisite precaution by the bye), and lugged off into hopeless captivity.

Some of these nut-feeders grow to a monstrous size (some being over two feet long), are armed with nippers of most formidable dimensions, and make no more of snapping the strong cord, with which the Crab-catchers endeavour to secure them, than if they were as many strands of packthread. At certain seasons of the year a vegetable diet appears to become unpalatable to our friend. He then seeks a change, and levies open and indiscriminate warfare on all the tribe of shell-bearing molluscs he can lay his thievish claws on, not giving even the ghost of a chance of escape. He seizes them forcibly with his nippers, and then extracts them from their snug shell-castles, with a dexterity which an accomplished London shell-fish dealer might look on with envy; and then, not content with devouring the ill-fated tenant, he performs a sort of grotesque defiant, and triumphal march, with the vacant shell raised like a standard, aloft in his claws, as if for the express purpose of inciting other Crabs more peaceably disposed and less nefarious in their habits, to the perpetration of outrages of a similar character. Take him for all in all, _B. latro_ may be considered anything but a well-conducted member of the family to which he belongs. His name denotes the character which he has fully earned and universally maintains.