Glimpses of Ocean Life 11

Glimpses of Ocean Life 11

The peculiarity, to which I alluded, of the _Anomoura_ occupying

shells that have formerly belonged to other animals, is so strange

that some writers have not hesitated to express doubt upon the

subject. This denial of a fact, which can so readily be proved, is one

of the 'curiosities of literature.' Swammerdam, a Dutch naturalist

contemptuously observes, 'What an idle fable that is which is

established even among those who study shell-fishes, when they show

some kind of the crab kind in their museums, adding at the same time,

that they pass from one shell to another, devour the animals that

lived in those shells, and keep them for their own habitations. They

dignify them with the high-sounding names, and additions, as Soldiers,

Hermits, and the like; and thus, having no experience, they commit

gross errors, and deceive themselves, as well as others, with their

idle imaginations.'

 

That there is nothing mythical in the matter can easily be made

apparent to any person who chooses to visit the sea-shore. At such

locality he need have no difficulty in recognising the Hermit-Crab, or

meeting with numerous specimens for examination. Supposing such a one

is at a rock-pool, and, moreover, that he knows by sight the Buckie

(periwinkle), and Common Whelk, he will probably in such case be aware

that the animals occupying these shells are snail-like in construction,

and that their locomotion is consequently slow and formal. If,

therefore, when peering into any pool he sees the Buckie, for instance,

apparently change its nature, and instead of

 

'Dragging its slow length along,'

 

scamper off suddenly, or roll over and over from the top of an

eminence to the bottom, he may rest assured that the original

inhabitant has departed, and that its place is occupied by a

Lobster-Crab.

 

The cause of his strange peculiarity I will briefly explain.

 

In the true Lobster the tail forms a most valuable appendage. In the

tail the principal muscular power of the animal is seated; and by means

of it, too, the animal is enabled to spring to a considerable distance,

and also to swim through the water at will. This important organ is

well protected by a casing consisting of a 'series of calcareous rings,

forming a hard and insensible chain armour.'

 

In the Lobster-Crab there is no such arrangement. 'The abdominal

segment of this singular animal, instead of possessing the same

crustaceous covering as the rest of his body and claws, is quite

soft, _and merely enveloped in a thin skin_. To protect this delicate

member from the attacks of his voracious companions, the poor Pagurus

is compelled to hunt about for some Univalve, such as a Whelk or

Trochus, and having found this, he drops his tail within the aperture

and hooks it firmly to the columella of the shell. Why Providence

has doomed the poor Hermits to descend to such physical hypocrisy,

and clothe themselves in the left-off garments of other animals, it

is not easy to conjecture. No doubt, besides the defence of their

otherwise unprotected bodies, he has some other object of importance

in view. Perhaps they may accelerate the decomposition of the shells

they inhabit, and cause them sooner to give way to the action of the

atmosphere; and as all exuviæ may be termed nuisances and deformities,

giving to these deserted mansions an appearance of renewed life and

locomotion, removes them in some sort from the catalogue of blemishes.'

 

Professor Jones, when treating of this class of animals, forcibly

remarks that 'the wonderful adaptation of all the limbs to a residence

in such a dwelling, cannot fail to strike the most curious observer.

The _Chelæ_, or large claws, differ remarkably in size, so that when

the animal retires into its concealment, the smaller one may be

entirely withdrawn, while the larger closes and guards the orifice. The

two succeeding pairs of legs, unlike those of the Lobster, are of great

size and strength, and instead of being terminated by pincers, end in

strong-pointed levers, whereby the animal can not only crawl, but drag

after it, its heavy habitation. Behind these locomotive legs are two

feeble pairs, barely strong enough to enable the Soldier-Crab to shift

his position in the shell he has chosen; and the false feet attached

to the abdomen are even still more rudimentary in their development.

But the most singularly altered portion of the skeleton is the fin

of the tail, which here becomes transformed into a kind of holding

apparatus by which the creature retains a firm grasp of the bottom of

his residence.'

 

So great is the power of the animals to retain hold of their shell, and

so intense their dislike to be forcibly ejected therefrom, that they

will often allow their bodies to be pulled asunder, and sacrifice their

life rather than submit to such indignity. This fact I have proved

on sundry occasions. But supposing a crab to have taken a fancy to a

shell, occupied by some brother Pagurus, (a circumstance of frequent

occurrence), he quickly proceeds to dislodge the latter. Curious to

state, this process never seems attended with any fatal result.

 

When watching the operation, it has appeared to me as if the crab

attacked preferred to yield rather than be subjected to continuous

annoyance, and the discomfort of keeping for so long a time buried

within the inner recesses of his dwelling.

 

The contrast in appearance of the Hermit-Crab when seated in his shell,

and crawling about minus such appendage, is great indeed.

 

This the reader will readily perceive by examining the Illustrations on

Plate 4, which are drawn from nature, and are truthful portraitures of

this singular creature.

 

I have already mentioned the extreme difficulty there is in expelling

a Lobster-Crab. This, be it understood, applies only to the animal in

good health; for no sooner does he feel sick than he instantly leaves

his shell, and crawls about in a most pitiable plight. He sometimes

becomes convalescent again by being placed solus in some fresh water,

or laid out in the air for a few moments. But he ought, on no account,

when in a sickly condition, to be allowed to hide himself beneath any

pieces of rock or shadow of the Algæ.

 

If he is out of sight, be sure not to let him be out of mind; for,

should he die in the tank, and his body be allowed to remain for any

length of time, he will very soon afford you full proof that such

toleration on your part is anything but pleasant.

 

Although, as already stated, this animal cannot be drawn out of his

shell except by extreme force, the object can easily be obtained by aid

of strategy. Having been for some time at a loss how to give certain

young visitors a sight of the Hermit-Crab in his defenceless state, I,

by accident, hit upon the following simple plan:--

 

With a piece of bent whalebone I lifted up a Pagurus, shell and all,

and allowed the latter to drop upon the outer row of the tentacula of

an Actinia, which quickly stuck fast to the intruding object. The crab

at first did not seem fully alive to his critical position. He popped

out of his shell and looked unsuspectingly around, until catching

sight of my face, he instantly retired from view with a casket-like

snap. In a minute he was out again, and this time prepared to change

his position. For this purpose he gave several successive pulls, but

finding all his efforts to remove his carriage unavailing, he unhooked

his tail and scrambled down among the pebbles. My purpose was thereby

gained, for the next moment he was resting in the palm of one of my

juvenile friends, who seemed quite delighted with his prize. Twice

afterwards, being in a mischievous mood, I gave the crab a fright in

the way just mentioned; but it was quite evident, that what might be

sport to me was death to him, for he was both annoyed and alarmed at

my procedure. Even when guiltless of any intention of touching the

creature, if I merely showed him the cane he immediately hobbled away

at the utmost rate of speed he could muster. On several occasions I

followed after and brought him back to the edge of the tank, although

such conduct met with his strongest disapproval, and caused him for

some time to sulk beneath an arch-way of rock work, away from the reach

of vulgar eyes.

 

Upon the side and near the base of my tank a fine specimen of the

Limpet was at one time attached. From the centre of its shell a forest

of sea-grass waved gracefully, shadowing a large colony of Barnacles

thickly clustered beneath. Soon the Patella decided upon taking its

usual morning stroll in search of food, a task of little difficulty,

standing as the animal already did upon the margin of a broad meadow,

richly coated with a verdant growth, composed of the infant spores of

the Ulva. Slowly moving along, the Patella, with its riband-like band

of teeth, swept off the luscious weed in a series of graceful curves,

thus making an abundant and healthful meal. Before proceeding far,

however, he was forced to bear the weight of a Soldier-Crab, who had

most unceremoniously climbed upon his back, and taken up a position at

the base of the _latissima_ fronds.

 

There seemed so much nonchalance about the Pagurus that I determined

to watch his movements, and, if possible, to see how he would manage

to descend from a position which, if the mollusc continued his mowing

operations, would soon be unenviably high.

 

In about an hour the Limpet had reached the level of the water in the

aquarium, and there took up his abode for the night. Next day and the

next there was no change of situation. The crab now began evidently

to perceive the danger of the position in which he was placed, for he

constantly moved to and fro, and peered over into what must have seemed

to him an unfathomable abyss.

 

While I stood, the Patella made a sudden movement of its shell--so

sudden, indeed, as to startle its companion, who quickly put out his

claws to save himself from falling. Unfortunately, in his spasmodic

gesture he allowed the tip of one of his claws to intrude under the

edge of the conical canopy, thus, in fact, pricking the fleshy 'mantle'

of the animal within, who instantly, of course, glued itself to the

glass with immoveable firmness. I suppose the same thing must have

frequently occurred without my knowledge, for after a lapse of several

days the Pagurus and his bearer were still in the same spot. I felt a

growing alarm for the continued health of the Hermit-Crab, from the

fact of its being poised so directly over the ever-expanded tentacles

of a large Anemone. To prevent any mishap, I went to lift his crabship,

with a view of transferring him to a place of safety, when, no sooner

did he perceive the advancing forceps, than he rushed into his shell

with a sudden and audible 'click,' forgetting for the moment that he

stood on such ticklish ground. The consequence was that, seeking to

avoid Scylla, he fell into Charybdis. In other words, he dropped plump

upon the well-gummed tenter-hooks of the Crassicornis, which instantly

closed and engulphed its prize. In vain did I endeavour with all speed

to pick out the devoted Pagurus. The more I tried, the more firmly did

the Actinia hold him in its convulsive grasp.

 

With extremely few exceptions, the Hermit-Crabs are always found to be

a prying, prowling, curious class of animals, and are ever, like the

husband of the fair Lady Jane--

 

'Poking their nose (?) into this thing and that.'

 

They will turn over each shell and pebble that comes in their way, and

examine it with profound attention, or industriously climb up and roll

down hillocks and trees in the shape of small rocks and sea-weeds, much to their danger.