Hermit-Crabs.
'Finding on the shoar
Som handsome shell, whose native lord of late
Was dispossessed by the doom of Fate,
Therein he enters, and he takes possession
Of th' empty harbour, by the free concession
Of Nature's law--who goods that owner want,
Alwaies allots to the first occupant.'
DU BARTAS.
[Illustration:
1 COMMON HERMIT-CRAB (_Pagurus bernhardus_) in shell of common Whelk
2 COMMON HERMIT-CRAB out of shell
3 SHIP BARNACLES]
V.
Twice in every twenty-four hours the waters of the ocean ebb and flow.
Twice only in each month, however, do the spring-tides occur. For there
are few dangers that the ardent student of nature would not encounter.
Lord Bacon tells of a certain bishop who used to bathe regularly twice
every day, and on being asked why he bathed thus often, answered,
'Because I cannot conveniently bathe _three_ times.' The zoologist,
like the 'right reverend father' alluded to, would willingly undergo
what appears to others much hardship and trouble, not only once or
twice, but even three times daily, in pursuit of his favourite studies,
did Nature but offer the kind convenience.
On these occasions the zoologist can pursue his researches at the
shore, at a distance beyond the usual tidal line. Numerous boulders and
rock-pools, during many days covered by the sea, being then laid bare
and exposed to his eager, searching hands and eyes, he is frequently
able to discover many rare objects, or, at least, common ones
revelling in almost giant-like proportions, and wonderful profusion.
The Soldier or Hermit-Crabs (to an account of whom we intend to devote
this chapter), offer a most remarkable proof of this. Occupying the
centre of a rocky excavation, I have repeatedly found several dozen
of these comical creatures, each inhabiting the cast-off shell of a
defunct Whelk (_Buccinum undatum_), which measured not less than five
or six inches in length. To my surprise these aldermanic crustaceans
possessed no companions of a smaller growth; while at a few yards
nearer shore, as many shells would be found congregated together as in
the more distant pool,--the largest, however, being no bigger than a
damson, while the smallest might be compared to an infantile pea, or
cherry-stone.
I cannot explain this appearance otherwise, than by supposing that
the _Anomoura_ become prouder, or, it may be, more cunning, as they
grow older, and, having arrived at their full development, they
fit themselves with their final suit; thereafter, in a spirit of
aristocratic exclusiveness, they retire to fashionable subaqueous
residences, distant as far as possible from the homes of the
_canaille_, who inhabit the common, littoral boundaries of the shore.
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.
I once possessed a Hermit-Crab, whose voracious movements afforded
considerable amusement to myself and my friends. My Diogenes--or,
as the Cockney news-boys used to pronounce the now extinct comic
periodical, _Dodgenes_--on a certain occasion had climbed up a
segmentally cut frond of Irish Moss. On reaching the topmost point, his
weight became too great for the weed to bear; so, finding he was losing
his equilibrium, in great alarm he made a clutch at the first object
that stood near, in order to save him from falling.
A mussel was moored hard by, to the side of the vase by means of its
silken byssus threads, and upon this friendly bivalve the Pagurus
leaped by aid of his long taper legs. Unluckily the shell of the
Mytilus was open, and the crab unwittingly thrusting his toe within the
aperture, the intruding object was of course instantly gripped by the
mollusc. This accident put him in a terrible fright. His gestures were
most excited, and no wonder. Let the reader fancy himself hanging on
to a window sill, at a height say of twenty feet from the ground, with
the sash-frame fixed on his hand, and a huge iron foot-bath, or some
such object, attached to the lower part of his body, and he will have a
tolerably correct idea of the painful position of our crustacean friend.
After curling and uncurling his tail, and trying several times in vain
to throw his tub upon the valve of the mussel, he released hold of his
encumbrance, and allowed it to drop. Although still hanging, he had no
difficulty in rolling up his 'continuation,' and elevating his body
to the walls of his prison. Once again upon solid ground, he laboured
hard to get his leg free. But unsuccessful in his efforts, he adopted
another course, and snapped it off in a rage.
Scarcely, however, was the act of mutilation finished, when the stupid
animal apparently seemed anxious to recover his lost toe, (which I may
mention, had in reality fallen down among the pebbles).
After scraping, then resting, and scraping again, many successive
times, he at last succeeded in diving the points of his largest claw
into the chasm formed by the gaping mollusc. Of course, the member was
held as if by a powerful vice. Very soon his courage deserted him, and
he seemed to wait and weep despairingly for fate to release him from
the sad predicament into which he had foolishly fallen. Alas! he little
knew the singular part that fickle fortune had doomed him to play,--to
become, if I may so term it, a kind of Prometheus in the tank.
My pack of fishes, having been on short rations for several days, had
become exceedingly ravenous, and consequently were keeping a sharp
look-out for scraps. Hence their intense delight on catching sight
of the devoted 'Dodgenes' can readily be imagined. Such a delicious
_morceau_ was perfectly irresistible:--
'Mercy, mercy!
No pity, no release, no respite, oh!'
At it they went, 'tooth and nail,' First one and then another tore away
a mouthful, until in the twinkling of an eye, almost, the martyr crab
was left forlorn and dead--
'A remnant of his former self.'
During the early portion of last year I had a Hermit-Crab inhabiting a
pretty Purpura, whose shell I wished to sketch as an illustration, it
being of peculiar form and colour. On going to the tank I discovered
that Pagurus had most apropos vacated his turbinated cot, apparently
in consequence of his feeling rather squeamish. Thinking he might
perhaps presently recover, or pick up another dwelling, I hesitated
not to abstract the shell, in order to make the required drawing. I
had not been occupied with my task for more than five minutes, when my
attention was attracted by a great excitement and clatter pervading the
tank. A hasty glance within the vessel sufficed to explain the cause of
the hubbub.
The brief domestic drama of which I was a spectator, with its somewhat
singular denouement, I will now proceed to unfold for the reader's
entertainment. It conveys a good lesson in natural history, and also
exhibits a striking example of life beneath the waters.
The Blennies, I may state, had become very voracious, pugnacious, and
audacious; nothing seemed safe from their attacks. I had begun to feed
them on the _Cardium edule_ and Mussel, but such diet, after a time,
only served to whet their appetite, which certainly appeared to 'grow
by what it fed on,' for they darted about through the water in all
directions, searching, as I suppose, for other dainties. These efforts
were unsuccessful, until they caught sight of the plump, undefended
portion of the body of their companion, the Hermit-Crab, who had just
left his shell, as above stated.
The sight of such a feast must have (figuratively speaking) made their
'mouths water,' One after another these rascally fish dodged round
the crustaceous victim, and gripped, and shook his 'continuation'
with extraordinary violence. In vain did the crab try to act on the
defensive; all his efforts to retaliate were ineffectual, and in this
instance it might be truly said that 'might' overcame 'right.' He ran
to and fro in great distress, scraping the pebbles and shells about
(thus partly creating the clatter that I had heard while sketching), in
the hope that he might find an empty univalve in which to deposit his
mutilated carcase. When almost breathless and exhausted, he discovered
a worn-out Wentletrap, and strove to lift his quivering body into the
aperture, alas! without success. His strength failed him, and he fell
dead at the very threshold of his new-found home.
While watching thus far the above transaction, the writer felt almost
inclined to waver in the faith he had long held with others, namely,
that fishes and other marine animals are insensible to pain. But
the movements of this poor Hermit-Crab were as indicative of severe
suffering as anything he ever witnessed in bird or quadruped.
Wishing to examine the remains of the crab, I stepped aside for a few
moments to procure my forceps, but when I again reached the vase, to
my intense surprise the defunct animal was nowhere to be seen! I could
only account for so singular a circumstance by supposing some of the
larger crustaceans had taken advantage of my absence to complete the
work of destruction, and therefore took no further notice of the matter
at the time.
I had often wished that some of my finny pets would deposit their spawn
in the tank, and felt very anxious, if such an event did take place,
that I might be near to witness it. But I was most anxious to watch the
gradual development of the ova, and, if practicable, to become the fond
owner of a host of infant 'fishlings.'
Guess the thrill of pride, then, which ran through my veins when, on
peering into my mimic rock-pool, after a brief absence from home, I
observed the largest of my Blennies to be apparently in an 'interesting
condition.' I watched and petted her many times daily, and fed her with
every suitable dainty that could be thought of. Sometimes I took her
in the palm of my hand, and with a fine camel-hair pencil stroked her
glossy back. This operation evidently gave great delight to the little
beauty; and after a while, when my hand was laid in the water, she
gently floated off into her native element with almost swan-like grace.
The law of nature being the same with this fish as with the
Stickleback, I knew the nest, if there was to be one at all, should
be built by the male. But as I could not detect any specimen of the
'sterner sex' among my pack, and there being no signs of preparation
for the grand event about to take place, I felt in a manner compelled
to carry out the nidifying task in my own humble way. Of course, I gave
up all idea of 'weaving' a nest with bits of weed, stones, and marine
glue; nor was such a style of structure a desideratum in the present
instance, wanting, as I did, to take notes, in Paul Pry fashion, of the
minutest particular that might occur within the building. The following
was the plan I adopted. First was procured the exquisitely formed valve
of a large _Pecten_, the interior of which was white and beautifully
irridescent. This pretty cot, I said to myself, shall serve as a
chamber for my _protégé_. The shell being deposited behind a piece of
rock, in such a position that its side rested against the surface of
the glass, I was thus enabled to watch what was going on within. Some
fronds of sea-weed were trained around so as to form a kind of drapery.
The Blenny, I am quite certain, knew perfectly well that all this care
and preparation was on her account, for nearly the whole of each day
she spent in the novel apartment extemporized for her accommodation.
After a week had elapsed, she grew uneasy and pettish, was ever
snapping at her companions, and hunting them about in all directions.
On one occasion, however, she seemed to be uneasy, now clashing round
the rock, then darting to the top of the tank, and down again upon the
pebbles. Scores of times these movements were repeated, until I felt
alarmed for her safety, and annoyed at my inability to relieve her
sufferings. But aid from me being impossible, I felt compelled, though
very unwillingly, to allow nature to take its course.
On looking into the aquarium one morning, I observed some strange
object protruding from the fish. The little creature, too, on catching
sight of me, came to the side of the tank, near to where I stood, and
by her movements asked me, as plainly as any dumb animal could ask, to
give her my assistance. After a few minutes spent in a 'brown study', I
resolved to grant her petition, and immediately setting to work, drew
from her--what? what do you suppose, reader? In truth neither more nor
less than the body, head, and long antennæ of the 'martyr' Hermit-Crab!
whose late sudden disappearance was now fully accounted for.
There are ten British species of Lobster-Crab, but one only, _P.
Bernardhus_, to which the reader has been introduced, is common to our
shores.