The Crab and the Dainty Beggar.
'In taking a review of most, if not all the actions of the animal
world, it must be obvious that, whether we allow them reason or not,
the actions themselves comprehend those elements of reason, so to
speak, which we commonly refer to rational beings, so that if the same
actions had been done by our fellow-creatures, we should have ascribed
them without hesitation to motives and feelings worthy of a rational
nature.'--SCHLEIDER.
'All things are bigge with jest; nothing that's plain
But may be wittie, if thou hast the vein.'
--GEORGE HERBERT.
XV.
I have been observing for several days the movements of a Common
Shore-Crab, which has been almost all his life under my protection.
Although his present dimensions would render such a feat impossible,
when first I shook the little fellow off a bunch of _C. officinalis_,
he could have crawled with the greatest of ease into the mouth of a
small popgun. We all know that members of this family are bold and
daring in their attacks upon their weaker neighbours; upon each and all
they wage a constant predatory warfare. The poor Pholades, however, are
the favourite objects of their attacks. On these innocent bivalves the
Crustacea successfully prey, unless they are protected by their usual
rock-bound citadel, which, of course, they cannot always be. In order
to watch the Pholas at work, it is necessary that the siphons should be
more or less protruding from his tubular dwelling. If supported, say,
to the full depth of his valves, the animal is secure; for I notice
that neither crab nor fish can tear away the gristly ends of the
siphonal appendages when withdrawn; and when disturbed, the poor Pholas
leaves only this part in view. I have frequently seen the Fiddler-Crab
embrace a Pholas in his claws, and struggle to pull him from his seat.
On one occasion this operation was performed successfully, much to my
annoyance, as I had been at some trouble to saw the rock away in order
to watch easily every movement of the animal within. At night when I
looked into the tank my pet was safe; next morning it was wedged under
some pebbles, and the crab was feasting leisurely upon his tender flesh.
It is most amusing to watch the Blennies, too, attack a Pholas, cast
into the tank, and to witness their mode of pecking at and shaking
their victim, and turning innumerable somersaults with it in their
mouths. The strength they exhibit in these manœuvres is perfectly
astounding.
About two hours after they had received one of their favourite
'muttons' to feast upon, I peeped into the aquarium, and found, as I
expected, the Blennies hard at their work of destruction. Behind them,
among some bushy tufts of _I. edulis_, the little crab, before alluded
to, was seated. In his arms he held an object unlike anything I had
seen on sea or land. It appeared like a slender stick of beautifully
iridescent opal. My amazement at this sight may readily be conceived,
for I had not the remotest idea as to how he had become possessed of
such a prize.
Next day I placed another devoted Pholas in the tank, and after a while
looked in to see how its finny enemies were conducting themselves,
when, what should meet my eye, but the crab, sneaking off with another
opal baton in his arms! I was more puzzled than ever. It was quite
certain that the object in question had been procured from the Pholas,
yet I had not heard of, or ever seen anything like it in that animal.
I was 'on thorns' until next day, so that I might by watching solve
the mystery. A third Pholas was flung into the den. The fishes, eager
as usual, instantly attacked and pulled the mollusc to pieces. After a
while the crab began to move about to and fro, evidently very restless,
and anxious for my departure. I did retire, but only to such distance
as would allow me a distinct view of his movements. In a few moments he
stepped out mincingly on the tips of his toes, and crossed the tank to
the spot where the poor Pholas lay, like some fine beau in Queen Anne's
reign tripping jauntily down the Mall, or across St. James' Park, to
feed the ducks in Rosamond's Pond.
The Blennies darted off at his approach. He then seated himself before
the mangled corpse, and scraped at it vigorously, manifestly searching
for some coveted treasure. Shortly after, perceiving him clutch at
something, I quickly approached and disturbed his movements--took up
the Pholas, and to my surprise found, on drawing out an object that
protruded from the foot of the animal, that I possessed the pearly and
gelatinous cylinder, such as the crab had twice before devoured with
such evident relish.[11]
[11] My first introduction to the Hyaline stylet as above narrated,
occurred in October 1858.
It was plain then that the little rascal had become so dainty, that
he 'turned up his nose,' or rather his 'pair of noses,' at what is
vulgarly termed the 'first cut,' and condescended only upon the
tit-bits, for his marine banquet. So his crabship, in order to save
himself trouble, actually waited until the fishes had cut up the
Pholas to a certain point, when he would rush forward and seize on his
favourite fare.
Some of my readers will doubtless remember the anecdote of the crossing
sweeper, whose idiosyncrasy led him to covet diurnally a mutton-chop
situated in the middle of the loin. My Lady Pepys, or Mr. Saccharine,
the great grocer, couldn't always procure the desired 'cut!'
_n'importe_ the knight of the besom met with no such disappointment.
This individual's place of business was luckily situated opposite to a
noted butcher's shop, which circumstance easily enabled him to watch
until, from the demands of sundry customers, the perspective of the
loin, which lay temptingly upon the chopping block, had become adapted
to his point of sight. He would then step in and meekly order a simple
pound avoirdupois. With this _bonne-bouche_ carefully packed in his
pocket, he would again mount guard, and remain until night. At dusk of
evening he shut up shop,--that is, he swept the dirt over the parallel
path that he had all day kept scrupulously clean, and then marched off
to enjoy his dinner at a fashionable hour, in private.
Are not these cases palpably alike? Passing by certain details, were
not the pawkiness and cunning of the epicurean beggar fully equalled by
our diminutive friend, _C. mænas_?
'But,' you ask, 'what then was the opal stick?' Ay, there's the rub,
for even the greatest naturalists cannot positively agree as to the
use and purpose of this mysterious organ. Yet it is to be found (as we
have seen) in the foot of the Pholas, in the Mussel, the Cockle; and,
in fact, it occurs in almost all bivalves both great and small. It is
termed the 'hyaline cylindrical stylet,' and is very _lucidly_ and
scientifically described as 'an elastic spring to work the corneous
plate or attritor, and by the muscular action of the foot and body, to
divide and comminute the food, and especially the minute crustaceous
and testaceous alimentary matters received into the stomachial cavity.
It appears then that this appendage acts as _a gizzard_, and the
bivalve mollusca are thus supplied with a masticatory apparatus very
analogous to the gizzards of some of the gasteropoda.'
Now, the simple fact that I have stated above, of the hyaline stylet
being found in the _foot_, and not in the stomach, at once proves
that it cannot possibly act as a _gizzard_ to the Pholas, or any other
bivalve in which it is known to exist.
In the succeeding chapter I shall endeavour, from personal observation,
to shed a slender ray of light upon the function of the stylet.