Prawns and Shrimps.
'Men holden ye therefore prophanes
Ye eaten neither shrimps nor pranes,'
VII.
Although abundant at many parts of the Scottish coast, at Cockburnspath
(situated near the mouth of the Frith of Forth) only, has the writer
met with the very beautiful prawn, _Palæmon Squilla_. At this locality
specimens were very frequent in rock-pools situated near the shore, nor
were such difficult to capture. The small net being placed cautiously
over their head, the animals did not show signs of resistance, until
they found themselves, by a sudden jerk of the hand, drawn bodily out
of the water. Then, indeed, unless some degree of skill was used, the
captives would give a powerful spring, and escape, from the confinement
of the net, to the more congenial element from which they had been so
unceremoniously ejected.
Prawns (_Palæmonidæ_) exuviate very frequently, in some instances as
often as once or twice a month. No sooner is one coat thrown off and
the Palæmon recovered from the weakness which the process occasions,
than it commences, at first at intervals, and then almost incessantly
day and night, preparations for a renewal of the wonderful operation.
Every part of the body--eyes, antennæ, and especially the sub-abdominal
fins, to certain portions of which the ova are attached in groups,
and the lobes of the tail--are submitted to a severe rubbing and
brushing process. The appearance of the prawn at this period is
really most interesting, and, I may also add, amusing. Sometimes the
tail is compressed inwards, beneath the body for a few seconds, and
then suddenly elevated and forced out with donkey-like extravagance
of gesture, the animal the while standing upon its first pair of
forcep-like feet.
At the appointed time the shell opens at the back part of the head,
and the prawn becomes gradually freed from its old covering. The
marvellous process completed, like all its crustaceous brethren, the
creature becomes to a certain extent helpless, and if such convenience
be afforded, retires for protection beneath some shell or fragment
of rock, from whence it soon re-appears, and repeats its gymnastic
exercises, which cease, however, for a few days, as soon as the new
coat is sufficiently hardened.
The prawn is an extremely interesting occupant of an aquarium, from
the fact of its being constantly on the move, and also on account
of the pretty blue and orange markings of its many-jointed legs,
and the singular transparent appearance of its body. This latter
feature is made still more notable when the animal happens to have the
ova attached, as the latter are opaque, and of a deep brown colour
approaching to black. By the prawn the act of exuviation seems to be
considered an event of no slight importance, and, although occurring
so frequently, is fraught with danger. Specimens oftener die at the
moulting time than at any other. In fact, unless I am very much
mistaken, they are then subject to some peculiar disease, which is
apt to prove fatal. At all events, several of my little captives,
after having performed their gymnastic movements (before alluded
to) for several days, turned sickly, and died. The commencement of
their illness was always denoted by a small, white, opaque dot that
mysteriously appeared in the centre of the body. This object speedily
increased in size, until it eventually spread over the entire animal.
Then, no longer diaphanous, the flesh of the prawn seemed composed of a
solid substance not unlike lime or pounded chalk.
The Shrimp is so common, and so well known, that a lengthened
description of it is unnecessary. I shall, therefore, merely record
an ingenious plan by which specimens of the _Crangon vulgaris_ may be
procured by visitors at the sea-side, who do not care to wade in the
water with a large net.
It is one generally pursued by Scotch boys as a mere amusement, for
neither shrimps nor prawns are eaten to any great extent by the
inhabitants of Scotland generally.
On arriving at a pool, a person will soon know whether shrimps are
contained therein, from the number of sand clouds that are raised by
these little crusty fellows at any intrusion upon their privacy. Many
persons employ a hand net, and pass it rapidly through the water,
thinking thereby to startle and entrap the animals in question.
Sometimes the plan succeeds, but more often it turns out a failure.
Instead of using the net, let the young zoologist stoop down, place the
palms of his hands suddenly upon the surface of the sand, then slowly
draw them near each other, at same time cautiously close the fingers,
and he will in all probability feel the objects of his search wriggling
to escape from his unwelcome and unfriendly grasp.
To satisfy curiosity, take one of the captured specimens and drop it in
the sand that surrounds the cavity in which your skill as a shrimper
has been exercised, and I will venture to assert that, in an instant,
the little creature will have disappeared as if by magic--such is
the wonderful rapidity with which the shrimp burrows itself. Even
when lying upon the surface a practised eye is required to detect the
presence of a shrimp, in consequence of its colour being of the exact
shade of the sand in which it hides. In clear pools its body is of
a light drab colour, which becomes changed to a dark tint when the
animal is located in a pool, the base of which is of a sombre hue.
The prawn, or shrimp, is somewhat of a gourmand, and requires to be fed
occasionally. The most simple food to give either, when in an aquarium,
is an open mussel or cockle. A marine worm, such for instance as the
_Terrebella_, however (as on one occasion I vexatiously discovered), is
a dainty more highly prized than the flesh of a bivalve, but one which
cannot often be indulged in from its comparative rarity.