“During the summers of 1842 and 1843, while searching for the naked
mollusks of the county, I occasionally discovered portions of sea-weed
and the common coralline (_Corallina officinalis_) hanging from the
rocks in pear-shaped masses, variously intermingled with each other.
On one occasion, having observed that the mass was very curiously
bound together by a slender, silken-looking thread, it was torn open,
and the centre was found to be occupied by a mass of transparent,
amber-coloured ova, each being about the tenth of an inch in diameter.
Though examined on the spot with a lens, nothing could be discovered
to indicate their character. They were, however, kept in a basin, and
daily supplied with sea-water, and eventually proved to be the young
of some fish. The nest varies a great deal in size, but rarely exceeds
six inches in length, or four inches in breadth. It is pear-shaped, and
composed of sea-weed or the common coralline as they hang suspended
from the rock. They are brought together, without being detached from
their places of growth, by a delicate opaque white thread. This thread
is highly elastic, and very much resembles silk, both in appearance
and texture: this is brought round the plants, and tightly binds them
together, plant after plant, till the ova, which are deposited early,
are completely hidden from view. This silk-like thread is passed in all
directions through and around the mass, in a very complicated manner.
At first the thread is semi-fluid, but by exposure it solidifies; and
hence contracts and binds the substance forming the nest so closely
together that it is able to withstand the violence of the sea, and
may be thrown carelessly about without derangement. In the centre are
deposited the ova, very similar to the masses of frog-spawn in ditches.
“Some of these nests are formed in pools, and are consequently always
in water: others are frequently to be found between tide-marks, in
situations where they hang dry for several hours in the day; but
whether in the water or liable to hang dry, they are always carefully
watched by the adult animal. On one occasion I repeatedly visited one
every day for three weeks, and invariably found it guarded. The old
fish would examine it on all sides, and then retire for a short time,
but soon returned to renew the examination. On several occasions I laid
the eggs bare, by removing a portion of the nest; but when this was
discovered, great exertions were made to re-cover them. By the mouth of
the fish the edges of the opening were again drawn together, and other
portions torn from their attachments and brought over the orifice, till
the ova were again hid from view. And as great force was sometimes
necessary to effect this, the fish would thrust its snout into the
nest as far as the eyes, and then jerk backwards till the object was
effected. While thus engaged it would suffer itself to be taken by
the hand, but repelled any attack made on the nest, and quitted not
its post so long as I remained; and to those nests that were left
dry between tide-marks, the guardian fish always returned with the
returning tide, nor did they quit the post to any great distance till
again carried away by the receding tide.”
It is worthy of note that the newly-hatched young from these nests
were so unlike the full-grown Stickleback, and so like the common
smooth Blenny, that Mr. Couch concluded that there had been some error
in his observation, and that the nest truly belonged to the latter
fish. Further research, however, proved that the Stickleback was
indeed the parent; and the transition from the infantile Blenny-like
outline of the face, high, bluff, and almost perpendicular, to the true
Stickleback outline, long, slender, pointed, with the far-projecting
lower jaw, is something remarkable.