A Guide to the Study of Fishes, Volume 1 (of 2)Jordan, David Starr
History
A Guide to the Study of Fishes, Volume 1 (of 2)
Jordan, David Starr
Fishes; Fishes -- Bibliography; Zoology -- History
"In some individuals the eggs had been recently laid, in others they
were hatched and the foetus had grown at the expense of some other food
than that derived from the yolk, as this last was not proportionally
diminished in size, and the foetus weighed more than the undeveloped
egg. The number of eggs contained in the mouth was between twenty
and thirty. The mouth and branchial cavity were very much distended,
rounding out and distorting the whole hyoid and branchiostegal region.
Some of the eggs even partially protruded from the mouth. The ova were
not bruised or torn as if they had been bitten or forcibly held by the
teeth. In many instances the foetuses were still alive, though the
parent had been dead for many hours.
"No young or eggs were found in the stomach, although the mouth was
crammed to its fullest capacity.
"The above observations apply to njinge-njinge. With regard to
jarra-bakka, I had but few opportunities for dissection, but in several
instances the same conditions of the eggs were noticed as stated above;
and in one instance, besides some nearly mature foetuses contained in
the mouth, two or three were squeezed apparently from the stomach,
but not bearing any marks of violence or of the action of the gastric
fluid. It is probable that these found their way into that last cavity
after death, in consequence of the relaxation of the sphincter which
separates the cavities of the mouth and the stomach. These facts lead
to the conclusion that this is a mouth gestation, as the eggs are found
there in all stages of development, and even for some time after they
are hatched.
"The question will be very naturally asked, how under such
circumstances these fishes are able to secure and swallow their food. I
have made no observations bearing upon such a question. Unless the food
consists of very minute particles it would seem necessary that during
the time of feeding the eggs should be disgorged. If this supposition
be correct, it would give a very probable explanation of the only fact
which might be considered at variance with the conclusion stated above,
viz., that we have in these fishes a mouth gestation. In the mass
of eggs with which the mouth is filled I have occasionally found the
eggs, rarely more than one or two, of another species. The only way in
which their presence may be accounted for, it seems to me, is by the
supposition that while feeding the eggs are disgorged, and as these
fishes are gregarious in their habits, when the ova are recovered the
stray eggs of another species may be introduced into the mouth among
those which naturally belong there."
One of the earliest accounts of this curious habit which we have seen
is that by Dr. Günther, referring to specimens of _Tachysurus fissus_
from Cayenne received from Prof. R. Owen:
Public-domain text, read in full here on John Shaqi.
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