Because, it is supposed, by its means the fish attaches itself to the sides of other fishes, or to the bottoms of ships, when it is carried forward without any exertion of its own; and, during storms, adhesion to rocks may save a weak fish from being tossed about by the fury of the waves: other purposes, probably, remain to be discovered.
About five years since, a correspondent of the Quarterly Journal of Science, drew up, in Dublin harbour, a whiting pollack, under whose throat a sea-lamprey had buried its head, and thus firmly attached itself. When separated, the lamprey darted on its prey, to which it again adhered firmly.
Because it enables them to perceive the approach of their foes, and it is the principal instrument by which they obtain their food. The amateur in flyfishing often tempts the fish with one kind of fly, but in vain; and, upon substituting another in its place, of a different form or colour, succeeds in the capture. These motions of fish are all regulated by the eye: hence some fish will bite as readily at a bit of red cloth as at a piece of flesh. - Fleming.
The eyes of fishes are larger in proportion to the size of their bodies, than in quadrupeds, as we find the eye of the cod-fish equal in size to that of an ox.
Because the eye rests on a thin cartilaginous pulley, which is attached to the bottom of the orbit, and thus increases its motions. In other fishes, the motions of the eye are confined.
Because they have no eye-lids, nor any membrane to close and cover their eyes, as animals that sleep have.
Because it grows as the fish increases in size, and consequently its magnitude is in the direct ratio of the bulk and age of the animal.
Because most of them feel acutely on the abdomen, and in the lips. It is doubtful whether their tongue be an organ of taste, and in what degree it may serve that purpose. - Blumenbach.
Because, probably, a great number of species live in succession on each other, according to their strength and voracity.
The following may convey some idea of the prolific powers of fish: -
Carp . . produces ....
The rays and sharks seem to produce but a very limited number. The utmost, stated by different observers, is 26 and 30. It should be added, that there is no estimated proportion between the number of eggs deposited, and the number of fish which arrive at maturity. The eggs are eagerly sought after by other fishes, by aquatic birds, and reptiles; and in the young state, they are pursued by their own species, as well as by beings belonging to other classes.