BONY FISHES--TELEOSTOMI
We come now to the fishes proper--those with skeletons of bone,
although in some of the lower forms the ossification is incomplete. The
mouth contains supplementary tooth-bearing bones that form secondary
jaws corresponding to the functional jaws of the higher craniates;
hence the group name "Teleostomi," or perfect-mouthed fishes. The body,
as a rule, is coated with scales, and a gill cover (operculum) is
always present.
The Teleostomi include four orders, the Crossopterygii, the
Chondrostei, the Holostei, and the Teleostei.
The crossopterygians are mostly strange extinct fishes found as fossils
from the Devonian down; but some have survived, and live in the
sluggish African rivers an eellike existence, of which the bichir of
the Nile is a familiar example. The Chondrostei also are largely fishes
of the Paleozoic time, but two families survive to the present--the
spoonbills and the sturgeons. Of the former one species is Chinese,
and the other is the shovel-nosed spoonbill or paddlefish of the lower
Mississippi River. It is a big, sluggish creature, that stirs up the
mud with its long flat beak, and consumes it, getting sustenance from
the minute organisms it contains. They make caviar from its eggs. As
for the sturgeons, we have five species in the United States, and one
abounds in the Black Sea and the rivers that drain into it, from whose
eggs the Russian caviar is made. One or two species are exclusively
fresh-water, but most sturgeons are migratory fishes, living in the
sea, but ascending rivers for spawning. Their food consists of worms,
mollusks, the smaller fishes and aquatic plants; and in feeding the
mouth is protruded downward in the form of a cylindrical, spout-like
structure and thrust into the mud. Our common eastern-coast sturgeon is
also a native of the Mediterranean and French coasts, and was formerly
in England a "royal" fish, reserved to the king's use.
Of the third order, Holostei or "ganoids," whose history may be traced
in fossils almost to the earliest of fossiliferous rocks, we possess
in our rivers the only two survivors: one is the many-named bowfin of
the Mississippi Valley, and the other the widely distributed billfish
or gar pike. Both these relics of a very ancient order are of great
interest to naturalists; and the names "mudfish," "John H. Grindle,"
and many others, show how well known the bowfin is to the farmer boys.
The bowfin attains a length of about two feet and a weight of twelve
pounds, and, unlike its cousins the garfishes, is covered with hard,
rounded scales; the forepart of the body is cylindrical, the head stout
and blunt, and the mouth filled with powerful teeth. It is exceedingly
hardy, enduring absence from the water for a long time, as well as
grievous injury; hence the young are the favorite bait of anglers in
the Mississippi Valley, and make interesting captives in an aquarium,
where, however, nothing else but snails can remain alive. These fish
are strong, active, voracious and gamy. They feed on all sorts of small
aquatic creatures.
The garfish (or more properly gar pike, Lepidosteus, because certain
sea fishes of another sort are also called gars) is an elongated active
fish of our rivers, covered with hard, flat, ivorylike scales set in
oblique rows, and its snout is prolonged into a bill filled with sharp
teeth. They have many peculiarities of structure indicating their
ancient ganoid lineage; and besides our common species two others are
known, one of which, the alligator gar, belongs to the Gulf Coast and
Central American rivers. These gars are nocturnal and predatory in
their habits, and in early summer resort in large numbers to shallows
to lay their eggs, which are covered with a sticky envelope that
adheres to any object on which they fall. The long bill develops after
infancy.