Posts from the ‘Bony Fish’ Category

What Is A Coelacanth?

Coecalanth

Coecalanth

A coelacanth (pronounced SEE, luh kanth) is a large rare fish from deep in the oceans around Africa.

What makes the coelacanth so unusual is that it is perhaps the world’s most primitive bony fish. It was once thought to have been extinct. But in 1938, a living coelacanth was caught by a fisherman off the east coast of Africa.

Almost unchanged since its origin, this strange-looking fish was bright blue in color. It was five feet long and weighed 125 pounds. It had leglike fins, probably used for crawling about in the sea, and its head was covered with thick scales.

If the fisherman had found a living dinosaur, he would not have attracted more attention in the scientific world.

Scientists  knew the coelacanth only from fossils and had assumed that the prehistoric fish had died out 60-million years ago!

Since the discovery of a live coelacanth, several more of these “living fossils” have been found.Dick Rogers

Why fish don’t sink?

Fish

A fish, with its bones and scales, is heavier than the water it displaces. Under normal circumstances, it would tend to sink.  But most bony fishes have a balloon-like sac inside their bodies called an “air bladder” that acts as a float to keep them from sinking.  The air bladder fills up with some of the oxygen dissolved in the fish’s blood.

Some fish, such as pike and catfish gulp air at the surface of the water to fill their air bladders.  A shark has no air bladder to buoy it up.  It must constantly be swimming in order to keep from sinking. – Dick Rogers