Bony Fish

What are they?

The class bony fish is the group of fish that have true bones. This group itself can be divided into two sub groups on basis of the percentage of true bones in it .

The fish that have their bones composed mainly of true bones and not much of cartilage consists of the modern fish.

Characteristics

The fish that have their bones composed of partly true bones and partly cartilage.

The modern bony fish ( the one whose body has mostly true bones ) has about 20,000 species within itself. They thus form about 95 per cent of all of today's known kinds of fish. Some fishes have a totally bony skeleton. They have a special name - teleosts.

The name teleosts is made of two Greek words which mean complete and bone. The words themselves indicate the features of these fishes. Nearly all food fish, game fish, and aquarium fish that are used today are teleosts. They include many well known groups of fish including bass, catfish, cod, herring, minnows, trout, and tuna. Each group of these fish consists of a number of sub species within there broad group.

Despite the fact that some are well know, thousands' of them are still unknown to humans. They inhabit places that are rarely visited by humans. Many live in remote forest rivers or coral reefs. Some of them live deep in the oceans, still undiscovered by humans. It includes more than 100 kinds of deep sea anglers. These fish have fang like teeth and also their own light source - flashing light organs. This helps them navigate the deep ocean depths. They rarely come to the surface of the oceans.. if ever. They seem to be content to lead the deep ocean life hidden from the human eye. Many teleosts have strange names and even stranger colours. Some even have strange natures. Take the upside down catfish, for instance It definitely live up to it's name ( if not upside down to it) by swimming regularly on its back.

Many millions of years ago, the teleosts must have just originated, because there was only a few species of them. They were outnumbered by sharks and the ancestors of certain present-day bony fish. It is a wonder that they could survive against these monsters, but they did - and even flourished at it. They lived originally only in few parts of the world. There is a good reason for the vast number of species, mainly their incredible ability to adapt to various environments with surprising ease. Today, the species of teleosts differ in such a variety of ways, that there seems little in common among them. Some have become excellent swimmers and can swim at high speeds like the tuna and Sailfish. But others can hardly swim at all. The fast swimmers can dart in and out of the coral reefs, thus escaping from their enemies, while others barely move. Certain eel like teleosts are fin less and hence stand nowhere in comparison to the others as far as swimming is concerned. But they bury into the mud at the ocean floor and hence remain safe. Some have wing like fins that help them glide above the water, while still others have strong fins ( like the mudskipper ) and can hop about on land.

Other species of modern bony fishes include sturgeons, paddlefish, sturgeonfish and triggerfish. Sturgeons stand first as far as being the largest of freshwater fish is concerned. The largest sturgeon ever to be caught in history weighed almost 1,500 kilograms.

Under the class of Primitive bony fish , are include about 15 species of bichirs, coelacanths, and lungfish. Though there are 15 species, they make up less than even 1% of all the fish alive. These lived many many millions of years ago.

All the primitive bony fish of today live in fresh water, except ( another exception ) the coelacanths. Coelacanths live off the coast of Africa ( to the South East of it ).

From where did they evolve and when?

Varied, and not accurately known.