Fishes

Almost three-forths of the world's surface is covered in water. This water is home to over 20,000 different species of fish. The earliest fossils of fish date back over 400 million years.

On this page:

Fishes

Top of Page

There are a wide variety of fish -- from the goby which is less than one half an inch long, to the whale shark which can be over 60 feet long.

Fishes are vertebrates that have a skeleton made of either bone or cartilage. About 95% of fishes have skeletons made of bone. These bony fishes have a swim bladder, a gas-filled sac, that they can inflate or deflate allowing them to float in the water even when not swimming. Fishes with a cartilage skeleton tend to be heavier than water and sink. They must swim to keep afloat. Cartilage fish include the ray and the shark.

Most fish swim using a tail fin. Muscles in the tail fin move it from side to side, forcing water backward, and propeling the fish forward. Other fins help the fish change direction and stop. Pectoral fins on their side help them swim up and down. Dorsal and anal fins on the top and bottom keep the fish upright. Pelvic fins on the underside help steer left and right.

Fish
Most fish breathe through gills. Gills perform the gas exchange between the water and the fish's blood. They allow the fish to breathe oxygen in the water.

Many fish eat plants, while others such as the shark, eat other fish.

Shark
If you are interested in more information fish, check out our fish video collection.

 

Google

Other related pages:



 

Books on Fishes

Top of Page

   

 

Other links on Fishes

Top of Page

   
 

Top of Page

 

Facebook and Twitter

Copyright 1998-2009 Kidport