The names of different species of fish include etheostoma nigrum, or the johnny darter; Mola mola, or ocean sunfish; Moxostoma carinatum, or the river redhorse; Rhincodon typus, or the whale shark, and Sphyrna mokarran, the great hammerhead shark. The johnny darter is found in North America.
Johnny darters are found in creeks, streams and rivers in the eastern part of the continent and westward to the Rocky Mountains. They are slender fish that only grow to be about 2 inches long. The male aggressively guards the eggs.
The ocean sunfish is the largest bony fish in the world. The whale shark, which is the largest fish, has a skeleton made of cartilage. The sunfish grows to 11 feet long and can weigh as much as 5,000 pounds. Because their back fins don't develop, the fish has an odd, roundish shape which gives it its Latin name,"mola" which means millstone.
The river redhorse is also a freshwater fish that is native to North America. It is a bottom-feeding fish that feeds on snails and crustaceans.
Though the whale shark is an enormous fish, it feeds largely on plankton and small marine animals. Though it can grow to 40 feet long and weigh 15 tons, it is harmless to humans. This is not quite true of the great hammerhead shark, whose oddly shaped head gives it its name. This shark migrates throughout the warm waters all over the world and gives birth to live young.