First Fish - Basic Facts
Jessica
Fish were the first vertebrates to appear. The first vertebrates were jawless fish. An Ostracoderm, is an extinct jawless fish that existed about 510 million years ago. The name means "shell-skinned," and this fish was typically covered with scales and bony plates. Another example,"The Lamprey, has a round mouth without opposing jaws. It is disk-shaped, with teeth in more or less radiating rows and other teeth on the tongue. The teeth rasp off the skin of the victim, usually a fish, then sucks the blood." This fish appeared about 300 years ago and became extent 250 years ago.
The first fish, at some stage in there life history, had gill slits in a region of their head. They had developed gills and a simple sort of spinal nerve. Fish retain enough undifferentiated cells to be able to restore certain lost parts of the brain and spinal cords, as well as to regenerate portions of the heart.
In 1952, It was learned that a supposedly extinct fish, the Coelacanth, turned out to be common around the Comoro Islands.
The first boney fish is known as the sturgeon. It grew exceptionally large, had low mortality, lived a long time, and gave very few offspring. The oldest sturgeon fossil found was in North America and was dated to be 60 million years old.
Twenty-two different species of fish native to Lake Victoria have become extinct while 150 others are endangered due to voracious Nile Perch, overfishing, and pollution.Today there are an estimated 30,000 species of modern fish alive.
In 1981 Chinese cloned a golden carp, the first genes transferred from one animal to another by transferring genes from one species of mice to another at Ohio University.
Sources:
http://www.mbnet.mb.ca/w smith/evolution.html
http://ag.arizona.edu/tree/eukaryotes/animal/chondata/terrestral-vertebrates;ht
Manitoba Natural Resources.Frontier
School Division #48
Fish species vanish in Lake Victoria
Leonard P. Schultz
