Fish

Fish were the first species to evolve a backbone and therefore were the first vertebrates. Fish live and breath under water, and fish have gills, fins, and scales. Fish are cold-blooded which means that their body temperature is the same as the temperature of the water. Two examples of scientific names are Astronotus ocellatus and Sphyraena barracuda. There are about 30,000 different species of fish in the world.

These are all different species of fish

Lionfish infestation in Atlantic Ocean a growing epidemic