The Class: Chondrichthyes
The sea creatures that make up this class are, Sharks, Skates, Rays, and specific types of Fish. The organisms in this class had once appeared about, four hundred and fifty million years ago, and some species in this class cease to exist in the twenty-first century, due to many factors, one of which is, natural selection. Most species in this class are also used as ingredients for medicine and food. Characteristics that all of these fish share include:
- Have scales that are similar to teeth , called denticles
- Have paired fins (pectoral & pelvic fins) for more efficient swimming
- Have five to seven gill slits per side and no swim bladder
- They are the plankton feeders