The word Vertebrata is derived from the Latin word vertebratus meaning having a backbone. Animals in which the embryonic notochord is fully replaced by bony or cartilaginous vertebrae are called Vertebrata. Vertebrata or vertebrates are known as higher order animals. Because their brain is located in the cranium, their other name is craniata. Their species number is 66,178 (IUCN, 2014).
Vertebrates (fish) have been in the ocean for over 150 million years. Hands and feet evolved in a group of vertebrates about 365 million years ago. As a result, they qualify as amphibians to live in water and on land. Over time, the descendants of amphibians adapted and evolved into reptiles, birds and mammals.