The term Urochordata is derived from the Greek word oura meaning tail and chorda meaning chord. Animals which in the larval stage have a notochord in the tail and the body is covered by a test or tunic are called Urochordata. These are tail cordata. These are commonly called tunicates. So named because their bodies are covered with cellulose called tunic or testa. Some species of this subspecies are called sea fountains because they forcefully siphon water. Tunicates feed on suspension feeders (small food). Scientist Lamarck named them Tunicata. Their number of species is 2,804.