Mammals

 The class Mammalia is one of the 7 which make up the subphyla Vertebrata (phylum Chordata). Mammals are vertebrates which are characterised by having young that are suckled on milk from the female parent, hair, and are endothermic. Manny mammals also have specialised teeth.

  The largest mammal ever to have been in existance is the blue whale. It is also the largest animal ever. Blue whales can grow as large as 100 feet in length, and weigh up to 130 tons. In comparison, the Mediterranean Water Shrew is around 1.5 inches long and weighs only a couple of ounces. The species of mammal that have the most complex behaviour, are humans (Homo sapiens), and they are capable of concious thought.