<P> Mammals include the largest animal on the planet , the blue whale . The basic body type is a terrestrial quadruped , but some mammals are adapted for life at sea , in the air , in trees , underground or on two legs . The largest group of mammals , the placentals , have a placenta , which enables the feeding of the fetus during gestation . Mammals range in size from the 30 -- 40 mm ( 1.2 -- 1.6 in ) bumblebee bat to the 30 - meter ( 98 ft ) blue whale . With the exception of the five species of monotreme ( egg - laying mammals ) , all modern mammals give birth to live young . Most mammals , including the six most species - rich orders , belong to the placental group . The largest orders are the rodents , bats and Soricomorpha ( shrews and allies ) . The next three biggest orders , depending on the biological classification scheme used , are the Primates ( apes and monkeys ) , the Cetartiodactyla ( whales and even - toed ungulates ) , and the Carnivora ( cats , dogs , seals , and allies ) . </P>
<P> Mammals include the largest animal on the planet , the blue whale . The basic body type is a terrestrial quadruped , but some mammals are adapted for life at sea , in the air , in trees , underground or on two legs . The largest group of mammals , the placentals , have a placenta , which enables the feeding of the fetus during gestation . Mammals range in size from the 30 -- 40 mm ( 1.2 -- 1.6 in ) bumblebee bat to the 30 - meter ( 98 ft ) blue whale . With the exception of the five species of monotreme ( egg - laying mammals ) , all modern mammals give birth to live young . Most mammals , including the six most species - rich orders , belong to the placental group . The largest orders are the rodents , bats and Soricomorpha ( shrews and allies ) . The next three biggest orders , depending on the biological classification scheme used , are the Primates ( apes and monkeys ) , the Cetartiodactyla ( whales and even - toed ungulates ) , and the Carnivora ( cats , dogs , seals , and allies ) . </P>
5 animals that belong to the mammal group
5 animals that belong to the mammal group
rodents bats monkeys whales cats
rodents bats monkeys whales cats