Marsupial Mammals What is a Marsupial? Marsupials are a group of mammals that have an external pouch located on their mother's abdomen in which they carry their young. Most marsupials live in Australia, where they have evolved into some unique and unusual animals. Marsupials range in size from the 1.8 meter tall red kangaroo which weighs 90kgs to the tiny, shrew-like long-tailed planigale which is just 6 cm in length and weighs only 4 gms.
Whale ribs loosely articulate with their thoracic vertebrae at the proximal end, but they do not form a rigid rib cage. This adaptation allows the chest to compress during deep dives as opposed to resisting the force of water pressure.
Toothed whale. The toothed whales (systematic name Odontoceti) are a parvorder of cetaceans that includes all the dolphins and porpoises, as well as the whales that have teeth, such as the beaked whales and sperm whales. Seventy-three species of toothed whales (also called odontocetes) are described.