a type of mammal from Australasia or South or Central America that is not completely developed when it is born and is carried around in a pouch
a primary grouping consisting of animals constructed on a similar general plan, and thought to be evolutionarily related
if an organism uses energy to regulate its body temperature internally
the short, fine, soft hair of certain animals.
a dome-shaped muscular partition separating the thorax from the abdomen in mammals. It plays a major role in breathing, as its contraction increases the volume of the thorax and so inflates the lungs.
a skeleton that is on the inside of a body, like humans, dogs, or some fish
firm, whitish, flexible connective tissue found in various forms in the larynx and respiratory tract, in structures such as the external ear, and in the articulating surfaces of joints. It is more widespread in the infant skeleton, being replaced by bone during growth.
the release of both sperm and eggs into an external environment
an organ in the human or animal body which secretes particular chemical substances for use in the body or for discharge into the surroundings.
an animal or person that eats food of both plant and animal origin.
an animal of a large group distinguished by the possession of a backbone or spinal column, including mammals, birds, reptiles, amphibians, and fishes.
a series of vertebrae extending from the skull to the small of the back, enclosing the spinal cord and providing support for the thorax and abdomen; the backbone.
(in an insect or amphibian) the process of transformation from an immature form to an adult form in two or more distinct stages.
each of the pair of organs situated within the rib cage, consisting of elastic sacs with branching passages into which air is drawn, so that oxygen can pass into the blood and carbon dioxide be removed. Lungs are characteristic of vertebrates other than fish, though similar structures are present in some other animal groups.
denoting or relating to the human female breasts or the milk-secreting organs of other mammals.
the paired respiratory organ of fishes and some amphibians, by which oxygen is extracted from water flowing over surfaces within or attached to the walls of the pharynx.