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| a type of symmetry in which parts on both sides of a single dividing line are mirror images of each other; characteristic of humans, most animals, and some plants | bilateral symmetry |
| a type of symmetry in which the parts branch out in all directions from a common center, such as in a starfish or a daisy | radial symmetry |
| the condition of lacking symmetry | asymmetry |
| any flesh-eating (carnivorous) animal or insect-eating plant; a mammal of the order Carnivora | carnivore |
| an animal that eats plants | herbivore |
| describing an organism that eats both plants and flesh | omnivore |
| describing an animal that is active in the daytime; opposite of nocturnal | diurnal |
| describing an animal that is active at night; opposite of diurnal | nocturnal |
| an organism that is in a very early stage of development, such as a plant within a developing seed or a human a few days after fertilization | embryo |
| the stage of development of an unborn human or animal at which it can be recognized as a young individual | fetus |
| the structure in the wall of the uterus by means of which the developing offspring receives nourishment and eliminates wastes | placenta |
| in humans and in animals which bear live young, the period between fertilization and birth | gestation period |
| the internal bone or cartilage skeleton of a vertebrate | endoskeleton |
| describing a type of animal or plant that is no longer found alive on the earch | extinct |
| describing an animal or plant that still exists today but is in danger of extinction | endagered |
| a state of extremely slow metabolism and lowered body temperature that enables certain mammals to survive harsh winter conditions | hibernation |
| describing an organism that maintains a relatively stable body temperature, usually by means of internal factors (such as shifting blood circulation, sweating, etc.) | homeothermic |
| the hornlike covering on the feet of such animals as cattle, deer, horses, and swine | hoofs |
| describing an animal (or plant) that eats insects | insectivorous |
| any insect-eating animal or plant; specifically, a mammal of the class Insectivora, such as a shrew, mole, or hedgehog | insectivore |
| any animal of the order Marsupialia, characterized by an abdominal pouch, or marsupium; examples include the kangaroo, opossum, and koala | marsupial |
| the pouch in the abdoment of a marsupial in which the young are raised | marsupium |
| capable of moving from place to place; opposite of sensile | motile |
| describing an animal that is attached to one location but is able to move the surrounding meduum (air or water) toward itself for the purpose of trapping food | sessile |
| a flexible, unsegmented rod that forms the "backbone" of some animals (such as sharks and coelacanths) | notochord |
| a tail designed for grasping or seizing | prehensile tail |
| any of the gnawing animals of the order Rodentia; examples include mice, rate, and squirrels | rodent |
| the first division of a ruminant's stomach, which serves to hold food until it can be chewed thoroughly | rumen |
| an animal with four legs or appendages | tetrapod |
| a hoofed animal | ungulate |
| any even-toed ungulate that "chews the cud"; examples include cattle, deer, goats, and giraffes | ruminant |
| any group of animals characterized by the presence of a backbone or notochord, a spinal cord with a brain at the anterior(front) end, and a skull to protect the brain; examples incl. mammals, birds, reptiles, amphibians, and fish | vertebrates |
| an animal without a backbone or spinal column | invertebrates |
| referring to an animal that reproduces by nourishing the young internally and bearing thme alive when they are sufficiently developed | viviparous |
| describing an animal that reproduces by means of eggs hatched outside the body | oviparous |
