| A | B |
|---|
| Carnivore | animal that eats only other animals or the remains of other animals; mammals having large, sharp canine teeth and strong jaw muscles for eating flesh |
| Contour feather | strong, light weight feathers that give birds their coloring and shape and that are used for flight |
| Down feather | soft, fluffy feathers that provide an insulating layer next to the skin of adult birds and that cover the bodies of young birds |
| Endotherm | vertebrate animal with a nearly constant internal temperature |
| Gestation period | period during which an embryo develops in the uterus; the length of time varies among species |
| Herbivore | animal that eats only plants or parts of plants; mammals with large premolars and molars for eating only plants |
| Mammals | endothermic vertebrates that have hair, teeth specialized for eating certain foods, and mammary glands; in females, mammary glands produce milk for feeding their young |
| Mammary gland | glands of mammals; in females, produce milk to feed their young |
| Marsupial | a mammal with an external pouch for the development of its immature young |
| Monotreme | a mammal that lays eggs with tough, leathery shells and whose mammary glands do not have nipples |
| Omnivore | animal that eats plants and animals or animal flesh; mammals with incisors, canine teeth, and flat molars for eating plants and other animals |
| Placenta | an organ that develops from tissues of the embryo and tissues that line the inside of the uterus and that absorbs oxygen and food from the mother’s blood |
| Placental | a mammal whose offspring develop inside the female’s uterus |
| Preening | process in which a bird rubs oil from an oil gland over its feathers to condition them |
| Umbilical cord | connects the embryo to the placenta; moves food and oxygen from the placenta to the embryo and removes the embryo’s waste products |
