| A | B |
|---|
| sea otter | a carnivorous placental mammal with a well-developed brain and good underwater vision |
| umbilical cord | in placental mammals, a bundle of blood vessels connecting the placenta to the embryo transports nutrients and oxygen from the placenta to the embryo and carries away wastes |
| carnivore | an animal that eats only other animals |
| contour feather | on birds, the stong, lightweight feathers that are used for flight and that gave birds their coloring and sleek shape |
| herbivore | an animal that eats only plants |
| gestation period | the time betweem fertilization and birth during which the embryo develops in the uterus |
| down feater | on birds, the soft fluffy insulating featers that cover their skin |
| incubate | to keep an egg or newborn animal warm; the heat helps eggs develop until they hatch and helps young to survive |
| mammal | an ecdthermic vertebrate with insulating hair and mammary glands |
| mammary gland | glands in female mammals that produce milk for feeding young |
| omnivore | an animal that eats both plants and animals |
| monotreme | a mammal that lays eggs having tough, leathery shells; for example, the duck-billed platypus |
| marsupial | a mammal with a pouch on its abdomen for carrying and nursing its young |
| placenta | in placental mammals, the saclike organ developed by a growing embryo; attaches to the uterus; absorbs food and oxygen form the mother's blood |
| placental mammal | a mammal whose ypung develop inside the femal in the uterus |
| preening | a behavior of birds in which a bird uses its beak to rub oil over its feathers to condition them and help make them water repellent |
