| A | B |
|---|
| preening | grooming and maintaining feathers by spreading oil |
| molting | the shedding of exoskeleton, skin, feathers, or hair that will be replaced |
| down feathers | fluffy feathers that lie next to a bird's body |
| contour feathers | the external feathers that cover a bird and that help determine it's shape |
| crop | stores stones that sid in digestion |
| gizzards | grind up food with stones from the crop |
| air sac | stores air; attached to the lungs |
| keel | large breast bone; aids in flight |
| lift | the upward force on a bird's wings |
| brooding | the act of sitting on eggs and using body heat to keep them warm |
| precocial | active soon after hatching |
| altricial | hatchlings with no feathers and closed eyes; depend on parents after birth |
| mammary glands | structures that make milk |
| diaphragm | large muscle that helps bring air into the lungs |
| canines | large stabbing teeth that are a characteristic of certain mammals |
| molars | flat, grinding back teeth |
| incisors | cutting teeth |
| placental mammal | mammal whose embryos develop in the mother's body |
| uterus | organ in a female body that is home to the embryo |
| placenta | organ that attaches the embryo to the uterus; carries food and oxygen to the embryo and carries wastes away |
| gestation period | the length of time between fertilization and birth |
| insectivores | pointy snouts; eat insects and includes moles and shrews |
| rodents | live on every continent except Antartica; teeth continually grow in their jaws; rats, mice, squirrels |
| carnivores | have large canine teeth for ripping flesh |
| pinnipeds | flesh eating marine animals; include seals and walrusses |
| bats | flying mammals |
| cetaceans | wales, dolphins, and porpoises |
| primates | have five fingers on each hand with flat nails and opposable thumbs; humans monkeys, apes |
| monotreme | mammal that lays eggs |
| marsupials | mammals that carry and nourish young in a pouch |
