| A | B |
|---|
| crop | internal storage tank for storing food inside the body after swallowing |
| down feathers | specialized to trap heat and keep the bird warm |
| gizzard | thick walled muscle that squeezes and grinds food |
| lift | difference in air pressure above and below the wings as a bird moves though the air |
| contour feather | large feathers that shape a bird's body |
| mammals | endothermic vertebrates that have four chambered heart and skin covered with fur or hair |
| monotremes | egg laying mammals |
| marsupials | mammals whose young are born at an early stage of development and continue to develop in the mothers pouch |
