- Down Feather-a fluffy, insulating feather that lies next to a bird’s body.
- Contour feather-a feather made of stiff, central shaft with many sides of borecole called barbs.
- Preening-the activity in which a bird uses its beak to spread oil on its feathers.
- Lift- an upward force on an object caused by different in pressure above and below the objects; lift opposites the downward
of a pull of gravity.
- Brooding-when a bird sits on an egg until they hatch.
- Mammary gland-glands that secrete a nitrous fluid called milk.
- Diaphragm-the sheet of muscle underneath the lungs of mammals that helps draw air into the lungs.
- Monochrome-a mammal that lays eggs.
- Marsupial-a mammals that gives birth to live; paritillay-developed young that continues to develop inside the mothers
pouch or skin fold.
- Placental mammal-a mammal that mourners its unborn offspring with a placenta inside the uterus and gives birth to well-developed
- Gestation period-the time during which an embryo develops within the mother.