| A | B |
|---|
| Amniotic egg | An egg in which the embryo is protected by a membrane called an amnion. In addition, the egg is covered in a hard or leathery covering. |
| Contour feathers | Feathers with hooked and smooth barbules, allowing the barbules to interlock |
| Down feathers | Feathers with smooth barbules but no hooked barbules |
| Endothermic | A creature is endothermic if it has an internal mechanism by which it can regulate its own body temperature, keeping it constant. |
| Gestation | The period of time during which an embryo develops before being born |
| Hemotoxin | A poison that attacks the red blood cells and blood vessels, destroying circulation |
| Mammary glands | Specialized organs in mammals that produce milk to nourish the young |
| Neurotoxin | A poison that attacks the nervous system, causing blindness, paralysis, or suffocation |
| Placenta | A structure that allows nutrients and gases to pass between the mother and the embryo |
