| A | B |
|---|
| ectotherm | an organism that needs sources of heat outside of itself; cold blooded |
| exoskeleton | a hard, external, supporting structure |
| metamorphosis | a phase in the life cycle of many animals during which a rapid change from the immature form of an organism to the adult form takes place |
| endotherm | an animal that can use the body heat from chemical reactions in the body's cells to maintain a constant body temperature; warm blooded |
| preening | the act of grooming and maintaining feathers |
| down | a soft feather that covers the body of young birds and provides insulation to adult birds |
| molting | shedding of an exoskeleton, skin, feathers, or hair to be replaced by new parts |
| contour | one of the most external feathers that cover a bird and that help determine its shape |
| placental | a mammal that nourishes its unborn offspring through a sac inside its uterus |
| carnivore | a mammal that has large canine teeth and special molar teeth for slicing meat |
| marsupial | a mammal that carries and nourishes its young in a pouch |
| monotreme | a mammal that lays eggs |
| communication | a transfer of a signal or message from one animal to another, resulting in a response |
| vertebrates | an animal that has a backbone |
| social behavior | interaction between animals of the same species |
| invertebrates | an animal without a backbone |
| brain | an organ that controls nerves through the body |
| gills | an organ that exchanges oxygen from the water with carbon dioxide from the blood |
| lung | an organ that exchanges oxygen from the air with carbon dioxide from the blood |
| tissues | collections of similar cells |
| cartilage | tough material that the flexible parts of our ears and nose are made of |
| antenna | a feeler that is on the head of an invertebrate, such as a crustacean or insect, that senses touch, taste, or smell |
| segment | any part of a larger structure, such as the body of an organism, that is set off by natural or arbitrary boundaries |
| embryo | plant or animal at an early stage of development |
| insects | What is the largest group of arthropods? |
| reptiles | Which animals live their entire lives on land, and are born with lungs? |
| amphibians | Which animals live part of their lives in water and part of their lives on land? |
| spiders | What arthropod kills more insect pests than any other animal? |
| cnidarians | Which invertebrates have stinging cells? |
| sponges | What are the simplest invertebrates? |
