| A | B |
|---|
| cell | basic unit of structure and function in animals |
| tissue | group of similar cells working together |
| organ | group of different tissues working together |
| organ system | group of different organs working together |
| adaptation | structure or behavior that allows an animal to survive or reproduce in its environment |
| sexual reproduction | produces new organism from the joining of sex cells; offspring differ from the parents |
| fertilization | joining of sperm and egg |
| asexual reproduction | produces new organism identical to the parent; involves only one parent |
| phylum | classification group smaller than a kingdom |
| vertebrate | animal with backbone |
| invertebrate | animal without a backbone |
| bilateral symmetry | body plan with one line of symmetry dividing animal into two halves that are mirror images |
| radial symmetry | body plan that has many lines of symmetry that pass through a central point |
| larva | immature form of an animal that looks different from the adult form |
| sponge | invertebrate with no line of symmetry having no tissues or organs |
| cnidarian | invertebrate that uses stinging cells to capture food and defend itself |
| polyp | cnidarian that is vase-shaped and is usually attached to a hard surface underwater |
| medusa | cnidarian body plan that is bowl-shaped and free swimming |
| colony | group of individual organisms living together |
| coral reef | a stony structure made of dead coral's exoskeletons; home to a diverse group of living things |
| parasite | organism that lives on or in another organism and harms it |
| host | organism on or in which a parasite lives |
| free-living organism | organism that does not live on or in another organism |
| scavenger | organism that feeds on dead or decaying material |
| anus | opening through which waste is removed from the body |
| closed circulatory system | one in which blood moves through connected blood vessels |
| flatworm | flat, soft worms |
| roundworm | tiny, cylindrical worms with a digestive system like a tube open at both ends |
| segmented worm | worm whose body is made of many linked sections |
