| A | B |
|---|
| invertebrate | animal without a backbone |
| vertebrae | small bones making the backbone |
| pore | a small hole or opening |
| stinging cells | cells that contain a poisonous thread |
| tentacle | an armlike part |
| flatworm | a worm with a flattened body and only one body opening |
| parasite | a living thing that lives on in another living thing (host) and harms the host |
| roundworm | a worm that has a round body and two body openings |
| segmented worm | a worm that has a body divided into segments or sections |
| mollusk | an invertebrate that has a soft body |
| mantle | fleshy covering that protects the organs of a mollusk |
| echinoderm | spiny-skinned invertebrate that lives in the ocean |
| tube foot | a hollow structure with a sucker at the end |
| arthropod | an animal with jointed legs, a segmented body, and a hard outer covering |
| exoskeleton | the hard outer covering of all arthropods |
| molt | to shed the outer body covering |
| thorax | the middle part of an insect's body which has the legs attached to it |
| head | the part of an insect that contains the mouth and most of the sense organs |
| abdomen | the rear part of the insect's body which contains the organs for digesting and reproduction |
| crustacean | an arthropod which has two body sections and two pairs of antennae, usually aquatic |
| arachnid | an arthropod which has two body sectons but no antennae |
| insect | an arthropod which has three body sections |
