| A | B |
|---|
| arthropod | characteristics include a tough exoskeleton, a series of joint appendages, and a segmented body |
| trilobite | oldest subphylum of arthropods; extinct |
| chelicerate | characterized by a two-part body and mouthparts called chelicerae |
| crustacean | characterized by a hard exoskeleton, two pairs of antennae, and mouthparts called mandibles |
| uniramian | characterized by on pair of antennae and appendages that do not branch |
| exoskeleton | system of external supporting structures |
| chitin | carbohydrate found in arthropod exoskeletons |
| molt | shed or get rid of an exoskeleton |
| metamorphosis | process of growth and development |
| pupa | stage in complete metamorphosis when the insect's body is totally rearranged |
| arachnid | include spiders, scorpions, ticks, and mites |
| mandible | mouthparts of crustaceans and insects |
| pheromone | specific chemical messenger that affects the behavior and/or development of other individuals of the same species |
| insect | characterized by a three-part body and has three pairs of legs attached to the thorax |
| centipede | characterized by a long wormlike body with 15 to 170 pairs of legs |
| millipede | characterized by a long wormlike body and each body segment contains two pairs of legs |
| cephalothorax | combination of the head and the thorax in crustaceans and chelicerates |
| abdomen | posterior end of chelicerates, crustaceans, and insects |
| head | anterior section of the body in insects |
| thorax | middle section of the body in insects |
| gills | type of respiration in aquatic arthropods |
| book gills | type of respiration found in horseshoe crabs |
| book lungs | type of respiration found in spiders and other arachnids |
| tracheal tubes | type of respiration found in most terrestrial arthropods with long tubes |
| antenna | sensory organs found at the head of most arthropods |
