| A | B |
|---|
| alimentary canal | digestive tract consisting of a tube running between a mouth and an anus |
| ammonite | shelled cephalopod that was the dominant invertebrate predator until the end of the Cretaceous period |
| amoebocyte | amoeba-like cell that moves by pseudopodia |
| arthropod | segmented coelomate with a chitinous exoskeleton |
| book lung | organ of gas exchange in spiders |
| brachiopod | marine lophophorate with a shell divided into dorsal and ventral halves |
| chelicera | clawlike feeding appendages characteristic of cheliceriforms |
| cheliceriform | arthropod that has chelicera |
| choanocyte | flagellated feeding cell found in sponges |
| closed circulatory system | blood is confined to vessels and is kept separate from the interstitial fluid |
| cnidocyte | specialized cell with a fine coiled thread |
| complete metamorphosis | transformation of a larva into an adult that looks very different than the larva |
| copepod | small crustaceans that are important members of marine and freshwater plankton |
| crustacean | subphylum of arthropods that includes lobsters |
| cuticle | exoskeleton of an arthropod |
| decapod | group of crustaceans that includes lobsters |
| echinoderm | marine deuterostome with a water vascular system and |
| ectoproct | sessile, colonial lophophorate commonly called a bryozoan |
| eurypterid | extinct carnivorous cheliceriform also called a water scorpion |
| exoskeleton | hard encasement provides protection and points of attachment for muscles |
| foot | muscular structure usually used for movement in molluscs |
| gastrovascular cavity | pouch that serves as the site of extracellular digestion and a passageway to disperse materials |
| hermaphrodite | both male and female in sexual reproduction by producing both sperm and eggs |
| hexopod | insect or closely related wingless arthropod |
| incomplete metamorphosis | young resemble adults but are smaller and have different body proportions |
| invertebrate | animal without a backbone |
| isopod | largest groups of crustaceans terrestrial isopods are the pill bugs |
| mandible | jaw-like feeding appendages found in myriapods |
| mantle | fold of tissue in molluscs that drapes over the visceral mass and may secrete a shell |
| mantle cavity | water-filled chamber that houses the gills |
| medusa | floating flattened, mouth-down version of the cnidarian body plan |
| mesohyl | gelatinous region between the two layers of cells of a sponge |
| molting | process in arthropods in which the exoskeleton is shed at intervals |
| myriapod | terrestrial arthropod with many body segments and one or two pairs of legs per segment |
| nematocyst | stinging capsule-like organelle in a cnidocyt |
| open circulatory system | fluid called hemolymph bathes the tissues and organs directly |
| osculum | large opening in a sponge that connects the spongocoel to the environmen |
| parthenogenesis | females produce offspring from unfertilized eggs |
| phoronids | tube-dwelling marine lophophorate |
| planarian | free-living flatworm found in unpolluted ponds and streams |
| polyp | sessile variant of the cnidarian body plan |
| radula | straplike rasping organ used by many molluscs during feeding |
| spongocoel | central cavity of a sponge |
| suspension-feeder | sifts small food particles from the water |
| torsion | characteristic of gastropods in which the body rotates during development |
| trilobite | extinct arthropod with pronounced segmentation and appendages |
| trochophore larva | distinctive larval stage observed in annelids and molluscs |
| tube foot | extensions of an echinoderm’s water vascular system |
| visceral mass | containing most of the internal organs |
| water vascular system | network of hydraulic canals unique to echinoderms which function in locomotion |
