| A | B |
|---|
| trochophore | the larval stage of development |
| mollusks | invertebrates such as clams, snails, slugs, and octopuses |
| head-foot | the head made up of the mouth and a variety of sensory organs and the foot, a large muscular organ used for locomotion |
| visceral mass | contains the heart, digestion organs, excretion, and reproductive organs |
| mantle | layer of epidermis that covers the visceal mass |
| mantle cavity | the space between the mantle and the visceral mass |
| ganglia | paired clusters of nerve cells |
| radula | flexible tongue like strip of tissue covered with tough abrasive teeth that point backward |
| gastropods | the largest and most diverse class of mollusks including snails, abalones, and conchs |
| torsion | process during larval development when the visceral mass twists 180 degrees bringing the mantle cavity, gills, and anus to the front of the animal |
| hemolymph | open circulatory system |
| hemocoel | blood cavity |
| bivalves | mollusks in the class Bivalvia whose shell is divided into 2 halves, connected by a hinge |
| adductor muscles | muscle attached to the inside surface of each valve, used to close the shell |
| siphons | fleshy tubes that allows water to enter and leave the bivalve |
| incurrent siphon | where water enters the bivalve |
| excurrent siphon | where water leaves the bivalve |
| cephalopods | members of the class Cephalopoda including octopuses, squids, cuttlefishes, and chambered nautiluses |
| chromatophores | pigment cells located in the outer layer of the mantle |
| annelid | phylum annelida, including colorful feather-duster worms, common earthworms, and bloodsucking leeches--the term means little rings, refering to the many body segments that make an annelid look like it is composed of many rings |
| setae | external bristles on annelids |
| parapodia | fleshy protrusions |
| esophagus | the tube area where food passes through on its way to the crop |
| crop | temporary storage area for food |
| gizzard | the thick muscular part of the gut |
| typhlosole | an infolding of the intestinal wall |
| aortic arches | five pairs of muscular tubes that link the dorsal and ventral blood vessels near the anterior end of the worm |
| nephridia | excretory tubes used by earthworms used to excrete cellular wastes and excess water |
| clitellum | a thickened section of the body that excretes mucus |
| seminal receptacle | a pouchlike place where sperm are stored |
| chitin | a tube made of mucus and tough carbohydrates |
| polychaeta | 2/3 of all annelids are members of the class polychaeta, polychaeta means many bristles which refers to the numerous setaethat help polychaetes move |
| hirudinea | smallest class of annelids consisting of about 300 species of leeches |
