| A | B |
|---|
| Trochopore | The larval form of a mollusk. |
| Head-foot | A head that contains sensory organs and a mouth. Also, a large muscular organ used for locomotion. |
| Visceral mass | Contains the heart, organs of digestion, excretion, and reproduction. |
| Mantle | A layer of epidermis that covers the visceral mass. |
| Mantle cavity | A space between the mantle and the visceral mass. |
| Ganglia | Paired clusters of nerve cells. |
| Gastropods | The largest and most diverse class of mollusks. Ex. snails. |
| Torsion | The visceral mass twists around 180 degrees in relation to the head. It is used mostly as a defense mechanism. |
| Hemolymph | Circulatory fluid found in gastropods. |
| Hemocoel | Blood cavity filled with hemolymph. |
| Bivalves | Mollusks whose shell is divided into two parts. Ex. clams, oysters, and scallops. |
| Adductor muscles | Powerful muscles that are attached to the inside surface of each valve. |
| Siphons | Hollow fleshy tubes found in clams. |
| Incurrent siphon | How water enters a clam through the action of cilia. |
| Excurrent siphon | How water leaves a clam. |
| Cephalopods | Mollusks that include octopuses, squids, cuttlefishes, and chambered nautiluses. |
| Chromatophores | Pigment cells that can produce a sudden change of in the color of cephalopod, allowing the animal to blend in with its surroundings. |
| Setae | External bristles used to classify and for locomotion. |
| Parapodia | Fleshy protrusions used to classify and for locomotion. |
| Esophagus | A tube that leads from the mouth to the crop. |
| Crop | A temporary storage area for food in annelids. |
| Gizzard | A muscular part of the gut in annelids. |
| Typhlosole | An infolding of the intestinal wall that increases the surface area available for digestion and absorption. |
| Aortic arches | Five pairs of of muscular tubes that link the dorsal and ventral blood vessels. |
| Nephridia | Excretory tubules used to eliminate cellular wastes and excess water. |
| Clitellum | A thickened section of the body. |
| Seminal recepticle | A storage space for sperm from another worm. |
| Chitin | A tough carbohydate used to create a tube that will unite the sperm with the eggs in a worm. |
