Phylum Mollusca

mantle

a thin layer of tissue that secretes the shell in gastropods. in cephalopods it is thick and muscular and covers the body

nudibranch

a sea snail. no shell

ink sac

glands in a cephalopod that secretes a dark fluid to confuse predators

adductor muscles

muscles that hold the shells of a bivalve shut

siphon or jet

in a cephalopod, water is forced out of this to propel them backwards

umbo

the bump at the top of a bivalve shell. the part of the shell that grows first

ctenidia

the specialized gills of a bivalve, used for filtering oxygen and particles of food from the water

byssal threads

sticky fibers on a mussel that allows it to stick to surfaces

cuttlebone

the modified internal shell of a cuttlefish. it helps with buoyancy

growth rings

rings on the outer surface of a bivalve shell. the age can be determined by these

spermatophore

a packet of sperm that the male cephalopod passes to a female using a modified arm

valve

this is what we call each shell of a bivalve

beak

the sharp jaws of an octopus or squid

chromatophore

the color changing cells of a cephalopod. allow them to camouflage

radula

the ribbon of teeth found in a gastropod. like sandpaper and used to scrape algae or flesh

foot

the means of locomotion in a gastropod. muscular

NACRE

the “mother of pearl” material that many species of bivalves secrete around irritants that get caught between the mantle and shell

chitin

the radula is composed of this strong material made from cellulose

incurrent/excurrent siphons

these allow water in and water out of the mantle cavity of a bivalve

pen

the modified internal shell of a squid. provides support

“head footed”

class cephalopoda

two valves connected by a hinge

class bivalvia

“stomach footed”

class gastropoda

nudibranchs, snails, slugs, limpets, abalone

class gastropoda

clams, scallops, mussels

class bivalvia

squid (internal shell), octopus (no shell), cuttlefish (internal shell), nautilus (external shell)

class cephalopoda