Section 21.1- Mollusks Flashcards
the largest group of water animals on Earth
mollusks
mollusks are distinguishable by
muscular FOOT
VISCERAL HUMP
MANTLE
contains internal organs
visceral hump
used for locomotion
foot
skinlike organ that covers the visceral hump and produces carbonate calcium shell for protection
mantle
the most familiar classes of mollusks
bivalves
gastropods (univalves)
cephalopods
two-shelled mollusks
clams, scallops, oysters, mussels
bivalves
edible clams, scallops, oysters, mussels are called
shellfish
each shell of a bivalve consists of________ distinct layers
three
the inner shell layer of some inedible oysters and clams is called
mother-of-pearl
the substance from which the pearly layer is formed in a clam or oyster is formed
nacre
the sheets of nacre build up around the irritant and eventually form a
pearl
hold together the two shells of a bivalve
the main parts of the scallops and muscles that are eaten
adductor muscles
a clam uses its foot for …
burrowing very quickly into the sand
scallops swim rapidly by
opening and closing shells
oysters are
sessile
one of the most critical activities for a bivalve is the movement of water into and out of its ____________
the open chamber in which gills are located
mantle cavity
the siphon in the mantle cavity that takes water into the mantle cavity to the gills
incurrent siphon
where oxygen and carbon dioxide are echanged in bivalves
gills
most of the water passes out of the mantle cavity and gills through the
excurrent siphon
a bivalve has an ____________ circulatory system
open
bivalves have a well-developed _______ system
nervous
reproduction in most bivalves is sexual, with ________________ fertilization
external
stomach-footed mollusks that are often called univalves because most of them have one shell
gastropods
when a gastropod’s shell spirals clockwise to open on the right
right-handed or dextral
a few univalve shells spiral counterclockwise and are said to be
left-handed or sinistral
T/F: All gastropods have shells
FALSE
gastropods that look like snails without shells
slugs
marine slugs that include some of the most beautiful and graceful sea creatures
nudibranchs
T/F: Univalves have a visceral hump, foot, and (usually) shell
TRUE
the gastropod’s belly rests on its
foot
a rough, filelike organ found in univalves that scrapes food and carries it like a conveyer belt into the digestice tract
radula
consists of octopus, squid, cuttlefish, and chambered nautilus
head-foot mollusks
cephalopods
a torpedo shaped cephalopod noted for its ability to move by “jet propulsion” by forcing water out of a siphon
squid
three categories of squids
common squid (large numbers in marine waters)
giant squid (found in temperate regions of ocean)
colossal squid (lives in the oceans around Antarctica)
the largest invertebrates
colossal squids
cephalopods have a ______________ circulatory system
CLOSED
cephalopod that has 8 arms which are studded with suction cups for catching prey
octopus
the most conspicuous part of the octopus is the
head
the only cephalopod with an external shell
nautilus
the angles of the chambers of a nautilus are mathematically precise and form what mathematicians call a
logarithmic spiral
cephalopod with poorest vision
nautilus
