Invertebrate Phylum Mollusca (Mollusks) Slide 2 Vocabulary
visceral mass =contains internal organs of digestion, excretion,
and reproduction mantle = thin membrane that surrounds internal
organs Slide 3 Vocabulary Radula = tongue-like structure with teeth
used to grate, cut, and scrape Torsion =visceral mass twists 180*
in relation to head Siphon = fleshy tubes for movement of water in
a mollusk Slide 4 Characteristics true coelm * bilateral symmetry *
two body openings * 3 body parts: head, muscular foot, visceral
mass * most have shell secreted by mantle * gills for gas exchange
with water * some have a radula for feeding Slide 5 Slide 6
Gastropoda: "stomach foot" * single shell - snails, abalone, conch
* no shell - nudibrachs, slugs * move by muscular contractions of
foot * open circulatory system Slide 7 Slide 8 Slide 9 Slide 10
Bivalvia: shell with "two valves * clams, oysters, scallops *
strong muscle for pulling shell and burrowing * no head or radula *
filter food from water via gills; cilia move food to stomach Slide
11 Cephalopoda: "head-foot * octopuses, squid, nautilus * free
swimming; predatory; tentacles with suckers * radula and sharp beak
* large brain and advanced nervous system * closed circulatory
system Slide 12 Slide 13
