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31 terms

Biology Chapter 21 (pages 443-454)

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mollusks
soft-bodied, boneless water creatures
foot
used for locomotion
visceral hump
contains internal organs
mantle
a skinlike organ which covers the visceral hump, and in most species, produces a calcium carbonate shell for protection
pearl
when nacre builds up around an irritant
adductor muscles
the hinges that hold together the two shells of a bivalve mollusk
mantle cavity
open chamber in which the gills are located
incurrent siphon
takes water into the mantle cavity to the gills
excurrent siphon
where water that has passed through the incurrent siphon exits the body
gastropods
also called univalves - have a single shell
slugs
gastropods which look like snails without shells
nudibranches
sea creatures which have brilliant colors and elaborate plumelike gills
bivalves
two-shelled
radula
a rough, file-like organ in mouth that scrapes food and carries it like a conveyor belt into the digestive tract
giant squid
largest invertebrate
nautilus
only cephalopod with an external shell
echinoderms
spiny-skinned sea animals
watervascular system
a complex system of water-filled tubes that extends throughout the body
rays
the arms of starfish
eyespot
at the end of each starfish ray
tube feet
on the underside of starfish rays; appear in two double rows
rotifers
microscopic invertebrates found in freshwater lakes and ponds
parthenogenic
eggs that require no fertilization
cnidocytes
stinging cells
polyp
a cylindrical body type for coelenterates
medusa
a free-swimming, umbrella-shaped body type which has its mouth facing downwards
sea anemone
"flower" of the ocean
corals
colonial coelenterate
coral reefs
when limestone cups of many corals eventually form together into these limestone structures
excurrent pore
the opening by which water leaves a sponge
incurrent pores
the tiny openings by which water enters a sponge