2. Anatomy
• Two shells (valves)
held together tightly
by adductor muscles
• No head, brain is a set
of nerve cells (ganglia)
• Gills to take oxygen
from water
• Mantle secretes the
shell
• Bilateral symmetry
3. Class Bivalvia – The Bivalves
(clams, mussesls, scallops, oysters)
4. Habitat
• Benthic
– Most Sessile, few motile
– Infauna – most burrow
down
– Epifauna – some live on
seafloor
• Mussels attach with
byssal threads
• Scallops swim by
clapping shells together
7. Pearl Formation
• Mostly in oysters
• Protection against
parasites or grains
of sand
• Often not round
• Natural pearls are
more costly
• Cultured pearls are
made by inserting
an object in the
oyster
