MOLLUSCA BIO 104 Exam 3

Malacology

Study of molluscs

Molluscs animal phylum

110,000 species

Major seafood group

Examples of Molluscs

Whelks, Tulips, Olives, Augers

“Queen Conch”

“Oyster Drill”

“Pulmonates”

escargo - edible name for snails

Major Characteristics of Molluscs

Gastropoda “Snails and Slugs” “Stomach Foot”

Largest class of Molluscs (35,000 sp.)

Most eat green algae like and underwater cow

Alabama Freshwater Snail Diversity

43% of North American species are found in Alabama

175 species in Alabama

42 species now extinct

28 species of high concern

Cephalopoda “Squid/Octopi” “Head Foot”

Head and foot are attached to each other

Foot forms the arms and tentacles

Have two tentacles, twice as long used for grabbing and holding things

Mantle starts where head ends, body tube and the fin

Siphon used for a funnel/cone shaped structure used for swimming

Radula used for flesh eating

Valve takes the form of the pen

Pelecypoda or Bivalvia “Oysters, Clams, Scallops, Mussels” “Hatchet/Wedge/Foot/Axe”

Valve shape has perfect bilateral symmetry

ECOLOGICAL role as filter feeders, underwater vacuum cleaners

Radial used for raking water into the mouth

Economic Importance of Bivalves

Major food group

What part of scallops do you eat?

You eat the adductor muscle or the much tougher foot

What part of Clams/Mussels (clam chowder or oyster stew) do you eat?

All, everything but the shell

What part of Oysters do you eat (raw or fried)?

Can eat both but raw can be dangerous due to the bacteria they filter when they were alive

Why can raw Oysters sometimes be dangerous?

Sometimes they’ve been sitting out too long and are served to people with new bacteria growth on them. Also can be dangerous because of the bacteria they filter.

Oldest living animal

Quahog Clam - 507 years old

Alabama Freshwater Mussel Diversity

60% of North American Species found in Alabama (180 species)

More than any other state

Many endemic species

Many endangered species (70%)

Loligo “Bay Squid”

Most commonly eaten squid

Kalamari - edible name for squid

17 meter long Giant Squid!

Australian Blue-Ringed Octopus - most venomous

Octopus are the most intelligent of any invertebrae, can learn, recall, problem solve

Chambered Nautilus

External valve that looks like a coil/spring

Pearl Harvesting (Wild Pearls) Cultured Pearl Industry

How does a pearl form?

The mantle secrete the valve (shell). A grain of sand may get stuck between the valve and the mantle. Every time the mantle creates a layer of CaCo3. It makes a layer over the foreign object, creating a pearl, like scar tissue.

Color depends on the type of bivalve

Japanese and Australians