CK12 Life Science

Types of Mollusks

WithinthephylumMollusca,thereareapproximately160,000livingspeciesandanestimated
70,000 extinct species. Mollusks are typically divided into ten classes, of which two are
extinct. Which classes are you most familiar with?

Table 12.1:Living Molluscan Classes

Molluscan Class Number of Species Habitat Features of

Class/Examples

Caudofoveata 70 Deep ocean Worm-like organ-

isms

Aplacophora 250 Deep ocean Worm-like organ-

isms

Polyplacophora 600 Rocky marine shore-

lines

Chitons (Figure

12.6)

Monoplacophora 11 Deep ocean Limpet-like organ-

isms

Gastropoda 150,000 (80% of liv-

ing molluscan diver-

sity)

Marine (some

limpets live in

deep ocean around

hot hydrothermal

vents), freshwater,

and terrestrial

Abalone, limpets,

conch, nudibranchs,

sea hares, sea but-

terfly, snails, and

slugs (Figure12.7.)

Cephalopoda 786 Marine Most neurologically

advanced of all in-

vertebrates; include

squid, octopus, cut-

tlefish, and nautilus

(Figure12.8).