Adapted in various ways for locomotion in gastropods, tentacles in cephalopods, burrowing in bivalves
Mantle
A thin tissue layer that covers the soft body and secretes the shell in some species
The mantle cavity, located between the mantle and the body, houses the gills (if present) and serves as a chamber for respiration, excretion, and reproduction
Visceral mass
Internal organs, arranged in various ways within the body
Coelom is reduced to open space surrounding heart and gonads
Radula
Many mollusks possess a specialized feeding structure
A rasping, tongue-like organ covered in rows of small teeth
Used for scraping, tearing, or drilling food, depending on the species' diet
Circulation
Open (except in cephalopods)
Blood is released directly into organs and body cavities (hemocoel)
No clear distinction between blood and interstitial fluid - blood is known as hemolymph
Hemolymph contains hemocyanin to transport oxygen; appears blue when exposed to air
