Phylum Mollusca

• Most with bilateral symmetry
• Most with external shell
  • Some internal and reduced (vestigial)
  • Some lost all together
• Feeding device like a toothed, rasping tongue (radula)

Radula

• Muscular “foot”

This bivalve has the muscular foot sticking out of the shells

Cephalopods have a muscular foot modified into tentacles

snails and slugs are known as “belly-foot” animals

• Complete digestive tract with 2 ends

 

• Class Bivalve: Clams and their relatives
  • Filter feeders
  • 2 shells, strong muscles hold shells shut

• Class Gastropoda: snails and slugs
  • One shell (or reduced and internal)
  • Herbivores, carnivores and decomposers

Sea slugs

• Class Cephalopoda: squid, octopus, and nautilus
  • Distinct head, large eyes
  • Carnivorous
  • Crawl or use a jet stream of water to move

blue ringed octopus

Squid

nautalis

Cuttlefish

Gastropods eating other mollusks…

These round holes are a result of snails using their radula (rough, scraping tongue like structures) to  scrape through the shells of other snails and bivalves.

Continue to Arthropoda