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The GastropodsPhylum Mollusca
Class Gastropoda – “Stomach Foot”
-Extremely diverse and numerous group of animals-Many are snails, but there are species without shells or without coiled shells
Examples:• Whelk – can be large, predators• Conch – can be large, wind instruments• Periwinkle – very common snail in our area• Nudibranchs – no external shell (interior one
made of protein)• Limpets – not coiled like most snails; conical
or relatively flat• Slipper Snail – can change from male to female• Abalone – used for jewelry
Anatomy• Most have a spiraling shell
surrounding a soft bodied animal
• Well defined head, ganglia, no hearing
• Excellent sense of smell/taste
• Gills to take oxygen from water
• Trap door (operculum) to protect animal when withdrawn in its shell
• Mantle secretes the shell• Bilateral symmetry
Habitat• Benthic– Motile– Epifauna –live on
seafloor– Have adapted to
almost every marine environment in the world (i.e., rocks, sand, mud, etc.)
Feeding-Most are scavengers using radula to scrape algae off rocks or decaying animal matter from the bottom-Some are predators
Ex: cone snailhttp://www.youtube.com/watch?v=zcBmMPJrrKk
Feeding cont.Some of predatory snails feed by drilling a hole in another MolluskExamples: moon snail, oyster drill
Radula in Action
Gastropod Reproduction
-Separate sexes-External fertilization and development-Distinct egg cases
Nudibranchs - Sea Slugs• Most brightly
colored to ward off predators
• Many have little outgrowths that are part of their respiratory system