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Phylum Mollusca from the Latin mollis meaning soft

Phylum Mollusca from the Latin mollis meaning soft. Basic Features of Molluscs Bilaterally symmetrical Coelomate Protostomic vs. deuterostomic . Complete cephalization Number of species ranges from hundreds to thousands combined Soft body and muscular foot.

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Phylum Mollusca from the Latin mollis meaning soft

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  1. Phylum Mollusca from the Latin mollis meaning soft

  2. Basic Features of Molluscs • Bilaterally symmetrical • Coelomate • Protostomic vs. deuterostomic. • Complete cephalization • Number of species ranges from hundreds to thousands combined • Soft body and muscular foot

  3. Molluscan Ecology • The majority of mollusks are marine • Large numbers of species occupy freshwater • Terrestrial habitats • Herbivores, Predators, Prey for sea otters

  4. Molluscan Taxonomy (primitive to most complex) • Class Polyplacophora- Chitons • Class Gastropoda- Snails, abalone, and slugs • Class Bivalvia- Clams, and scallops • Class Cephalopoda-Octopi and squids

  5. Molluscan Morphology • They also have gills, a mouth and an anus • Rasping organ called a radula • A sheath of tissue called the mantle that covers the body and can secrete the shell (if there is one) .Visceral mass which contains most of the organs. • A mantle cavity that houses the gills or lungs • A calcium shell present in most molluscs: some molluscs have greatly reduced their shells, e.g., squid; while others have completely lost it, e.g., slugs, nudibranchs, and octopus *Shape of Life 1

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  7. Class Polyplacophora • entirely of marine species • 8 transverse, overlapping shell plates or valves • Feed on small particles of algae

  8. Class Gastropoda (Univalvia) • A univalve, generally spirally coiled SHELL is present in the majority of gastropods Shell coiling in gastropods *Another characteristic feature of the majority of gastropods is that the ancestral conical shell has now become coiled. TORSION

  9. Class Bivalvia • single shell composed of two valves • The two valves of the shell are hinged dorsally

  10. Class Cephalopoda *Shape of Life 3 • Squids and cuttlefish have 10 appendages comprised of 8 arms and 2 long tentacles possessing numerous cup-shaped, rimmed suckers. • tentacles are used to capture prey • suckers pull food materials towards the mouth.

  11. 2.The octopuses have eight long tentacles (sometimes called arms) each with a row of suckers on the inner surface. *Shape of Life 4

  12. 3. In Nautilus, the tentacles are much more numerous; there may be up to 90 in two concentric circles around the head. *Shape of Life 2

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