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Phyla Annelida/Mollusca Comparison. Mollusca. Annelida. Mollusca. Annelida. Coelomate 3 germ layers Closed circulatory system All organ systems Sexual reproduction Filter feeders to predators. Pharynx Setae Hermaphodites Gizzard Crop Segmentation. Mantle Radula
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Mollusca Annelida
Mollusca Annelida Coelomate 3 germ layers Closed circulatory system All organ systems Sexual reproduction Filter feeders to predators Pharynx Setae Hermaphodites Gizzard Crop Segmentation Mantle Radula Open circulatory system Gills or Lungs
Phylum Molluska: Soft Bodied
Summary of phyla characteristics • Where do they live: • oceans • terrestrial • fresh water • What kind of symmetry do they have? • Bilateral
Summary of phyla characteristics • List the 3 classes and then give examples of each • Cephalopoda • Squid, octopus, nautilus • Bivalvia • Clams, mussels, scallops, and oysters • Gastropoda • snails, slugs, nudibranchs, abalones, and conches.
Body plan/tissue description • Are bilateral, have 3 tissue layers, and a coelom • All organ systems • Gills or Lungs for respiration • Have a soft body • Have a mantle, radula and a large ventral foot • Most – but not all – mollusks have an open circulatory system. • Most have a shell
How does it reproduce • All mollusks reproduce sexually. • External fertilization, as in clams and many snails. • Internal fertilization, as in squids and some snails. • Hermaphrodites are rare but occurs in few mollusks.
How does it get nutrients • Most sessile and slow-moving mollusks are filter-feeders (clams) • Some are herbivores (snails & slugs) with special mouthparts (radula) to gather vegetation or algae. • Predatory mollusks (squids and octopuses) use their beak-like jaws to capture prey; some produce venom.
Important vocab • Mantle - fold of skin that surrounds the organs. • Shell - structure in mollusks made by glands in the mantle that secrete calcium carbonate • Radula - tongue-shaped structure used for feeding by snails and slugs • Foot - used for locomotion • Open circulatory system - The blood flows out of the vessels and bathes the body organs. • Siphon - tubelike structure through which water enters and leaves a mollusk's body