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Invertebrates. Jellies – Phylum Cnidaria. Round Worms – Phylum Nematoda. Live in sediments or tissues of other organisms Over 12,000 described species (may be 500,000) Very abundant (hundreds per mL of sediment) Hydrostatic skeleton. Peanut Worms – Phylum Sipuncula.
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Round Worms – Phylum Nematoda • Live in sediments or tissues of other organisms • Over 12,000 described species (may be 500,000) • Very abundant (hundreds per mL of sediment) • Hydrostatic skeleton
Peanut Worms – Phylum Sipuncula • Unsegmented marine worms • Borrow in mud, corals or empty shells • Deposit feeders
Spoon Worms – Phylum Echiura • Exclusively marine, unsegmented • Non-retractable probiscis
Segmented Worms – Phylum Annelida • Segmented worms • Gut - coelom • Hydrostatic skeleton • Longitudinal and radial muscles • Efficient locomotion and burrowing • More than 15,000 species • Cosmopolitan
Segmented Worms – Phylum Annelida • Class Polychaeta
Segmented Worms – Phylum Annelida • Class Polychaeta • Diverse lifestyles • Free-living predators • Often well-developed eyes and sense organs, jaws
Segmented Worms – Phylum Annelida • Class Polychaeta • Diverse lifestyles • Burrowing deposit feeders • Burrowing suspension feeders
Segmented Worms – Phylum Annelida • Class Polychaeta • Diverse lifestyles • Burrowing deposit feeders • Burrowing suspension feeders
Phylum Mollusca • Body Structure
Phylum Mollusca • Radula
Phylum Mollusca • Reproduction Trocophore Veliger
Phylum Mollusca • Gastropods
Phylum Mollusca • Gastropods Petropods Nudibranchs with symbiotic algae
Phylum Mollusca • Bivalves • Laterally compressed • Two-valved shell • No head or radula • Gills used for suspension feeding (active) & respiration • Water enters and leaves through siphons • Some anchor to substrate with byssal threads