Invertebrates

Jellies – Phylum Cnidaria

Round Worms – Phylum Nematoda

• Live in sediments or tissues of other organismsLive in sediments or tissues of other organisms

• Over 12,000 described species (may be 500,000)Over 12,000 described species (may be 500,000)

• Very abundant (hundreds per mL of sediment)Very abundant (hundreds per mL of sediment)

• Hydrostatic skeletonHydrostatic skeleton

Peanut Worms – Phylum Sipuncula

• Unsegmented marine wormsUnsegmented marine worms

• Borrow in mud, corals or empty shellsBorrow in mud, corals or empty shells

• Deposit feedersDeposit feeders

Peanut Worms – Phylum Sipuncula

Spoon Worms – Phylum Echiura

• Exclusively marine, unsegmentedExclusively marine, unsegmented

• Non-retractable probiscisNon-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 Annelida1. Class PolychaetaClass Polychaeta

Segmented Worms – Phylum Annelida1. Class PolychaetaClass Polychaeta

• Diverse lifestyles• Free-living predators

• Often well-developed eyes and sense organs, jaws

Segmented Worms – Phylum Annelida1. Class PolychaetaClass Polychaeta

• Diverse lifestyles• Burrowing deposit feeders• Burrowing suspension feeders

Segmented Worms – Phylum Annelida1. Class PolychaetaClass Polychaeta

• Diverse lifestyles• Burrowing deposit feeders• Burrowing suspension feeders

Phylum Mollusca

Phylum MolluscaA.A. Body StructureBody Structure

Phylum Mollusca• RadulaRadula

Phylum Mollusca• ReproductionReproduction

Trocophore Trocophore VeligerVeliger

Phylum Mollusca1.1. GastropodsGastropods

Phylum Mollusca1.1. GastropodsGastropods

Nudibranchs withsymbiotic algae

Petropods

Phylum Mollusca2.2. BivalvesBivalves• 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