Invertebrates Dr. M. Diamond The Animal Kingdom Invertebrates Dr. M. Diamond

Porifera - Sponges Simplest animals Live in water (mostly marine) No organs No symmetry Have pores and central cavity Eat small floating organisms and debris Collar cells – filter and digest food particles Can regenerate

Cnidaria – Jellyfish and coral Cnida (Gk.) - lasso Jellyfish = medusae Coral = polyps Radial symmetry Long tentacles With nematocysts (stinging cells) Complex tissues Gut Simple nervous system

Platyhelminthes - Flatworms Planaria, flukes, tapeworms Bilateral symmetry Head Eyespots – sense light Sensory lobes on either side of head Nervous system

Nematoda - Roundworms Bilateral symmetry Simple nervous system Some are parasites

Mollusks – Snails, slugs, clams, squid, octopus Most live in ocean Some live on land or in fresh water Bilateral symmetry Foot Gills, gut and other organs Shell Circulatory system (open) More complex nervous system with brain

Annelids – Segmented worms Bilateral symmetry Earthworms, bristle worms and leeches Nearly identical body segments Closed circulatory system (like us) Nervous system Brain and nerve cord True body cavity

Arthropods – Insects, spiders, crustaceans Jointed limbs Exoskeleton Well-developed nervous system Specialized parts (wings, claws, antennae, etc.)

Echinoderms – Sea stars, sea urchins, sand dollars, etc. Internal skeleton Nervous system with simple eyes Water vascular system for movement Adults – radial symmetry Larva – bilateral symmetry