Invertebrates Chapter 28

Sponges (Phylum Porifera) Body is made of pores that water enters through. Has a large opening where water leaves. Sponges are sessile (cannot move) The lining of the internal cavity is made of collar cells that act as sieves to trap plankton and other food

Sponges (Phylum Porifera) Sponges have a skeleton made of spicules. A spicule is made of silica or calcium carbonate. Can reproduce both sexually or asexually. Asexual – pieces of sponges can regenerate Sexual – (most are hermaphrodites) Sperm cells from one sponge enter another through pores.

Cnidarians Body forms: Medusa – free-floating, and umbrella-shaped Polyp – tube like and attached to something There are tentacles around the opening of the gastrovascular cavity. They have stinging cells with a barbed harpoon used for defense and to spear their prey

Cnidarians Examples: Hydras Jellyfish – sting prey with tentacles (some have toxins) Sea anemones – polyp form, feed on fish, reproduce asexually Corals – live in reefs, tough skeleton of calcium carbonate

Phylum Platyhelminthes (Flatworms) Can be parasitic Include: Marine flatworms Tapeworms – parasitic, attach to host’s intestines. Grow producing proglottids (rectangular body sections) Parasitic flukes – have suckers to attach to host

Phylum Nematoda (Roundwoms) Have a body cavity called pseudocoelom (fluid moved within this cavity) One way digestive system Some are parasites you find in dogs, others are free living hunters Human parasites include: Ascaris lumbricoides Trichinella spiralis Necator

Phylum Molluska Includes: Snails Slugs Oysters Clams Scallops Octopuses Squids Found in marine, freshwater and terrestrial habitats

Phylum Molluska Characteristics: Bilateral symmetry Foot – used for movement Mantle – forms the outer layer of the body Most have one or two shells Radula – tongue-like organ found in the mouth

Phylum Molluska Most species have male and female individuals. Some, though, are hermaphrodites (some species of slugs and snails) Oysters and sea slugs can change from one sex to the other and back again

Phylum Molluska Gastropods Snails and sea slugs Most have a single shell and a pair of tentacles on their head with eyes at the tip Can secrete mucus from their foot to glide along Can be herbivores or predators

Phylum Molluska Bivalves Most marine, some freshwater Clams, oysters, scallops, mussels Two-part hinged shell Some use jet propulsion to move quickly Most are filter feeders

Phylum Molluska Cephalopods Squid, octopuses, cuttlefish and nautiluses Body is made of a large head attached to tentacles Tentacles have suction cups or hooks to catch prey Most intelligent invertebrate Some have color vision Move via jet propulsion Marine predators, feeding on fish, mollusks, crustaceans and worms

Phylum Annelida (Segmented worms) Marine worms, earthworms, leaches Have a primitive brain in an anterior segement Have specialized organ systems Bristles called setae on each segment

Phylum Arthropoda Named after their jointed appendages. Includes: insects, spiders, scorpions, crustaceans Segmented Exoskeleton (the crunch you hear when you squish them)

Phylum Arthropoda Arachnids Spiders, scorpions, ticks, mites Most are carnivores, inject their prey with enzymes to dissolve tissue

Phylum Arthropoda Insects Ants, mosquitoes, flies, bees, crickets Largest group of organisms Head, thorax, abdomen

Phylum Arthropoda Crustaceans Crabs, lobsters, crayfish, shrimp, barnacles, water fleas and pill bugs Major food source for humans Barnacles are sessile as adults and they have hard plates used for protection. They are also hermaphrodites but typically don’t fertilize their own eggs

Phylum Echinodermata Spiny invertebrates that live on the ocean floor Sea stars, brittle stars, sea urchins, sea cucumbers Endoskeleton make of calcium Radial symmetry Water-vascular system – tubes filled with water connected to hallow tube feet

Phylum Echinodermata Sea stars – carnivores Brittle stars – thin, branched arms for movement Sea lilies and feather stars – very old, mouth located on the upper surface

Phylum Echinodermata Sea urchins and Sand dollars – spines for protection, sometimes venom Sea cucumbers – soft, no arms. Some are hermaphrodites. They trap food in the water with tentacles Sea daisies – no arms

Invertebrate Chordate Skeleton is completely internal. A rod called the notochord develops along the back of the embryo Pharyngeal pouches – later develop into gills in aquatic animals

Invertebrate Chordates Tunicates – adults are sessile, hermaphrodites Lancelets – found in shallow ocean water. Draw water through their mouth with cilia