Marine Invertebrates (Ch.9) part 3 Echinoderms Invert chordates CAT Review Game BINGO
Ph. Echinodermata (sea stars, sea urchins)
Ph. Echinodermata (sea stars, sea urchins) Have spiny skin Water vascular system (for movement, feeding, gas exchange) = network of water-filled canals, branch into extensions called tube feet Radial symmetry in adults (larvae have bilat) Capable of regeneration Sea stars are carnivorous, urchins are More closely related to Mostly Benthic
Ph. Echinodermata (sea stars, sea urchins)
Echinoderm tube feet Video
Echinoderm Structure Endoskeleton: internal skeleton that lies just beneath the epidermis : plates of calcium carbonate endoskeleton is composed of ossicles held together by connective tissue Spines and tubercles project outward from the ossicles pedicellariae: tiny, pincer-like structures around the bases of spines that keep the body surface clean in some echinoderms
Echinoderm Structure Water vascular system: unique hydraulic system that functions in locomotion, feeding, gas exchange and excretion water enters by the passes through a system of canals attached to some canals are tube feet hollow structures with a sac-like ampulla within the body
Sea Stars Class Typically composed of a central disk + 5 arms or rays On underside, ambulacral grooves with tube feet radiate from the mouth along each ray Aboral surface: the side opposite the mouth, which is frequently rough or spiny
Sea Stars Feeding in sea stars most are carnivores or scavengers of and sometimes fish prey are located by sensing of substances they release into the water sea stars envelope and open bivalves, evert a portion of the stomach, and insert it into the bivalves to digest them
Ophiuroids Class Ophiuroidea e.g. brittle, basket and serpent stars Benthic with 5 slender, distinct arms, frequently covered with many spines Lack Tube feet lack suckers and are used in locomotion and feeding Brittle stars shed arms if disturbed
Ophiuroids Feeding in ophiuroids: carnivores, scavengers, deposit feeders, suspension feeders, or filter feeders able to cast off one or more arms when disturbed or seized by a predator
Sea Urchins and their Relatives Class Echinoidea ( like a hedgehog ) echinoids Body enclosed by a hard exoskeleton Benthic on solid surfaces (sea urchins) or in sand (heart urchins, sand dollars) Regular (radial) echinoids: sea urchins; spheroid body with long, moveable spines Irregular (bilateral) echinoids: heart urchins and sand dollars; have short spines on their tests
Sea Urchins and their Relatives Feeding mostly grazers which scrape algae and other food materials from surfaces mouth contains of 5 teeth -chewing structure irregular urchins are selective deposit feeders some sand dollars are suspension feeders
Sea Cucumbers Class Holothuroidea Have elongated bodies, and usually lie on 1 side Respiratory trees: a system of tubules located in the body cavity for Sexes are generally separate
Sea Cucumbers Feeding in sea cucumbers mainly deposit or suspension feeders oral tentacles: modified tube feet coated with mucus which are used to trap small food particles Defensive behavior can i.e., release some internal organs through the anus or mouth
Crinoids Class Crinoidea Primitive, flower-like echinoderms Most are feather stars, which seldom move and cling to the bottom with grasping Suspension feeders Can regenerate lost arms
Ecological Roles of Echinoderms Spiny skins Predators of molluscs, other echinoderms, cnidarians, crustaceans crown-of-thorns sea star eats coral sea urchins destroy kelp forests Black sea urchins (Diadema antillarum) control algal growth on coral reefs Sea cucumber poison, holothurin, has potential as a