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Echinoderms Chapter 29
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Echinoderms have unusual characteristics 1. Move by means of hundreds of hydraulic suction cup-tipped appendages 2. Have skin covered with tiny, jaw like pinchers 3. Live in salt water
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Internal skeletons Hard bumpy endoskeleton covered by thin epidermis Sea Urchins- Long pointed spines Starfish- Rays covered with Round spines Sea Cucumber Spiny skin consist of soft tissue Embedded resemble spines
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Advantages of Radial Symmetry Sense potential food, predators, & other environmental features from all directions
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Echinoderms can regenerate Regeneration: is the replacement or regrowth of missing body parts through cell division
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Body Plan of the Sea Star The ampulla is located on the opposite ends from the suction cup & has muscles that contract & relax Pedicellaria are pinchers located at the ends of the rays Ampullae Pedicellariae Ring canal
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Water Vascular System Water enters & leaves through the madreporite Works like a strainer to keep large particles out of the pipes Madreporite
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Rays From the mouth runs grooves of tube feet- hollow thin walled tubes that have suction cups on ends of rays Each tube foot works independently helping the animal move
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Tube Feet The underside of a sea star has tube feet that run along a groove on the underside of each ray.
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Feeding To eat, it pushes its stomach out of its mouth & spreads its stomach over the food
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Eyespot When moving the star fish curls up the tips of its rays so the eyespot are turned outward No Brain…have nerve nets
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Nutrition Starfish-carnivorous & prey on worms or mollusk –clams Sea Urchins- herbivores & graze on algae Brittle Star, Sea Lilies & Sea Cucumbers feed on dead & decaying matter called detritus
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Diversity of Echinoderms Group dates from Paleozoic Era Endoskeletons were fossilized consisting of more than 13,000 fossil species identified Approx 6,000 species still exist today
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Starfish-Class Name: Asteroidea Most have 5 rays but some can have more than 40 rays About ¼ of species belong to this class
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Brittle Star-Class Name: Ophiuroidea Extremely fragile (parts will fall off if you pick it up) Adaptation to survive an attack by predator— regeneration New ray grows in a few weeks Moves like a snake—pass food to mouth by tube feet
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Sea Urchins & Sand Dollars: Echinoidea Globe—disk shaped covered with spines Do not have rays Live sand dollar have hair-lose when they die Sea Urchins inhabit rocky areas-look like pin cushions
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ARMY OF SEA URCHINS https://www.youtube.com/watch?v=D3W4OCnHyCs
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This shell is one of the most unusual of all marine life. The five slits on the edge represent the five wounds in the Body of Christ. There is an Easter Lily design in the center of the top, with a five pointed star in it's center, Star of Bethlehem. On the back is an outline of the Poinsettia, the Christmas flower. When the shell is broken open, five small but perfect replicas of a dove will be found, Doves of Peace. The Legend of the Sand Dollar
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Sea Cucumber-Class Name: Holothuroidea Use tentacles & tube feet for locomotion When threatened, they may expel a sticky mass of tubes through the anus or rupture releasing some internal organs—will regenerate
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Sea Cucumber Protection
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https://www.youtube.com/watc h?v=aCxKFc3XtJs
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Sea Cucumber http://www.youtube.com/watch?v=wXf_Yo dWw40 http://www.youtube.com/watch?v=wXf_Yo dWw40
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Sea Lilies & Feather Stars Crinoidea Resembles plants Sea Lilies are the only sessile echinoderm Feather Star
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Chordates Section 2
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Phylum Chordates All have notochords: -Chordata means long, rod-like structure called notochord -Develops into a backbone during embryo stage
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Nerve Cord Have nerve cord: -dorsal nerve cord- bundle of nerves that lies above the notochord In adults posterior portions develop into spinal cord
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Have Gill Slits & Muscle Blocks Gill pouches are paired located in the pharynx behind the mouth As adults, use to strain food from the water Consist of stacked muscle layers called muscle blocks Can see Aids in movement of the tail
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Notochord Dorsal hollow nerve cord Mouth Pharyngeal pouches Muscle blocks AnusPostanal tail Body Plan
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Sea Squirts Also called tunicates 1250 species that live in the ocean Most adults sessile If you remove one from its colony-it might squirt out a jet of water
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Lancelets Small streamlined, marine animal-usually 5 cm long Spends most of their time buried in the sand with only their heads sticking out Filter feeders
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