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Phylum Echinodermata. Greek “ echinos ” spiny “derma” skin. Main Characteristics. Radial symmetry: PENTARADIAL Bilateral in free swimming embryonic stages. Skeleton . endoskeleton made of tiny calcareous plates and spines (OSSICLES) Acts like exoskeleton but it’s NOT!
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Main Characteristics • Radial symmetry: PENTARADIAL • Bilateral in free swimming embryonic stages
Skeleton • endoskeleton made of tiny calcareous plates and spines (OSSICLES) • Acts like exoskeleton but it’s NOT! • always contained within a layer of living tissue • Mutable Connective Tissue (MCT) :has ability to be converted from stiff to soft in an instant
Water Vascular System • Hydraulic network of fluid-filled canals • Water enters the MADREPORITE • Very powerful, but slow • Gas exchange • Feeding • Locomotion
Respiration • Bumps and spines let in oxygen • Skin is very thin: oxygen can diffuse in from the surrounding water
Decentralized Nervous System • No brain • Nerve ring surrounding the gut • Radial nerves run under the ambulacrum
Reproduction • External Fertilization • Separate sexes • Reproductive organs in each arm • 100,000,000 eggs at once http://video.nationalgeographic.com/video/player/animals/invertebrates-animals/other-invertebrates/sea_urchin_breeding.html
Asexual Reproduction • Fission of body parts • Regeneration: spines, arms, intestines
ASTEROIDEA CRINOIDEA ECHINODERMS ECHINOIDEA OPHIUROIDEA HOLOTHUROIDEA
Classification • Kingdom Animalia • Phylum Echinodermata • Class Asteroidea • Class Echinoidea • Class Holothuroidea • Class Ophiuroidea • Class Crinoidea
Asteroidea “SEA STARS” • Mostly benthic carnivores • Eye spots: end of each arm. • Tube feet have suckers, which chemically adhere to the substrate. Another chemical bond is secreted to release the tube feet.
Pedicellariae- • Keep animal free from encrusting organisms • May contain toxins • Protect the papulae: skin gills
Feeding • Evert stomach and secrete primary enzymes on the prey. • The digestive juices break down the tissue of the prey, which the asteroids then suck up. • http://www.pbs.org/kcet/shapeoflife/episodes/ulti_explo2.html
Echinoidea “SEA URCHINS & SAND DOLLARS” • Ossicles overlap and are fused into test • Urchins also have pedicellariae
Feeding • Grazers: algae • Powerful chewing apparatus called the Aristotle's lantern- five jaws • http://www.biology.ualberta.ca/facilities/multimedia/uploads/zoology/Aristotle.swf
http://video.nationalgeographic.com/video/player/animals/invertebrates-animals/other-invertebrates/sea_urchin_breeding.htmlhttp://video.nationalgeographic.com/video/player/animals/invertebrates-animals/other-invertebrates/sea_urchin_breeding.html
Holothiuroidea “SEA CUCUMBERS” • Branching tentacles surround the mouth • Respiratory trees near anus • Suspension/deposit feeders • They cycle up to 90% benthic biomass in ocean • Defense: skin secretes toxins and they can expel organs (autotomicevisceration) • http://video.nationalgeographic.com/video/player/kids/animals-pets-kids/invertebrates-kids/sea-cucumber-kids.html
Ophiuroidea “ BRITTLE & BASKET STARS” • Move quickly moving arms • Arms are long, slender, and flexible • Ability to autotomize: spontaneous casting of limb • No suckers on tube feet-some have mucus to help them stick to things and capture prey • Five jaws • http://www.youtube.com/watch?v=muXV0Sax8JU • http://www.youtube.com/watch?v=-SiNJ1T3Xbs
Crinoidea “FEATHER STARS & SEA LILIES” • Most live in deep sea • Feather Stars: some are free swimming • Sea Lillies: most are sessile- only attached suspension-feeding echinoderms • Cirri used to attach or grab substrate • Brood their young • http://video.google.com/videosearch?hl=en&safe=off&client=firefox-a&rls=org.mozilla:en-US:official&hs=So9&q=feather%20star&um=1&ie=UTF-8&sa=N&tab=wv#
Feeding • Filter Feeders (mostly deep sea OM) • Cirri used to attach or grab substrate