phylum echinodermata lauren and simon. general information echinoderms– echin (spiny) and derma...

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  • Phylum EchinodermataLauren and Simon

  • GENERAL INFORMATIONEchinoderms echin (spiny) and derma (skin)

  • SymmetrySecondary Radial Symmetry the larvae are bilateral and the adults are radial

  • Water Vascular SystemDistinctive aspect to echinoderms

    This is what echinoderms use in order to move, do respiration, and transport food and waste. It a system that consists of canals connected to tube feet (tubular projections like in the arms of a starfish) and it uses hydraulic pressure in order to operateAt the base of the foot there is a sac called the ampulla that holds fluid. When it contracts, water shoots down the foot and extends it.The white parts are where the tube feet are in this sea urchin

  • Body DevelopmentThe Echinodermata has a two stage developmentthe larvae and the adult. When the larvae grows, its left side then grows a lot, and the right side gets absorbed. The left side then grows in a 5 part radial symmetrical fashion, creating the adult echinodermata.

  • Germ LayersTriploblastic

  • Basket StarBrittle StarGametes put into water in bursal sacsBecomes a larva after fertilization and undergoes metamorphasis without attachmentReproductionExamples

  • Unique AbilitiesEchinoderms have a special kind of tissue connected to ossicles (plates made of calcium carbonate) that can change their consistency from solid to liquid very quickly. This phenomenon allows echinoderms to do amazing things:Sea urchins can move or lock their spinesBrittle and sea stars can bend or purposely break off an armSea cucumbers can move/flow into narrow places and harden when it is in a safe place


  • Asteroidea (Sea Stars)Mostly eat clams and oysters or other animal that is too slow to defend itselfIt slowly pries open its prey in order to eat it, sending out its stomach to consume the body of the shellfishThey have two stomachsone is used to eat and the other is used for digestionLike all echinoderms, it has a complex nervous system, but no brainThey have eyespots that are light sensitiveThey have other sensory perception such as touchUnlike the brittle star, sea stars organs enter their arms.They can break off their arms and the arms can regenerate

  • Holothuroidea (Sea Cucumber)Sea cucumbers are scavengers, looking for food at the bottom of the oceanThey usually live in tropical reefsIf it is threatened, it will stiffen and a jet of water will shoot out of one endIf they feel threatened, they can also throw out their internal organs to distract predators, then grow new organsSea cucumbers can form dense populationsThey can grow up to 16 inchesThey use their tube feet to move very slowly

  • Echinoidea (Sea Urchin and Sand Dollars)The pores in a sand dollar allow water to enter its Water vascular system, allowing it to moveSand dollars usually live together at the bottom of the oceanSand dollars become bleached and loose their spines when left out in the sun on the beach, so the ones in the store are very different from live onesSea urchins have teeth made of calcium carbonate, and the entire chewing organ is called Aristotle's LanternSea urchins mainly eat algae, but can also eat other invertebrates like mussels, sponges, and brittle starsSea urchins spines protect it from predators, but it is not clear whether the spines or the pedicelleriae (appendages used to keep encrusting organisms off) between the spines are venomous

  • CrinoideaRays collect foodPinnules increase surface areaCalyx contains most of the organsFilter feeders tube feet move particles down the ambulacral grooveSaccule excretes

    Inner structure of a ray

    in the calyx

  • Sea lilies were once thought to be planted in the ground but researchers found out that they actually can crawl from danger at 5 cm/s. They use their leg-like petals to crawl along the ocean floor. They use a lizard-like technique and leave their roots behind when escaping predators. Star Sea Lily

  • OphiuroideaPentaradial symmetryCalcium Carbonate skeletonWater vascular system that ends with tube feetLong and nearly solid rays which move like snakesArms can regenerateCarnivores, filter feeders, and scavengers

    Five jaws10 bursae are used for excretionCoelem is smaller than other echinodermsNo eyesEpidermis is sensitive to light and other stimuli


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