Phylum Echinodermata - MHHS 2016-2017 - Phylum Echinodermata •“spiny skinned” or “hedgehog skin” •sea stars (starfish), ... locomotion (most mobile echinoderm!)

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<ul><li><p>Echinoderms Phylum Echinodermata </p></li><li><p> spiny skinned or hedgehog skin </p><p> sea stars (starfish), sea urchins, sea cucumbers </p><p> 6000 species </p><p> radial symmetry in 2o development </p><p> bilateral symmetry in larva </p></li><li><p> </p></li><li><p> most have pentamerous radial symmetry = based on 5 parts </p><p> live on ocean bottom slow bottom crawlers </p><p> have no head </p><p> no anterior or posterior side oral </p><p>and aboral </p><p> complete digestive tract </p><p> internal endoskeleton secreted w/in tissues may be covered by a thin layer of ciliated tissues </p></li><li><p>Digestion mostly carnivorous </p><p> feeds by extending/everting part of stomach inside out thru mouth secreting digestive enzymes carries food back into mouth </p><p> guts may be very short (starfish or sea cucumber) or very long (sea urchins) </p><p> longer guts are needed to digest plant particles </p><p> nutrients are transported in fluid called coelemic fluid in the coelem </p></li><li><p>Circulatory system/gas exchange </p><p> O2 is transported via coelemic fluid </p><p> Lacks a true circulatory system </p><p> Gas exchange occurs in small, branched projections of the body wall connected to coelemic cavity </p><p> Sea cucumbers have respiratory trees pair of thin branched tubes </p><p>that are extensions of gut and are suspended in coelem by coelemic fluid they draw in water and </p><p>provide increased surface area for gas exchange </p></li><li><p>Nervous system </p><p> have a nerve net </p><p> coordinates tube feet and spine mvmt. </p><p> no brain </p></li><li><p>Reproduction </p><p> dioecious </p><p> may have 5-10 gonads located in body cavity </p><p> all species spawn at once to better insure fertilization in which eggs and sperm are simply released into water </p><p> fertilized egg develops into plankton as a ciliated larva (bilaterally symm.) </p><p> asexual reproduction by regeneration ability to grow back lost/damaged parts </p></li><li><p>Class Asteroidea </p><p> Sea stars, a.k.a. starfish </p><p> 5 arms radiating from a central disk with eyespot at each end that is sensitive to light </p><p> hundreds of tube feet with suckers protrude from oral surface along ambulacral groove </p><p> move in any direction very slowly </p></li><li><p>Class Asteroidea </p><p> have pedicellariae = modified spines that are pincer-like organs used to clean the surface </p><p> have a water vascular system use as others use muscles </p><p> predators of bivalves, snails, barnacles, other slow moving animals </p><p> Ex. Asterias </p></li><li><p>Class Ophiuroidea </p><p> Brittle stars </p><p> 2000 species </p><p> very long and flexible arms </p><p> arms move in snake-like motion for locomotion (most mobile echinoderm!) </p><p> tube feet have no suckers and are used for feeding </p><p> feed on organic matter and small animals picked up from the bottom (most are scavengers) </p></li><li><p>Class Ophiuroidea food is picked up by tube feet and </p><p>passed to the mouth </p><p> hide under rocks, coral, or cover up with mud/sand (dont like light!) </p><p> ex. spiny brittle star Ophiothrix angulata found subtidally from Chesapeake Bay to Florida </p><p> Ophioderma brevisipina lives in shallow water from Cape Cod to Florida </p></li><li><p>Class Echinoidea </p><p> Sea urchins and sand dollars </p><p> 900 species </p><p> endoskeleton forms a rigid test w/ movable spines and pedicullariae </p><p> possess a water vascular system </p><p> move by spines jointed to sockets in the test and suckers at the tip of each tube foot </p><p> 5 rows of ambulacral grooves w/ tube feet extending from pole to pole w/ mouth on the bottom and anus on top </p></li><li><p>Class Echinoidea System of jaw &amp; muscles called </p><p>Aristotles lantern used for biting off algae </p><p> omnivores </p><p> graze on attached or drifting plant material </p><p> ingest encrusting animals (like sponges and bryozoans) and dead organic material </p><p> very common on rocky shores </p><p> when it dies, it leaves behind the test ex. Eucidarias tribuloides - Carolinas to Florida very </p><p>thick and blunt </p><p> ex. Mellita quinquiesperforta - sand dollars found from Cape Hatteras (NC) to Florida yellow-brown in color bring food to mouth as they walk - small particles of food are chewed by dentary apparations - rattles when skeleton is shaken eaten by sea stars, flounder and cod </p></li><li><p>Class Holothiuroidea </p><p> Sea cucumbers </p><p> worm-like no spines - no radial symmetry </p><p> usually lies on one side w/ mouth at one end and anus at the other </p><p> endoskeleton has microscopic calcareous spicules throughout warty skin </p><p> have 5 rows of tube feet extending from mouth to anus </p><p> are deposit feeders </p></li><li><p>Class Holothiuroidea </p><p> tube feet around mouth are branched tentacles that pick up organic matter </p><p> may secrete toxic chemicals or discharge sticky filaments thru anus as defense </p><p> may expel gut and internal organs thru the mouth/anus = evisceration (extending the gut to distract the offender) sea cucumber regrows any lost parts w/in 6 wks. messy but effective </p></li><li><p>Class Holothiuroidea </p><p> ex. Leptosynapta snot sea cucumber no tube feet located all over the whole coast consumes detritus as it burrows </p><p> ex. Sclerodactyla briareus hairy sea cucumber - Cape Cod to Gulf of Mexico covered by slender tube feet </p><p> Japanese cook in soy sauce and ginger in China dry it and is a gourmet delicacy </p></li><li><p>Class Crinoidea </p><p> Feather stars and sea lilies </p><p> Suspension feeders that use outstretched feathery arms to obtain food from water </p><p> 600 species </p><p> some are restricted to deep water and attach to bottom (sea lilies) </p><p> come crawl on hard bottoms in shallow water to deep water in tropical Pacific and Indian Oceans (feather stars) </p></li><li><p>Class Crinoidea </p><p> resemble upside down brittle stars w/ ambulacral grooves and mouth upwards </p><p> larger organs are restricted to a small cup-shaped body from which arms radiate </p><p> may have from 5-200 arms w/ possible side branching </p><p> side branches have tiny tube feet that secrete mucus to aid in food catching </p></li></ul>


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