chapter 7 phylum echinodermata. characteristics: characteristics: –name means “spiny skin"...
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Chapter 7Phylum Echinodermata
Phylum EchinodermataCharacteristics:Name means spiny skin" EndoskeletonWater vascular system with tube feet important in feeding and locomotionSkin gills for respiration.Radial symmetry in adults- larvae are bilaterally symmetricalNervous system is decentralized- No brain - this allows any portion of the body to leadCan regenerate lost body partsAll 7000 species exclusively marine
Sea starsMove with tube feetHave a central disc in center of body surrounded by five arms (or multiples of 5 arms)Internal organs extend through the entire body, including the armsCalcium carbonate plates are loosely embedded in spiny skin making them slightly flexible Carnivores that normally consume shellfish and coral
Diagram of Sea Star
Class OphiuroideaBrittle starsLike sea stars, they have a central disc surrounded by armsFive arms seen in brittle stars are thin and covered in numerous spinesInternal organs are restricted to the central discThe tube feet present in brittle stars are without suckers and used for feeding on detritus and small animals
Class EchinoideaSea Urchins, Sea Biscuits, Sand DollarsElongated, movable spines much longer than those sea in other groupsRigid plates are fused into a solid structure called a testMove with tube feetMouth on the bottom, anus on top of bodyBiting mouth for grazing Aristotles lantern is the feeding structure of muscles and mouthpiecesFeed on detritus, encrusting organisms, algae or anything else they can scrape off surfaces
Class PelmatozoaCrinoidsfeather stars and sea lilies600 species are typically found in deep waterSea lilies live attached while feather stars are mobile5 or more arms that branch out for suspension feeding Some use a mucous net to aid in food capture
Class HolothuroideaSea cucumbersFive rows of two feet are restricted to one side, where the animal liesPlates found in the sea cucumbers are loosely embedded in the thick skinDeposit feeders or suspension feedersSea cucumbers have a interesting predator escape plan called evisceration, where they expel the internal organs; it is assumed this allows escape for the sea cucumber.Since all echinoderms have regenerative capabilities, these internal organs will grow back.
Video about EchinodermsThe Shape of Life