phylum echinoderm. echinoderm mostly sessil life adult has no head or brain central nervous system...
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EchinodermMostly sessil lifeAdult has no head or brainCentral nervous system with nerves radiating into armsAll marineEchinodermata spiny skinned
ContMost adults have pentaradial symmetry (all radial) Larvae have bilateral symmetry Separate sexes ; some hermaphrodites do exist Sea stars (not star fish); brittle stars; sea cucumbers; sea urchins, sand dollars, etc. ~ 8,000 to 10,000 species
CharacteristicsEndoskeleton an internal skeleton of calcium carbonate of tiny plates called ossicles- can be fused together2. Pentaradial (Five part radially symmetrical most have five arms)
Characteristics Cont3. Water vascular system water system of connective canals and tube feet that are used for: locomotion, gasexchange, sensory, and capturefoodTube feet muscular extension of water filled canals End is a sucker (attachment / locomotion)
Cont4. Coelomic circulation and respiration body cavity functions as a simple circulatory system where particles move through the fluid-Have skin gills projections that are between the spines
RegenerationMany species autotomize, leaving predators with a nutritious souvenir while they escapeMost sp. can regenerate from fragments
Sea StarsMost have 5 arms Some have more (even 50) Carnivores (Bivalves ; snails ; barnacles ; etc.)Ejects stomach inside out through mouth into the prey Digestive enzymes are secreted and the digested food is carried into the glands for absorption Stomach is then pulled back inside body
Feather Stars and Sea liliesMouth is located on the upper surfaceSessile but can detach & move around Attached to sea floor with a stalkMouth & anus on upper surface
Brittle StarsSlender branched arms that readily break off & regenerate Move quicker than sea starFeed by raking in food with arms or trapping it with its tube feet
Sea urchins and Sand dollarsHave the five distinct body partsBody shaped like a sphere (sea urchin) or a flattened disk (sand dollar) Lack arms Bodies covered with movable spines
Sea CucumbersSofterLack arms Live on ocean bottoms hiding in caves during the day Show bilateral symmetry Can eject parts of their internal organs (evisceration) to scare predators; regenerate these structures in days
HW1. List the major echinoderm characteristics2. Explain why some echinoderms would have bodies that are softer than others3. Compare and contrast two examples of echinoderms.