Echinoderms_Chordate_Origins[1]

Echinoderms_Chordate_Origins[1] - Echinoderms,...

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Echinoderms, Hemichordates & Chordates The Dueterostome lineages
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Deuterostomes In both the traditional and newer phylogenies of animals, the Deuterostomes form a good monophyletic group, based on the fate of the blastopore, formation of the coelom, and other characteristics.
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The phyla of Deuterostomes don’t look all that similar as adults. Echinodermata Hemichordata Chordata
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They are related by • A common pattern of embryological development • Endoskeleton in most • Shared larval forms between the echinoderms and hemichordates
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Echinodermata (Starfish, Sea Lilies, Sea Cucumbers, etc) • Small Phylum-6000 species • All Marine • Plan of five • No head or brain • Tube feet for locomotion • Water vascular system • Dermal endoskeleton • Metamorphosis from bilateral larva to radial adult
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Another ancient group with fossils from the Cambrian
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Endoskeleton • Calcareous plates • From mesoderm
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Pentaradial Symmetry (Plan of Five)
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Echinoderm Larvae
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Water Vascular System • Derived from coelom • System of canals • Tubefeet • Respiration • Excretion • Food gathering • Locomotion
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Tube Feet • Locomotion • Respiration • Operate by a hydraulic system
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Major Groups of Echinoderms • Crinoidea- Sea Lilies • Asteroidea-Sea Stars • Ophiuroidea- Brittle Stars • Echinoidea- Sea Urchins • Holothruroidea- Sea Cucumbers
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Sea Stars • Common along shorelines • Arms not sharply demarcated from central disc • Tube feet with suckers • Many are predators
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Ophiuroidea- Brittle Stars Most active echinoderms Movement by arms rather than tube feet Sharply demarcated central disc Tube feet without suckers Scavengers, browsers or filter feeders
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Echinoidea- Sea Urchins& Sand Dollars • Adapted for the ocean bottom • Compact body in endoskeletal shell • Feed on algae and detritus
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Strangest of a strange group Greatly elongated
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This note was uploaded on 09/23/2011 for the course BIOL 240 taught by Professor Staff during the Spring '11 term at S.F. State.

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Echinoderms_Chordate_Origins[1] - Echinoderms,...

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