3454lablecture8 - LECTURE 8 PHYLUM ECHINODERMATA 1st...

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LECTURE 8 PHYLUM ECHINODERMATA 1 st deuterostomes – blastopore forms anus first in development, then mouth forms from gut, coelom forms thru enterocoely Development: Unfertilized egg has nucleus Fertilized egg has no nucleus Cell splitting - cells stay same size Blastula stage – blastoderm surrounding hollow blastocoel Gastrula stage – ectoderm surrounding, blastopore invaginates into archenteron Larvae – systems begin to form Characteristics of Echinoderms: Share many features with Chordates: Tornaria larvae form similar to Hemichordata Enterocoelomate and deuterstome Echinoderms have no circulatory or excretory systems, only marine animals Primitively they have radial symmetry Water vascular system Tube feet Calcareous ossicles make up endoskeleton CLASSIFICATION CHANGES – NO MORE SUBPHYLA, NO MORE CLASS STELLUROIDEA, CHANGE ASTEROIDEA AND OPHIUROIDEA TO FULL CLASSES
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CLASS CRINOIDEA Sea lilies, Feather Stars Anus and mouth on oral side, 5-10 arms around central disk (Calyx)
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3454lablecture8 - LECTURE 8 PHYLUM ECHINODERMATA 1st...

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