Lecture_11_24_2_Echinodermata

Lecture_11_24_2_Echinodermata - Remember the Deuterostomes...

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Unformatted text preview: Remember the Deuterostomes : Features: Phylogeny: three groups, two are major (Echinoderms, Chordates) one is relatively minor (Hemichordates) Echinoderms are just weird! No head Radial symmetry Echinoderms: A bizarre reversal Consider the metazoan tree. Three key Echinoderm features: Skeleton: calcified internal plates, epidermal covering Water vascular system: locomotion, feeding Pentaradial symmetry (adult), bilateral in larvae Adult sea star Larval sea star Water vascular system Central ring Side arm Ampulla Ampulla Suction cup 1-way valves Echinoderm diversity Crinoidea: Sea lilies & feather stars Asteroidea: Sea stars Ophiuroidea: Brittle stars, basket stars Echinoidea: Sea urchins Holothuroidea: Sea cucumbers Water vascular system C r i n o i d s S e a c u c u m b e r s S e a u r c h i n s B r i t t l e s t a r s S e a s t a r s Reduced skeleton Fused skeleton Loss of suckers Suckers Crinoidea: Sea lilies & feather stars-625 species, major diversity 300-500 million years ago-some can swim actively as adults (attached as juveniles)-both deep sea and on Pacific coral reefs...
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This document was uploaded on 01/24/2009.

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Lecture_11_24_2_Echinodermata - Remember the Deuterostomes...

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