Echinodermata

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Echinodermata
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Deuterostome characters
Can you list them?
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Phylum Chordata
Vertebrae
All four chordate characteristics retained
throughout lifetime
Notochord
Tadpole like larvae with post-anal tail
Dorsal Hollow Nerve Chord
Gill Slits
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Classification of Deuterstomes
Phylum Echinodermata
Phylum Hemichordata
Phylum Chordata
Subphylum Urochordata
Subphylum Cephalochordata
Subphylum Vertebrata
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Pelagic marine worms
Named for stout spines around mouth
Highly predaceous on copepods and fish
Mouth spines snap shut on prey
About 65 species (to 10 cm)
Phylum Chaetognata
arrow worms
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Phylum Echinodermata
The spine skins
Characteristics
Calcareous dermal endoskeleton
Pentamerous radial symmetry after metamorphosis
Water vascular system
No head or brain WHY?
Date back to Cambrian
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Starfish as sample echinoderm
-ambulacral grooves
-showing 5-sided symmetry
open in some forms, closed in others
-central mouth
-tube feet of water vascular system
Oral surface
Aboral surface
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Digestive system
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Function(s)?
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Phylum Echinodermata
Class Asteroidea
Sea stars
Brittle stars
Class Ophiuroidea
Sea urchins
Class Echinoidea
Class Holothuroidea
Sea cucumbers
Class Crinoidea
Sea lillies
Plus two fossil classes
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Class Crinoidea
Sea Lillies
Sessile and stalked - thus plant-like
625 living species, many more fossil, perhaps 5000
Ambulacral grooves open
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-ambulacral grooves open
-tube feet powerful enough to open bivalve
molluscs
-stomach everted through mouth into prey
-dioecious with external fertilization
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Class Ophiuroidea
Brittle stars
Arms are snake-like (Ophio)
-break off easily
-ambulacral grooves closed
-on oral surface
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Class Echinoidea
Sea urchins, sea buscuits, sand dollars
Endoskeletal plates joined into one continuous
shell
Ambulacral grooves closed
Move using tube feet
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All echinoids have an Artistotles latern
A five part chewing system
Important marine herbivores
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Class Holothuroidea
Sea cucumbers
Elongate and secondarily bilateral
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Endoskeleton is reduced
Leathery and can spew out viscera and grow new
ones
Slide along on tube feet
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