echinodermata spiny skinned. echinoderms *6000 living species 20,000 extinct species *all oceans,...
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Echinodermata
Spiny Skinned
Echinoderms* 6000 living species 20,000 extinct species
* all oceans, all depths
* Planktonic larvae - bilateral symmetry
* adult - pentamerous radial symmetry
* sexual external fertilization
* lack a head therefore have oral & aboral surfaces
* endoskeleton
* water vascular system *** only in echinoderms***
* tube feet and ampullae
* madreporite
vocabulary
• Water vascular system - network of water filled canals
• tube feet - muscular sacs that extend outside the body opposite ampullae. Used for attachment and locomotion
• madreporite - a porous plate on the aboral surface, connects water vascular system to the exterior
The 5 classes of Echinodermata
Phylum Echinodermata
Class Asteroidea
ClassOphiuroidea
Class Echinoidae
Class Holothuroidae
ClassCrinoidae
Asteroidea• Usually 5 arms, up to 50 arms
• Ambulacral groove - radiating channels on each arm, has hundreds of tube feet
• Pedicellariae - minute pincher like organs that help keep surface clean
• What do they eat? Snails, barnacles, bivalve, etc.
• How do they eat? Project their stomach into soft body of prey, partial external digestion
• EX. Sea Stars or Starfish Previous Slide
Ophiuroidea
• 2,000 species
• What do they eat? Organic material
• Arms are long thin and very flexible.
• Arms lack suckers on tube feet. They are not used for locomotion but for feeding and sensory.
• EX. Basket stars, Brittle stars and sea serpents
Previous Slide
Echinoidea• Rigid test with movable
spines and pedicellariae
• Arms moved up to meet at the top
• Now ambulacral grooves extend from top to bottom
• What do they eat? Plant material, encrusting animals, dead organic matter
• Aristotle’s lantern - jaws and muscles
• EX sea urchins and sand dollars
Previous Slide
Holothuroidea• Elongated body
symmetry
• Endoskeleton: microscopic calcareous spicules throughout watery skin
• 5 rows of tube feet from mouth to anus
• Evisceration - sudden expulsion of gut and other internal organs
• EX. Sea cucumbers Previous Slide
Crinoidea
• 600 species• 5 to 200 arms • Mouth is located on
the ventral surface• mucus • filter feeders• EX. Sea lilies, Feather
stars
Previous Slide