1. Echinodermata
Spiny Skinned

2. 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

3. 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

4. The 5 classes of Echinodermata

5. Asteroidea Previous Slide 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

6. 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

7. Echinoidea Previous Slide
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

8. 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

9. Crinoidea 600 species 5 to 200 arms
Mouth is located on the ventral surface
mucus
filter feeders
EX. Sea lilies, Feather stars
Previous Slide