• 1) Particle feeding is believed to be the primitive mode in echinoderms
  
  a) crinoids capture suspended particles with simple, mucus-covered podia bordering the pinnules of long feather-like arms; ciliated grooves move food to the mouth
  b) ophiuroids capture suspended or deposited particles with simple, mucus-covered podia or spines bordering the arms or mucus nets; a bolus of particles is moved toward the mouth by podia
  c) holothuroids capture suspended or deposited particles with large, branched, mucus-covered tentacles (modified buccal podia); the entire tentacle is drawn through the mouth to ingest food
  d) irregular echinoids (sand-dollars, heart urchins) live in sediment; many small podia underneath spines move particles to branching grooves in the test and then along grooves to the mouth

• 2) Some groups feed on larger items
  
  a) asteroids are mostly scavengers or carnivores; primitively, they swallow prey whole, but most can evert their stomach to feed
  b) regular echinoids ('true' urchins) feed on algae & encrusting invertebrates with a remarkable scraping device: Aristotle's lantern

• 3) Primitive crinoids were sessile, with jointed cirri on a long stalk

• 4) The remaining echinoderms move in a great variety of ways
  
  a) slender, jointed appendages (cirri in mobile crinoids)
  b) coordinated tube feet (asteroids, regular echinoids, holothuroids)
  c) rapid whip-like movement of arms (ophiuroids)
  d) undulation of entire body (some holothuroids)

• 5) Sexes are separate and fertilization is typically external
  
  a) the early larva is bilaterally symmetrical and primitively exhibits a tri-partite coelom (axocoel, hydrocoel, somatocoel)
  b) the water-vascular system arises from the fused axo-hydrocoel
  c) the perivisceral coelom arises from the somatocoel
  d) many groups possess morphologically complex feeding larvae; some larvae pass through a dramatic metamorphosis

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