echinoderms

chapter 2 exam - BIO 305

echinodermata

• sea stars

• brittle stars

• urchins + sand dollars

• sea lilies + feather stars

general characteristics

• fluid filled canals

• flexible appendages

• about 7,000 spp.

• strictly marine, mostly benthic

• pentamerous symmetry (adults)

water vascular system (SUPER IMPORTANT)

• a hydraulic network for movement, feeding and waste / gas exchange, using water pressure to move tube feet for movement and manipulation of environment

tube feet

• “smell” environment

• locomotion

• prey capture

• adhere to substrates (suction and secretions)

ossicles (bones)

• urchins + sand dollars

• sea cucumbers

• sea star

movement

• using spine to move

• sea cucumbers crawl on tube feet (5 rows)

• sea lilies / feather stars crawl on arms + swim

sea lilies + feather stars (crinoids) SEE NOTES FOR DRAWING

• ~600 spp

• diverse fossil record

• filter feed:

  • cilia

  • mucus

sea star

• ~1,800 spp

• most are predators + scavengers

• irreverisble cardiac stomach extruded onto or into their prey

• east coast:

  • common sea star

  • forbes’ sea star

• west coast

  • bat star

  • purple sea star: keystone spp

  • giant sea star

more sea star examples

• sunflower sea star (fast →1 m/min)

• crown of thrones sea stars

  • eat coral polyps

  • venomous

brittle stars

• ~2,000 spp

• movable arms

• predators + scavengers

• filter + deposit feeders

• ex:

  • daisy brittle

  • notched

  • green serpent

sea cucumbers

• ~1,800 spp

• worm shaped body

• suspension + deposit feeders

• small ossicles embedded individually in the body wall

• breathe through anus

• ex.

  • north atlantic species

sea urchins + sand dollars

• ~950 spp

• ossicles are joined to form a rigid skeleton

• movable spines

• herbivores + suspension feeders

sea urchin examples

• purple sea urchin

  • pacific coast

  • biomedical research (alzheimer’s + cancer)

  • developmental research / embryology

• purple spined sea urchin

  • maine to cuba

asexual reproduction:

• regeneration

• most capable of regeneration of lost parts

scientific names for echinoderms

echinoidea → echinoids

holothuroida → sea cucumber

ophiuroidea → brittle stars

asteroidea → sea star

crinoidea → sea lilies