echinoderms quiz (phylum: echinodermata)

enchinoderms

• “spiny skin”

• pentaradial symmetry

• water vascular system (“tube feet”)

• hard exoskeleton made of bony spines

• sexual reproduction

• no brain, but they have a nervous system/ring

sea stars

• mostly carnivores

• eat bivalves (clams, mussels, etc)

  • uses tube feet to pull shells apart + inject stomach to digest prey

• madreporite: controls its water vascular system, located @ the bottom of the star

• arms can be regenerated if part of the central disk is attached

feather stars

• oldest group of echinoderms

• can swim

• long feathery arms

• filter feeders

brittle stars

• have tube feet, but mostly move by crawling w/ arms

• can detach arms + regenerate

• filter feeders or detritivores

sea urchins

• no distinct arms

• spines for protection

  • can be venomous

• eat mostly algae or detritus

• Aristotle’s Lantern

• very similar to sand dollars

• nerve ring replaces brain

sand dollars

• no distinct arms

• spines or protection

  • can be venomous

• eat mostly algae or detritus

• very similar to urchins

• filter feeders

sea cucumbers

• Detritivores

  • eats dead organic material from sand

• can eviscerate

• filter feeders

evisceration

• can be done by sea cucumbers

• spewing non-essential organs out to scare/deter predators

water vascular system

• used for gas exchange, feeding, and locomotion

aristotle’s lantern

• “teeth” attached to the mouth of the sea urchin used to chew the holdfast of kelp

• 5 teeth

tube feet

• proper name: podia

• used for locomotion + food collection

• water pressure in hydraulic canals (water vascular system) force the tube feet to expand/retract, allowing movement

echinoderms that are also filter feeders

feather stars, sea cucumbers, brittle stars, sand dollars

which echinoderm can turn its stomach inside out?

sea star (done to eat clams)

difference in how the brittle star and the urchin moves

the urchin uses its tube feet to move while the brittle stars moves with its arms and legs, tube feet are used to move food

why is it difficult for a sea urchin’s spine to be removed?

it has a barb embedded into the skin, when the spine and skin are embedded together it is called a test