Marine Biology: Echinoderms
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what does echinodersm mean?
- -usually have 5 point radial symmetry
- -have an internal skeleton
- -tube feet
- -over 5000 species
- -breathe through skin or tube feet
- -MARINE only
what are the major types of echinoderms? and which organisms are found there
- Asteroidea: Sea Star
- Echinodea: san dollars and sea urchins
- ophiuroidea: brittle stars and basket stars
- holothuridea: sea cucumbers
- crinoidea: sea lilies and feather stars
- -5 point symmetry
- -has 5 appendages
what do asteroideas eat?
- bivalves (clams and muscles)
- othe sea stars
how do sea stars digest?
which sea star is a cannibal?
how does the tube feet work?
moves through use of water vascular system - water fills tube feet and hydrostatic pressure occurs
how do asteroidea reproduce
- -separate sexes (cannot be determined externally
- -fertilization is external
- -development is external and larvaes live as meroplanktons until grown up
- -round body
- -no arms
- -bodies are enclosed by a hard endoskeleton
- -can be found in shallow waters to deep seas
what do echinodeas prefer?
- solid/ rocky substrates
- -hebivores (they eat algea, seaweed, and kelp.)
- -can often be dangerous to kelp forests
how do echinodeas (sea urchins) move?
- use spines and tube feet to move. NO arms.
- have an endoskeleton made of calcium carbonate
- -have toxins in spines and can be painful
so there's the sea urchin, what else in apart of the chinodeas?
characterize sand dollars
- have short spines to help them burrow in the sand.
- filter feeders and use spines to catch planktons and organic matter
describe a sea biscuit
thicker than the sand dollar and also a filter feeder.
-largest class of echinoderms
characterize brittle stars:
- -nocturnal: active at night. Usually hides under rocks and tight places during the day
- -dos not use tube feet
- -fastest of all echinoderms
- -can regenerate arms also
- -have large flattened central disks
how do ophiuroidea eat
suspension feeders that gather particles
where are basket stars found? how do they eat
deep sea only. suspension feedes and use their branches to catch and trap food
characterize the holothuridea class
- -no skeleton
- -no arms
- -filter feeders
- -uses hydrostatic pressure to elongate body and adjsut its texture
what happens whatn holothurideas are disturbed?
release sticky tubules from their anus and it adheres to potential predators.
when agitated or threatened, sea cucumbers will release their digestive organs to avoid being eaten.
- -includes sea lilies and feather strs
- -ancient species which look like flowers and are the most primitive
how do crinoideas feed?
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