Marine Biology: Echinoderms

spiny skinned

• -usually have 5 point radial symmetry
• -have an internal skeleton
• -tube feet
• -over 5000 species
• -breathe through skin or tube feet
• -MARINE only

• 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
• -benthic
• -has 5 appendages

• bivalves (clams and muscles)
• othe sea stars

externally

sun star

moves through use of water vascular system - water fills tube feet and hydrostatic pressure occurs

• -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

• solid/ rocky substrates
• -hebivores (they eat algea, seaweed, and kelp.)
• -can often be dangerous to kelp forests

• use spines and tube feet to move. NO arms.
• have an endoskeleton made of calcium carbonate
• -have toxins in spines and can be painful

sand dollars

• have short spines to help them burrow in the sand.
• filter feeders and use spines to catch planktons and organic matter

thicker than the sand dollar and also a filter feeder.

-largest class of echinoderms

• -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

suspension feeders that gather particles

deep sea only. suspension feedes and use their branches to catch and trap food

sea cucumbers.

• -no skeleton
• -no arms
• -filter feeders
• -uses hydrostatic pressure to elongate body and adjsut its texture

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

suspension feeders