Sea Star Time Lapse

Sea Stars Brittle Stars Sea Urchins Sea Cucumbers Sand Dollars

o Echinoderm means “spiny-skin” o Composed of an internal skeleton made of calcium carbonate plates called ossicles o Covered with spines and skin

o Occur at all depths in the ocean o Found only in salt water o Found in coral reefs, tide pools, rocky intertidal zones

o Born with bilateral symmetry o As adults they have radial symmetry

o Contain no blood, brains, or heart o Use a water vascular system: they use seawater instead of blood to pump nutrients throughout their body

Used for locomotion, respiration, and feeding Water-filled canals run throughout its body By varying the internal water pressure the echinoderm can expand and contract its tube feet Tube feet are muscular extensions of the water- filled canals Tube feet end in suckers for attachment and can detect chemical and mechanical stimuli

Sexes are separate Gametes released into the water and fertilization occurs externally Some sea stars, brittle stars, and sea cucumbers can reproduce asexually through regeneration, which is the ability to re-grow lost or damaged body parts

Asteroidea (sea stars) Ophiuroidea (brittle stars) Echinoidea (sea urchins) Holothuroidea (sea cucumbers) Crinoidea (sea lilies)

Average number of arms = five Blue World: Sea Stars

Some can have many more than 5!

Label the following diagram in your notes

Porous plate that allows for a change in pressure so that tube feet can get suction Acts like a water pressure valve

Feed on snails, bivalves, crustaceans, worms and corals Use suction of tube feet to open shells Extend its stomach out through its mouth to envelop food and enzymes break food down Sunflower Seastar Eating

 Snake-like movement  Named “brittle star” for their habit of breaking off arms as a defense  Tube feet used as tactile organs (sense of touch)  Arms used for locomotion and drawing food into their mouths  Typically hide under rocks or coral or bury beneath the sand

 The name “urchin” is an old name for hedgehogs  The spines inflict a painful wound when they penetrate human skin. Major predator is the sea otter!

 Mouth is made of five calcium carbonate teeth or jaws, with a fleshy tongue- like structure within.  Chewing organ is known as Aristotle's lantern  Urchins feed mostly on algae - killing kelp forests! Sea otter populations keep them in check

Sand Dollar: Related to the sea urchin

 Leathery skin and elongated body  Collagen that forms their body walls can be loosened and tightened at will  Can liquefy its body and pour into the space

When startled, the sea cucumber may expel their insides through a tear in the wall of their bodies through a process known as evisceration World's Weirdest: Sea Cucumber

True Facts About the Sea Pig

 Crinoids feed by filtering small particles of food from the sea water with their feather like arms.  The tube feet are covered with a sticky mucus that traps any food that floats past.  Once they have caught a particle of food, the tube feet can flick it into a stream of mucus towards the mouth.