they hide behind sea plants and sneak up on the prey. they attack when they see a prey. usally they cacth them but not always
They use their tubed feet to help them catch their prey
How does a sea anemone trap their prey
The classification of a Sea Urchin is Echinoidea
sea urchin
The Purple Sea Urchin's diet consists of plants, animal matter, including algae, dead fish, sponges, decaying matter, mussels, barnacles, and kelp. The Purple Sea Urchin is the prey of crabs, sunflowers stars, snails, most birds, fish, sea otters, and humans. The Purple Sea Urchin is actually a delicacy in some countries.
A sea urchin does move, but not very frequently.
because the crab needs the sea urchin for protection and the sea urchin needs the crab for food
Ummm...it's the thing from which a sea urchin hatches?
I think a sea anenome and a sea urchin can live together because i have a little aquarium and there is a sea urchin and and a sea anenome (if that's how you spell it) living in there and they were perfectly fine. BUT if you have a sea urchin do not have any crabs in there, because my sea urchin killed one, and almost killed another one by taking its claw off. :(
a blue tuxedo sea urchin
Spines of the sea urchin can cause injuries of the skin.
It urges the sea to adapt to IT! The litle urchin urger.
A (street) urchin is a child who lives on the street, surviving by engaging in petty crimes. A (sea) urchin is a spiny creature (exoskeleton), with a soft interior. I welcome improvements to this answer.