Any animal need oxygen for respiration.
Here are some sentences.Sea urchins have spines.Have you ever seen a sea urchin?
No. Sea urchins live in the sea.
Yes, they use a gas exchange (oxygen in and carbon dioxide out) taking place by diffusion across cell membranes of the tube feet.
More sea urchins.
The classification of a Sea Urchin is Echinoidea
there are excatly 3million purple sea urchins
sea urchins eat kelp.
Mostly for protection and also for locomotion.
Echinoderms.
No. Sea urchins are primary consumers and only eat sea weed, algae and kelp.
in the sea
Sea urchins are not as popular a subject for laboratory experimentation as rats or fruit flies, however, they have been studied. Scientists like to study practically everything.