for protection
No, a sea urchin and a sea anemone are two different sea creatures nothingalike.They do have some alike characteristics.like they both use their long tentacles , or spikes for protection.
Sea Urchin !
Sea urchin spikes are called "spines." These spines are made of calcium carbonate and serve various purposes, including protection from predators and aiding in locomotion. They can vary in size, shape, and color depending on the species of sea urchin. Additionally, some species have venomous spines that can deliver a painful sting.
the sea urchin has many adaptions like its spikes to protect it self from predators.
they use the poison in there spines to defend themselvesfor example when a predittor gets to close or steps on the sea urchin it releases a poision.
they puff up like a ball with spikes. It looks something like sea urchin when it puffs up.
The classification of a Sea Urchin is Echinoidea
sea urchin
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
Depending on the species, sea urchins range in size from a few inches across (small rock-boring urchins) to a foot or more across (pencil urchins and venomous hollow-spined urchins). THATS NOT HELPFUL!!
Ummm...it's the thing from which a sea urchin hatches?