They try to camouflage themselves.
by blending in with its surroundings
Yes they do kick back their legs like a horse does to protect themeselves.
A sea urchin's body is covered in sharp spines.
They have to protect themselves from sea otters and birds
Tamed horses or domesticated horse allow for their owner to protect themselves. If you are referring to protecting themselves from predators then they will always do that regardless.
Having pointy spikes to protect themselves.
enimies
they use it to disguise themselves
dont dump toxic waist into the water
they protect themselves from larger carnivorous fish by hiding among the tentacles of Sea Anemones- which would sting and eat the larger fish... The Clown fish is immune to the Sea Anemone's stings.
Yes, sea stars are able to move the spines in order to protect themselves as armor.
they die and die