Habitat
The sea urchin lives on the rocky seafloor, from shallow waters to great depths.
Diet
Sea urchins eat plant and animal matter, including kelp, decaying matter, algae, dead fish, sponges, mussels, and barnacles.
Movement
The spines are used for protection, for moving, and for trapping drifting algae to eat. Among the spines are five paired rows of tiny tube feet with suckers that help with moving, capturing food, and holding onto the seafloor.
Description
The sea urchin is a spiny, hard-shelled animal. Sea urchins have a round body and long spines that stick out from the body. They have tiny stingers that are used for defense and for obtaining food. Sea urchins do not have a brain. The mouth is claw-like and is located on the underside; it has 5 tooth-like plates that point inwards and are called Aristotle's lantern.
Enemies
Sea urchins are eaten by crabs, sunflower stars, snails, sea otters, some birds, fish (including wolf eels), and people.