Purple Sea Urchin Facts

Sea urchins come in many colors, with the most common being purple and light pink. Purple sea urchins are classified as species Strongylocentrotus purpuratus, and they live from the Alaskan to Mexican Pacific coastline. These are very primitive animals, having been in existence about 450 million years.

  1. Body

    • Purple sea urchins have a round body with a flat bottom, and they measure about three to four inches in diameter. Their skin is covered with a shell made of hard chalky plates, and spiky spines radiate from the body. These spines protect the sea urchins from predators and also help them move.

    Mouth

    • The sea urchin has a mouth underneath its body, along with five teeth or toothlike plates. It uses the teeth to tear food from rocks and also to dig holes for hideaways.

    Food

    • Sea urchins graze on algae and barnacles on hard surfaces. They also eat kelp, seaweed, plankton, dead fish, small sea animals, mussels and sponges.

    Location

    • Sea urchins usually live in shallow areas of water, such as a tide pool, along a coast with strong wave action.

    Caution

    • Sea urchins are not aggressive, but they may injure a swimmer or diver who steps on them or picks them up. Their spines create puncture wounds, and they also have defensive structures called pedicellariae between these spines that release venom. Sometimes the injuries require medical treatment.