Sea Urchin Offspring Facts

More than 200 different species of sea urchins have been discovered. Sea urchins are found in waters all over the world. Although urchins are plentiful, populations have declined as the result of pollution. According to Enchanted Learning and A to Z Animals, it takes 2 to 5 years for a fertilized sea urchin egg to grow to full maturity.

  1. Fertilization

    • Sea urchins typically reproduce in the spring. Male urchins release sperm into the water while females release eggs.

    Waiting

    • Fertilized sea urchin eggs rise to the water's surface where they float with plankton until they hatch. It may take several months for the eggs to hatch.

    Larva

    • Hatched sea urchin larvas are so small they are hard to see with the naked eye. Larva continues to float in plankton or drift in the water while they develop into juvenile urchins.

    Juveniles

    • Juvenile sea urchins look like small versions of their adult counterparts. Juvenile urchins go to the sea floor where they hide in rocks, shells and reefs until they reach maturity.

    Adults

    • Upon adulthood, sea urchins leave their hiding paces on the bottom of the ocean floor and move in search of food. Up until now, the young urchin has been feeding on algae and tiny animals that have floated nearby.