How Does Coral Reproduce?

Gender

• Corals live in colonies on the ocean bed and can reproduce sexually and asexually. In addition, they come in all genders. They can be female, male and hermaphrodite. However, some corals within a colony have no gender at all and do not participate in the reproduction process. Many coral species also are able to change the gender within a polyp, according to the needs of the colony. When defining the sexuality of corals, scientists look at the colonies as a whole and categorize them as either female, male or, when both sexes appear, as hermaphrodite.

Budding

• Asexual reproduction in corals is called budding and can happen in two ways. Extra-tentacular budding occurs outside the individual polyps when a parent coral produces a daughter coral attached to the outside of its wall. The new coral is much smaller than the neighboring corals and will be squeezing in-between them. Intra-tentacular budding happens when a parent coral splits itself into two within its wall. In intra-tentactular budding, a section of wall grows in the middle of the existing polyp and divides it, thereby producing two new individuals. Coral colonies use asexual reproduction to increase the territory of the existing reef.

Internal Sexual Reproduction

• Corals also are able to start completely new colonies by sexual reproduction. Internal sexual reproduction involves brooding by a female coral. Male polyps will dislodge sperm that float through the water and find a female coral of the same species, enter her mouth and fertilize an egg inside. Depending on the species, the female broods the developing larvae for several days or weeks. It then releases the larvae, which float to a new location to settle and grow.

Spawning

• Some corals reproduce through spawning, where female polyps release eggs and male polyps spread sperm into the water. The sperm fertilizes the eggs, which develop into larvae called planulae that will float in the water for several days before settling at a location and starting to grow. Spawning usually happens once a year when the water has the right temperature. The process also depends on the lunar circle and happens within days of a full moon.