What Are the Two Methods by Which Coral Can Reproduce?

Coral Facts

• Coral reefs are comprised of living animals that support more species per unit area than any other marine environment, according to the National Oceanic and Atmospheric Administration (NOAA). Even though they appear more rock-like or plant-like, coral are actually small cup-shaped organisms called polyps that may range in size from less than an inch up to several inches. Mushroom coral, one of the largest species, can grow up to 10 inches in diameter, while the tiny colonial polyps range from 0.04 to 0.12 inches across.

Sexual Reproduction

• Coral most commonly reproduce sexually, either by internal or external fertilization. During external sexual reproduction, or spawning, eggs and sperm are released into the water. Once fertilization occurs, swimming larvae develop. With internal fertilization, the eggs develop inside the coral polyp for several days to several weeks. Free-swimming larvae are then released into the water. Either way, the offspring drift over a broad geographic area before settling. They eventually settle on something firm like a rock, where the polyps create a reef.

Asexual Reproduction

• Asexual reproduction occurs in several ways. When storms or other environmental disruptions occur, polyps may break off from the colony before attaching somewhere else and starting new colony growth. This makes the colony more stable because the detached polyps reattach to the dead skeletons of old polyps. Asexual reproduction also occurs through budding. This happens when a polyp pinches off part of itself, enabling it to replicate itself several times while maintaining an organic link to the colony.

Hermaphroditic Coral

• Coral may be either male or female, but it is not uncommon for a coral to be hermaphroditic which means it has the reproductive cells of both sexes. During its life, a polyp may reproduce sexually and/or asexually. During external fertilization, synchronous spawning may occur when the polyps release both eggs and sperm into the water simultaneously. This spawning is affected by season and water temperature as well as tidal and lunar cycles. While spawning occurs at different times for different reefs, it always occurs a night or two after the full moon.