How Do Corals Reproduce?

Have you ever wondered how corals make more corals?  They can’t move, so how do they reproduce?  To understand coral reproduction, you must first understand asexual reproduction and sexual reproduction.

Asexual reproduction involves only one parent and the offspring produced are genetically identical to the parent.  Two parents are needed for sexual reproduction.

Corals can reproduce asexually by budding or fragmentation.  With budding, coral polyps “bud” off from a parent polyp and expand or start new colonies.  With fragmentation, a piece of coral that has broken off of a larger colony can continue to grow elsewhere.

Most corals in the ocean reproduce sexually by broadcast spawning or brooding.  With broadcast spawning, corals release massive numbers of both male and female gametes (eggs and sperm) into the water column (usually at night).  This enables them to distribute their offspring over a larger area.  The gametes will fuse (fertilization) while in the water column and then settle on a hard surface and a new coral colony will start to form.  With brooding, only male gametes are released into the water column.  With luck, they will be taken in by female coral polyps that contain the female gametes and become fertilized.  After fertilization the gamete, now called a planula, is released into the water column to settle on a hard surface and start a new coral colony.

Brooding: release of male gametes. Photo: NOAA

Brooding: Release of planula. Photo: NOAA

Broadcast spawning. Photo:NOAA