Coral is a living thing, an animal that reproduces as other animals do: either by sexual or by asexual reproduction. Some corals have sperm and eggs, while other corals reproduce by growing polyps that are genetically identical!
Some corals expand their territory and odds of survival through “bailout”, asexual fission or fragmentation, which allows corals to establish themselves in new areas after storms or where rough water moves things around.
The sexual reproduction methods include broadcasting sperm and eggs. Once the eggs are fertilized, they produce a type of larvae called planula. The planula head toward the light, where photosynthesis can go to work in a process called photaxis. After the photaxis leads to young adult coral, the new folk can head toward viable soil and begin to establish new colonies of coral!
There is synchronous spawning where one or many neighboring species broadcast sperm and egg, triggered by phases of the moon or by cycles of light. All of the species broadcast sperm and egg at the same time and in mass quantities, increasing the odds of fertilization and formation of planula.
One type of coral, ahermatypic coral, is called a “brooder”. These corals live in rough waters and do not attempt to establish reefs. They go with the flow, holding their sperm and eggs until they are in conditions that are best for breeding.
The asexual reproduction methods involve the growth of polyps that contain everything that is needed for an adult coral plant. The polyps can grow from the head, mouth, stomach or tentacles of the parent coral. With intertentacular budding, the polyp grows from the oral disc andgrows to the same size of the parent polyp. With the extratentacular budding process, the polyp grows from the base of the tentacle and is smaller than the parent polyp.
There is transversal asexual reproduction where the coral top splits into two parts: the top, or oral disc and the bottom, or basal disc. Each disc is then in charge of growing the rest of its body parts to become a whole, adult coral.
Finally, asexual fission involves coral simply breaking off to establish itself in a new location.
How does all of this look? Some corals are soft and rounded in shape, while others are hard and pointed in shape. The rougher the water, the flatter and more mounded the corals will be. In the calmest waters, the shapes can become fantastical, with delicate and complex branches and incredible shapes.
How long does all of this take? Several factors, including light, turbulence, salinity, food levels, and water temperature will affect the growing time. The slowest species can take a year to grow an inch or 25 millimeters. They can take a year to grow just 5 millimeters or 0.2 inches.
The faster growing species can grow up to 8 inches, or 20 centimeters in a year.
In summary, corals come in many species, with several ways of reproduction, appearance and growth rates. They are worth our time and effort to protect them and to give them a world in which to grow so that they sustain their lives and serve as habitats for an astounding variety of other lives.
Coral Reef Overview
Wikipedia, “Coral”
