St Thomas, US Virgin Islands. Magens Bay.jpg

Types of Coral and Life Cycles

Preserving Our Precious Caribbean Coral Reefs

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Coral in the Caribbean

At Alpha Submarine Adventures, our aim is to promote awareness and conservation of coral reefs, one of the world’s greatest natural resources. On this page you’ll find information on some common types of coral in the Caribbean, their life cycles, and how they underpin the entire reef ecosystem. In the Caribbean alone, these and other coral species support the livelihoods of millions of people and capture the imaginations of thousands of tourists each year.

Unfortunately, corals in the Caribbean and elsewhere face numerous threats in our changing world. Many of the reefs we visit and study today took thousands of years to form, but rising ocean temperatures and other drastic environmental changes means they might well be gone in the next lifetime. In just the last 30 years, the world has lost 50% of its coral reefs. If corals are to survive, many more people will need to fully grasp their importance and fragility.

Alpha Submarine Adventures is working to do just that—and more—and you can help! Donate today to help fund ecotourism adventures that will not only help raise awareness of the importance of reefs but also collect vital data that marine researchers will use for scientific and conservation efforts. Vital information about reef life and how it is responding and adapting to a rapidly changing environment is essential if these biological wonders are to be preserved. Help out the Alpha mission with your donation today!

Basic Facts About Coral

Coral Reef Island

Corals look like bright rock formations on a reef, but they are actually colonies of millions of small, genetically identical organisms called polyps. In some types of coral, polyps break or “bud” off of the parent colony, fasten onto a rock, and start a new colony. Or, smaller colonies break off of a larger colony to form new ones in a process called “fragmentation.”

 

Still other types of corals, such as brain or star corals, reproduce sexually, producing both eggs and sperm. Fertilized coral eggs then become larvae, which drift up to the surface before sinking to the bottom again. Once coral larvae attach themselves to rock, the larvae transform into polyps and begin colonies.

 

Shallow-water corals have a symbiotic relationship with a certain type of algae called zooxanthellae: the coral provides protection and compounds necessary for algae photosynthesis, while the algae in turn produces carbohydrates that the coral uses as food and oxygen. Too much algae, however, can offset this relationship and damage coral.

Providing shelter and protection for fish and crustaceans is just one of the many ways coral polyps help anchor the reef ecosystem. Here is some more information about some common Caribbean corals.
 

Pink Earth

Grooved Brain Coral (Diploria Labyrinthiformis)

Thanks to its unique shape and large size, the brain coral is commonly represented in illustrations, movies, and TV shows. It is named for its labyrinthian texture, which resembles the folds of the human brain. Brain corals grow fairly large, up to 6 feet in diameter, and are foundational reef-builders. They reproduce sexually by releasing sperm, which is collected by other individual polyps and used to fertilize eggs. The eggs hatch into larvae, which return to the seafloor to become polyps and start new colonies. Unlike other species such as the elkhorn, brain corals are relatively abundant, though they are vulnerable to bleaching and other issues affecting modern reefs.

Marine Biologist
Diving in the Reef

Elkhorn Coral (Acropora palmata)

Colonies of these corals resemble a fully developed set of elk antlers and are typically a light tan to brownish color. It is one of the fastest-growing corals, and individual colonies can grow to heights of about 6 feet, providing great protective cover for fish. Elkhorn corals reproduce sexually, with each colony producing both egg and sperm.

Beginning in the 1980s, elkhorn populations were reduced by more than 90% by white band disease, which attacks coral tissue. While scientists are not certain of the disease’s origin, they have theorized that it thrives on algae-covered coral. Other research has shown that some fish species, like parrotfish, are effective algae-eaters and may be key to reef survival in the future.

Pink Earth

Staghorn Coral (Acropora cervicornis)

A relative of the elkhorn, staghorn coral takes the shape of a more underdeveloped set of antlers. It comes in the same variety of colors as the elkhorn, and is vulnerable to the same white band disease. Staghorn reproduces sexually by emitting both eggs and sperm, but can also asexually reproduce through fragmentation.

Coral Reef
Scuba Diver and Corals

Great Star Coral (Montastrea cavernosa)

These large, oblong-shaped coral are covered with hundreds of small, round coralites that resemble an octopus’s suckers. Their color ranges from vivid pinks and oranges to grays, browns, greens, and yellows. Unlike the staghorn, which produces both eggs and sperm, great star colonies are either male or female. The colonies release the eggs and sperm at once during a great spawn that usually occurs on a late summer night about a week after a full moon.

Learn More About Our Mission And Donate To the Cause

Ready to learn more about how you can invest in our submarine adventures, and how we’re working to protect our coral reefs in the Virgin Islands? Eager to get started right away? Make a donation here!