When we dive at Glover’s Reef, the primary species of coral we see are:
Staghorn Coral: They possess, like all corals, stinging nematocysts, but these can pack a bit of a sting if you touch them. Observed closely, their individual corallites can be seen; each bump on the branch is an individual coral animal.
Pillar Coral: This coral is occasional-to-rare in our area. It is also one of the few that actively feeds during daylight hours. You can actually see it tentacles groping for food, which gives it a fuzzy appearance. Individual small colonies can be found in numerous patch reefs near Long Caye by the observant diver. One large colony was once spotted off Northeast Caye between the reef and the wall drop off, in about 30 feet of water.
Golfball Coral: These can be spotted throughout the reefs near Long Caye; they are small, half spheres attached here and there on top of other dead corals. This is a Star Coral, and each corallite is easily distinguished from another.
Brain Coral: There are many kinds of Brain Coral, and it is rewarding to begin to distinguish between different species. The most common one seen is Symmetrical Brain Coral. Another type often seen but just as often not recognized as a separate species is Grooved Brain Coral. A third, common species, that is very similar but still distinctive enough for the layman to distinguish is Boulder Brain Coral.
Lettuce Coral: The prominent coral seen off the barrier reef of the atoll, north of Northeast Caye. A beautiful coral.
Fire Coral: You should not touch any coral (it’s not good for them), but this one, you definitelydo not want to touch it, because it’s not good for you. Fire coral earned its name for a reason. The sting has been compared to feeling as if an ice pick has just been jabbed into your hand.
Flower Coral: This beautiful species has large, widely spaced polyps on long stalks, that appear to originate from a central core. Only found occasionally, sometimes only in groups of 4-5 polyps.
Elkhorn Coral: Prefer shallow areas where wave action causes constant water movement. Branches orient parallel to surge direction. A rapidly growing coral, under optimum conditions can grow 5-6 inches a year.
This article in the New York Times highlights recent discovers about a particularly unique jellyfish, Turritopsis dohrnii, more commonly known as the immortal jellyfish. Even though we don’t see this species down in Belize, we do see two varieties at Glover’s Reef, the Upside Down Jellyfish and the Sea Thimble Jellyfish. They are discussed in this post following the brief excerpt from the NYTimes article.
Sommer was baffled by this development but didn’t immediately grasp its significance. (It was nearly a decade before the word “immortal” was first used to describe the species.) But several biologists in Genoa, fascinated by Sommer’s finding, continued to study the species, and in 1996 they published a paper called “Reversing the Life Cycle.” The scientists described how the species — at any stage of its development — could transform itself back to a polyp, the organism’s earliest stage of life, “thus escaping death and achieving potential immortality.” This finding appeared to debunk the most fundamental law of the natural world — you are born, and then you die. (read the full article here…)
The two jellyfish we see most often on Adventure Island are the Sea Thimble and the Upside Down. Jellyfish are not always present in the waters of Glover’s Reef but they do drift through regularly and unpredictably. Therefore, we advise all our guests to wear dive skins (light weight skin protection and thin thermal insulation) whenever they enter the water. These dive skins help prolong your diving time and also protect the skin against rashes caused by proximity to a cloud of jellyfish.
Sea Thimble Jellyfish — This marine animal is a small jellyfish resembling a thimble that measures about 1″ in diameter and is conspicuosly mottled with dark brown markings. This Jellyfish, together with corals, seaanemones, hydeoids and hydras are included in a group of animals without skeletons named cnidarians. One characteristic of this important group is that they have numerous stinging cells called nematocystswhich act as microscopic syringes to inject toxins when touched.
Along the Mexican Caribbean coast dense aggregations of the Thimble Jellyfish appear everyyear from late January to early June. The jellyfish occur in three swimmming stages as juveniles or ephrae, as adults and as larvae or planulae. They are transported by winds and currents to other areas on the time scale of a few hours to a few days.
Upside-down jellyfish is a genus of true jellyfish and the only members of the family Cassiopeidae. They are found in warmer coastal regions around the world, including shallow mangrove swamps, mudflats, and turtle grass flats in Florida. The medusa usually lives upside-down on the bottom, which has earned them the common name. Where found, there may be numerous individuals with varying shades of white, blue, green and brown.
They have a mild sting since they are primarily photosynthetic, but sensitive individuals may have a stronger reaction. The photosynthesis occurs because, like most corals, they host zooxanthellae in their tissues. The stinging cells are excreted in a mucus; swimming over these jellies (especially using swim fins) may cause transparent, essentially invisible, sheets of this mucus to be lifted up into the water column, where they are then encountered by unsuspecting swimmers. The stings, appearing in the form of a red rash-like skin irritation, are notorious for being extraordinarily itchy. Sometimes this jellyfish is picked up by the crab Dorippe frascone(family Dorippidae) and carried on its back. The crab uses the jellyfish to defend itself against possible predators.
While many people go to the Caribbean for nothing more than sitting in the sun with a cocktail in hand, there’s more that the Caribbean has to offer. For one, not just a couple seasons of warmth, but pleasant weather year-round. With such clear waters to go with that, the Caribbean is one of the top diving destinations in the world. Here, courtesy of Cheap Air’s blog, is a list of a few of the best destinations to scuba dive in the Caribbean:
Aruba: If you’re less into marine life and more into wrecking diving, then put Aruba at the top of the list. Many cite Aruba as one of the top wreck diving destinations in the world, with opportunities for both experienced and novice divers. One of the most notable wrecks is the Antilla, a 400-foot German freighter. Since the location of the ship has such little current, it’s accessible by divers of varying skill levels.
Belize: For a full diving experience, head to the waters just off the shores of Belize. Belize isn’t in fact an island, but that doesn’t mean it doesn’t offer some of the best diving waters in the world. The Belize Barrier Reef helps make up the second largest barrier reef in the world, the Mesoamerican Barrier Reef System. However, no diving trip to Belize is complete without a visit to Glover’s Reef.
Turks and Caicos: The Turks and Caicos are often overlooked as a diving destination, making the diving spots often a lot less explored than many other destinations. It offers a good mix of marine life and wrecks. Not far off from Turks and Caicos are drop-off spots, where the elevation can drop off thousands of feet below sea level. This is recommended for the more experienced divers.
Cayman Islands: The Cayman Islands make their way onto this list because it offers great opportunities for divers of all levels. There are tons of diving operators, many of which make it easy and cheap to get your diving certification. I recommend the Cayman Islands for the person just getting started who is more interested in the experience and a first-hand look at Caribbean marine life.
Grenada: Grenada is another destination that often gets overlooked by travelers. However, for the diving enthusiast, this is another destination that should be at the top of your lists for its wreck diving. Some of the more notable wreck sites in Grenada include the Titanic of the Caribbean, a 600-foot cruise ship, and the Isle of Wrecks. Many of these wrecks are recommended for more experienced divers since currents can be strong.
A coral reef in the sea is like an oasis in the desert. Tropical seas are poor in nutrients and devoid of shelter, but the reef teems with life. Food for sea life is found there in the form of algae and small fish and crustaceans for larger fish to eat. Protection for sea life is also provided in the form of elaborate architecture that provides shelter from both wave action and from predators. The result of this oasis is the world’s oldest ecosystem and what may be the most complex animal and plant community on earth, rivaled only by the tropical rainforest. The coral ecosystem encourages the evolution of organisms that have become highly specialized. Coral reefs probably support a larger number of animal and plant species than any other ecosystem in the world.
What accounts for the abundance of food and shelter in the midst of an ocean deficient in food? How can food and shelter be manufactured out of what appears to be nothing? The answer is primarily the coral polyp. The coral polyp is a small, simple animal that produces a stony skeleton and forms colonies with adjoining polyps. Together the linked skeletons can result in a colony weighing many tons and occupying dozens of cubic feet of space. Neighboring colonies form reefs that may extend for hundreds of miles. Coral is a living invertebrate and flourishes in warm, tropical waters. By drawing calcium carbonate from seawater, they build skeletal structures in an infinite variety of shapes and sizes. Because hard corals form the foundation for all of the tropical reefs of the world, they are considered to be the most significant invertebrates in warm, shallow seas.
But the polyp cannot by itself create and supply with food the inhabitants of the tropical reef. Left alone a coral polyp grows too slowly to build, and after a hurricane to rebuild, a large reef. Since a polyp is an animal it consumes food but does not create it except for the few fish that eat coral.
The key to the ability of polyps to be productive, shallow water reef builders and food suppliers lies within the fact that the coral polyps live in a close symbiotic (mutually beneficial) relationship with a plant, an algae called zooxanthellae (zoh-zan-THELL-ee), that lives within the tissues of the polyps. Using photosynthesis, the zooxanthellae take the polyp’s wastes and convert them into nutrients and oxygen for the polyps. Also, since polyps are animals they do not require light and do not need to live near the surface of the ocean. Reefs built by polyps alone would be smaller than those we see at Glover’s Reef, and they might well exist at great depths where we would never see them (some corals have been found at depths of 18,000 feet.) Because the zooxanthellae are plants, they require sunlight for photosynthesis. As a result, reef-building corals flourish only in shallow tropical waters. Zooxanthellae also promote calcification. A coral skeleton will grow 14 times faster in sunlight than in darkness. The reef wall of Glover’s Reef is at least a million years old.
The presence of the zooxanthellae within the tissue of the coral polyp was not discovered until after WWII. The discovery solved a great mystery. All food chains are build on a foundation of plants which produce energy and food for animals. However, plant life was thought to be lacking in tropical reef communities. Without the availability of plentiful food for organisms on the lower end of the food chain, scientists were unable to explain how coral reef ecosystems supported themselves. The discovery of enormous quantities of microscopic zooxanthellae enabled scientists to understand how coral reef ecosystems are able to flourish. Zooxanthellae are so numerous that in some instances the biomass of zooxanthellae comprise as much as 80 percent of the total weight of the coral polyps.
Coral reefs are composed of numerous individual coral polyps, which form immense colonies. As larvae, polyps initially swim freely; this is how they spread out to form new colonies. In order to begin formation of a coral head, the coral has to attach to an existing rock beneath the surface of the water. The polyp is pushed up as it builds and its’ calcium carbonate secretions harden. It then remains on the surface of the skeleton it has created. When an old polyp dies, the living polyps remain attach to its skeleton, continually growing. The living part of the polyp is composed of small tentacles that move continually, collecting minute plankton to provide the coral animal with food. Most corals feed at night but a few, like pillar coral, feed during the day. If they are feeding and you look closely, you can see each individual tentacle waving gently in the current. A coral reef is build by billions upon billions of individual coral polyps.
Although each polyp is an individual animal that can survive by itself, the usual mode of life is communal. Colonies of polyps are interconnected by a horizontal sheet of tissue that connects their body walls. Through this connective tissue they can share food. Digested nutrients can be passed throughout the community.
Corals reproduce and spread in three ways: (1)asexually (2)sexually, and (3)regeneration.
1. Asexual reproduction: Corals grow by budding polyps that are arranged in patterns according to their species. Buds form from the oral disks, the area around their mouths, which gradually lengthen out and divide to make two individuals. In brain corals,, the two individuals never completely separate, their rows of polyps all arise from a single, shared dish that becomes a convoluted trench, hence its’ brain-like appearance.
2. Sexual reproduction: Eggs and sperm develop in the stomach walls of the polyps. Waterborne sperm, released through the polyp mouth, are drawn inside other polyps. Eggs are fertilized internally, develop briefly, and then leave the parent as a free-swimming larvae. The timing of this spawning is seasonally rather than constantly. Each larvae carries with it some of its’ parents zooxanthellae and a built-in preference for the proper substrate. The larvae that survive settle after a few days or weeks, attach to an appropriate hard surface, forming a new coral colony.
3. Regeneration: Pieces of coral that break off in a storm drift about and, if they land properly and the piece is big enough, continue growing to form a new colony.
The reef does not always build up, however. Hurricanes destroy reefs, and animals like parrotfish transform hard corals into sand as they feed. However, competition between the different species for space is fierce and destroyed reef is not likely to go unoccupied for long.
Common star coral is one of the Atlantic’s principle reef builders. It grows in massive boulder-shaped heads. A young one, 2 feet square, will already be the basis of an infant patch reef, harboring a few small fishes and invertebrates. Growing at an average rate of 10 millimeters in diameter a year, a single colony may attain a diameter of 15 feet wide and 9 feet high. Such a coral head would be 4-500 years old. A 1973 census of a medium size patch reef 7.5 feet in diameter located off the Bimini Islands yielded 563 fishes of 39 species.
Over 70 species of coral occur in the Caribbean. Corals are divided into 2 categories: Hard, or Reef-Building, and Soft, or Non-Reef-Building. The hard corals are responsible for laying down the structural foundation of the reef, which provides fish habitat and is therefore the basis for the success of the ecosystem. Soft corals provide fish habitat also, but do not build the reef for future generations. The important reef-building corals are Staghorn, Elkhorn and Star Corals. ther hard corals that don’t contribute quite as much toward the long-standing physical structure of the reef are Brain, Pitted, Finger and Pillar Corals, to name a few.
Nowhere else in the Western Hemisphere is there a coral reef ecosystem comparable to the one in Belize for its size, unique array of reef types and luxuriance of corals thriving in such a pristine condition.
What do we do, as visitors, to help preserve the reef at Glover’s Atoll? Belize is one of the few places left where there is a chance to avoid ravaging resources and instead to engender a hallmark of responsible stewardship of this unique barrier reef ecosystem. Glover’s is the richest and least spoiled reef eco-system in the Western Hemisphere, and the Belize government recognized this by designating it a National Marine Reserve. Every visitor has to help to keep it pristine.
Just because coral colonies appear rugged does not mean that they are not delicate. Severe damage does not require a direct hit with a boat anchor. All it takes is a kick from a fin to harm generation of living polyps. Many species of hard corals secrete a layer of mucus that helps to protect the coral. This layer is removed when you touch it, exposing the coral to a wide variety of environmental threats.
Human-induced disturbances introduce artificial stresses into the environment by altering the ecological conditions to which corals have adapted. The principal methods by which corals have been degraded or destroyed are: Direct breakage, asphyxiation by excessive sedimentation (sediment gets stuck in the mucus layer and the coral cannot breathe), chemical contamination of polyps and unnaturally elevated water temperatures. These processes are accelerated by various kinds of development such as urban, industrial, agricultural, shipping and fishing; but tourism also plays a role in exacerbating destructive forces to the corals.
What we can individually do to minimize our impact on the coral reef? Do not touch any coral in any way, including standing on them, or bumping into them. Do not wear gloves. Gloves encourage people to touch the coral. Touching a coral injures its tissues, thus subjecting the corals to invasion and infection. When in a shallow area, try not to kick near the ocean floor. Any stirred up sand can land on the coral and suffocate the individual polyps. Even exhalation bubbles from a snorkel can harm the coral! Tie anchors to dead coral only. Never collect any live corals. Kindly correct others you see who may not be as knowledgeable as you are.