The spectacular coral reefs that grace the peninsula’s east coast are made up of millions of tiny carnivorous organisms called polyps. Individual polyps can be less than a centimeter (0.4 inch) long or up to 15 centimeters (6 inches) in diameter. Related to the jellyfish and sea anemone, coral polyps capture prey with tiny tentacles that deliver a deadly sting.
Reef-building polyps have limestone exoskeletons, which they create by extracting calcium from the seawater. Reefs are formed as generation after generation of polyps attach themselves to and atop each other.
Different species attach in different ways, resulting in the many shapes and sizes of ocean reefs: delicate lace, trees with reaching branches, pleated mushrooms, stovepipes, petaled flowers, fans, domes, heads of cabbage, and stalks of broccoli. Though made up of individual polyps, coral structures function like a single organism, sharing nutrients through a central gastrovascular system. Even in ideal conditions, most coral grows no more than five centimeters (2 inches) per year.
Reefs are divided into three types: barrier, atoll, and fringing.
A barrier reef runs parallel to the coast, with long stretches separated by narrow channels. The Mesoamerican Reef extends 250 kilometers (155 miles) from the tip of Isla Mujeres to Sapodilla Cay in the Gulf of Honduras—only the Great Barrier Reef in Australia is longer.
An atoll typically forms around the crater of a submerged volcano. The polyps begin building their colonies along the lip of the crater, forming a circular coral island with a lagoon in the center. The Chinchorro Bank, off the southern coast of Quintana Roo, is the largest coral atoll in the Northern Hemisphere, measuring 48 kilometers long and 14 kilometers wide (30 miles by 9 miles).
A fringing reef is coral living on a shallow shelf that extends outward from shore into the sea.
The Yucatán’s barrier reef is home to myriad fish species, including parrot fish, candy bass, moray eel, spotted scorpion fish, turquoise angelfish, fairy basslet, flame fish, and manta ray. Several species of shark also thrive in the waters off Quintana Roo, though they’re not considered a serious threat to swimmers and divers. Sport fish—sailfish, marlin, and bluefin tuna—also inhabit the outer Caribbean waters.
Inland, anglers will find hard-fighting bonefish and pompano in the area’s lagoons, and snorkelers and divers will find several species of blind fish in the crystal-clear waters of cenotes; the latter live out their existence in dark underground rivers and lakes and have no use for eyes.
Tens of thousands of sea turtles of various species once nested on the coastal beaches of Quintana Roo. As the coast became populated, turtles were severely overhunted for their eggs, meat, and shell, and their numbers began to fall. Hotel and resort developments have hastened the decline, as there are fewer and fewer patches of untrammeled sand in which turtles can dig nests and lay their eggs.
The Mexican government and various ecological organizations are trying hard to save the dwindling turtle population. Turtle eggs are dug up and reburied in sand on safe beaches; when the hatchlings break through their shells, they are brought to a beach and allowed to rush toward the sea in hopes of imprinting a sense of belonging there so that they will later return to the spot. In some cases the hatchlings are scooped up and placed in tanks to grow larger before being released into the open sea. The government is also enforcing tough penalties for people who take turtle eggs or capture, kill, sell, or imprison these creatures.
The manatee—or the sea cow, as it is sometimes called—is a gentle creature of immense proportions and the curiosity of a kitten. Large numbers of this enormous animal once roamed the shallow inlets, bays, and estuaries of the Caribbean. Images of them are frequently seen in the art of the ancient Maya, who hunted them for their flesh.
In modern times, the population has been reduced by the encroachment of people in manatee habitats along the river ways and shorelines. Ever-growing numbers of motorboats also inflict deadly gashes on the inquisitive surface-feeding creatures. Nowadays it is very rare to spot one; Punta Allen and Bahía de la Acensión have the most sightings.
Manatees are closely related to dugongs, and more distantly to elephants, aardvarks, and hyraxes. Newborns weigh 30–35 kilograms (66–77 pounds), while adults can measure four meters (13 feet) in length and weigh nearly 1,600 kilograms (3,500 pounds). Shaped like an Idaho potato, manatees have coarse pinkish-gray skin, tiny sunken eyes, a flattened tail, and flipperlike forelimbs (including toenails), and prehensile lips covered in sensitive whiskers.
The manatee is the only aquatic mammal that’s completely vegetarian, eating an astounding 10 percent of its body weight every day in aquatic grass and vegetation; it’s unique among all mammals for constantly growing new teeth to replace those worn down by the manatee’s voracious feeding. Posing no threat to humans or other animals, and ecologically important for their ability to clear waterways of oxygen-choking vegetation (to say nothing of being exceedingly adorable), manatees nevertheless remain highly endangered in the Yucatán and elsewhere.
© Gary Chandler & Liza Prado from Moon Yucatán Peninsula, 9th edition