NATURE

SUBTERRANEAN MARVELS

The Spanish conquistadors were amazed to discover that the Yucatan Peninsula in Mexico had no rivers, and only a few small lagoons. They wondered how the numerous Maya, living in the countless cities and small villages, could survive on this dry and harsh terrain. The Yucatan Peninsula made up one fifth of the territory inhabited by the Maya people, yet it scarcely rained in the region, and its periodic droughts were long and intense.

By Juan José Morales

The Maya were able to survive droughts, and even flourish, because they used an unusual system of natural wells for their water supply. The northeastern Yucatan has approximately six thousand such wells, which gave the Maya access to an extensive system of underground rivers. The Spanish colonials named the sinkholes cenotes, from ts'onot or dzonot, the native words for the the natural wells.

Though cenotes are not unique to the Yucatan Peninsula, they are fairly uncommon geological formations. There are a precious few in Florida (United States of America) and Cuba, but nowhere else in the world is the land so honeycombed with underground rivers just bellow the land's surface as is the Yucatan. See how a cenote is formed.

Cenotes vary considerably in shape and size; some are tiny and others gigantic. One of the most famous is the Sacred Well at Chichen Itza, a Maya ceremonial center in the Mexican state of Yucatan. Shaped like a slightly oval well, it is fifty-eight meters in diameter, with vertical walls that measure twenty meters from the ground's opening to the water's surface. It's depth is eleven meters of water with a twelve meter layer of mud underneath.

Some cenotes form inside coastal lagoons, acting as fresh water feeders that lower the salinity levels of the sea water. Most can be easily recognized, like the enormous Cenote Azul de Bacalar, located in the state of Quintana Roo. However not all can be seen from the surface. Some are discovered because their depth is greater than the lagoon's. Diving expeditions often reveal that there are large holes in the mantle of hard rock situated under the lagoon's muddy bottom.

Saltwater from the Caribbean and the Gulf of Mexico seeps inland into the peninsula. Because of this, many cenotes near the coast have a layer of fresh water floating on top of a layer of salt water. A swimmer or diver can recognize this curiosity when the water, after being disturbed, looks as if it were mixed with oil to produce an iridescent film.

Another fascinating feature found in many cenotes is that regardless of being flooded with water, stalactites and stalagmites are found. Stalactites and stalagmites are formed when drops of water partially evaporate before or after they fall from a cave ceiling, leaving small amounts of mineral salts. Over centuries, the accumulation of mineral salts forms stalactites which hang from the roof, and stalagmites which rise from the floor like pillars

These rock crystals can form in partially empty caverns where water filtrates down and drops from the ceiling. But it can not happen in completely inundated spaces such as cenotes. How is it possible for their to be cenotes with stalactites and stalagmites? These formed over more than fifteen thousand years ago, during the last ice age. The sea level in the Caribbean was seventy five meters lower then than it is today. The subterranean waters that flowed to the sea had an equally lower level and what today are inundated cenotes were then air filled grottos. Latter, when the climate changed and the the ice glaciers melted, the oceans ascended, and with them the level of the subterranean rivers also ascended. The ancient caves, with their stalactites and stalagmites, were inundated. See how the cenotes are connected.

As a result of the changing sea levels and also the geological movements that have lifted and continue to lift the Yucatan peninsula, cenotes are the habitat of unusual animal life forms. Principally cenotes house creatures whose ancestors were marine life and later, trapped in the depths of the earth, evolved and adapted to life in fresh water and darkness.

One of the most abundant and well-known life-forms is the blind white Dama (Ogilbia pearsie). This small fish does not have eyes nor skin pigmentation, which gives it a rare, white iridescent glow that turns pink when light hits it. These strange fish only exist in the cenotes of Yucatan peninsula. The blind eel (Ophisterno infernaleis), which is also exclusive to this region, grows a length of up too seventy centimeters and lives buried in the mud. Another eel that lives in the cenotes is the Synbranchus marmoratus. These grow a length of one and a half meters and have very small eyes. However, these eels are not unique to the Yucatan peninsula, having a wide range of habitats that extend from Mexico to Peru and Argentina and from grottos to open waters.

Various species of shrimp, as well as other small invertebrates that are either blind or have tiny eyes, inhabit cenotes. A curious detail of many of these creatures is that regardless of living isolated from the outside world, in complete darkness, they follow what is called a circadian rhythm: biological cycles recurring at twenty-four hour intervals, as if they could perceive the succession of day and night.

In the later part of the 20th century, research of cenote fauna was begun. The studies were made possible in part by the boom in cave diving, which has allowed the exploration of once inaccessible sites. Daring divers have discovered new species such as the Speleonectes tulumensis, name in Latin that signifies "the caveman of Tulum". This animal was discovered in a cenote next to the Maya archeological site of Tulum. Later, the same species was found in Belize.

The Speleonectes tulumensis, which is blind and colorless, is a type of primitive crustacean, relative of the crab. It has numerous legs like a centipede which it uses as oars for swimming. The Speleonectes tulumensis is between two and a half to three centimeters long. It lives in cenotes close to the sea, in the saltwater underneath the freshwater. Most fish would die in such an environment, the water being mostly void of oxygen. The Speleonectes tulumensis, does not just live well in such water, but when transferred to oxygenated water it enters in to frantic activity, ceaselessly swimming until it consumes itself from exhaustion.

In addition to these unusual animals, many fresh water fish live in cenotes as well as in rivers and lagoons. The two most abundant species are the Bagre (Rhamdia guatemalensis) and the Mojarrita (Cichlasoma urophtalmus). The Bagre is a whiskered fish that grows ten to fifteen centimeters long and exists throughout Central America. The Mojarrita reaches ten centimeters and is known for the dark vertical stripes across its body.

The ancient Maya had different uses for the cenotes, some were exploited as water supplies while others were exclusively designated for ceremonial ends. The Maya honored gods like Chaac, the rain and water god, at the sink holes as well as considered cenotes the entrance to the underworld. An example of this can be found in Chichen Itza. It's inhabitants used the cenote Xtoloc as a daily life water source, while the Cenote Sagrado was the grounds for human sacrifices; virgins were hurled into the cenote from an altar placed on the edge. See what usage the Maya give cenotes.

Today, cenotes are used principally as tourist attractions, especially in Yucatan and northern Quintana Roo. In some cases as part of large eco-touristic centers, others as specialized sites for cave diving, and the rest of the time as small family enterprises in farmer communities. In this way cenotes, those subterranean marvels, are taken advantage of by the heirs of the people, that more than two thousand years ago, to part of the rise and life of the villages of the northern Mundo Maya.

 
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