"Es el móvil océano gran espejo
donde luce como adorno sin igual

el Terruño Borincano que es reflejo
del perdido Paraíso Terrenal."
Virgilio Dávila (1869-1943) and Braulio Dueño Colón (1854-1934), La Tierruca

"One Love, one Heart.
Let's praise the Lord and feel allright!
Let's get together and feel allright!"
Robert Nesta (Bob) Marley (1945-1981), One Love

Enya, Orinoco Flow

Trunk Bay. Virgin Islands National Park, Saint John, United States Virgin Islands.

The Neotropical Kingdom

    Biologists and biogeographers have divided the dry land areas of planet Earth into nine major regions which are defined by the groups of ecologically interconnected organisms that live within them. Their limits are marked mainly by natural barriers like oceans, deserts, high mountain ranges, and latitudinal climatologic boundaries all of which are frequently insurmountable to many species of plants and animals.

    Although these "biogeographic regions" are generally well-defined, they are far from being perfectly so. Not only may the transition between each and the next occur over tens to even hundreds of kilometers, but many organisms that are typical of a region often "spill over" deep into adjacent ones. This they do temporarily (as happens during seasonal transcontinental migrations), through naturally established and viable populations, or by means of man-made introductions.

    Such regions of the World can in turn be divided into sub-regions or "biogeographic provinces", each characterized by subsets of organisms requiring increasingly specific ecologic conditions to survive, or set apart by natural barriers internested within the larger ones.

    The oceans of the World can be similarly divided, though enough data to define clear boundaries is lacking at the present moment. (The Caribbean Sea may indeed be one of such distinct oceanic bio-regions).

    The nine primary terrestrial biogeographic regions of the World are:

        - the Antarctic: Antarctica, its surrounding ice-shelf, and its nearby islands

        - the Western Palearctic: Eurasia (west of the Ural Mountains and India), including the Azores, the Cape Verde, and the Canary islands, and

          northern Africa to the southern limits of the Saharan Desert

        - the Eastern Palearctic: Eurasia east of the Ural Mountains, the Caspian Sea, and Pakistan, except for the Indo-Malayan Region

        - the Afrotropical: Africa south of the Saharan Desert, together with Madagascar and its satellite islands, and the southern limits of the Arabian Peninsula

        - the Indo-Malayan: the Indian subcontinent and south-eastern Asia, as well as the islands on their continental shelf (Sri Lanka, Java, the

          Celebes, Sumatra, Borneo, the Philippines, etc.)

        - the Australasian: Australia and its continental islands (New Guinea, Tasmania, etc.)

        - the Micronesian: most islands in the Pacific Ocean (sometimes combined with the Australasian Region)

        - the Nearctic: most of North America together with Bermuda and Greenland

        - and, finally, the Neotropical Biogeographic Region, which extends southward from the Straight of Tehuantepec, in southern Mexico, through the whole of Central and South America, and includes several groups of oceanic islands like the Antilles in the Caribbean Sea, the Galapagos in the eastern Pacific Ocean, and the Falklands in the southern Atlantic Ocean.

    Within the Neotropics we find an extensive variety of ecosystems, including the driest region on Earth after inner Antarctica, namely Chile's Atacama Desert, as well as the largest continuous rain forest, in the enormously vast Amazonia. Here are found the loftiest mountains in the Western Hemisphere, which are also among the youngest in the World: the Andes of perpetual snows, with 7365-meter Mount Aconcagua as the summit of the Americas. Extensive littoral mangrove swamps encircle the West Indies and the Caribbean coasts of South America. Alpine ecosystems are found on the higher slopes of the tallest mountain ranges, with cloud forests on their piedmont, further down. A cold climate prevails in Tierra del Fuego, the southernmost, sub-Antarctic tip of South America, and in the Falkland Islands, east of there. The soils of much of the western edge of South and Central America were given birth by the chain of numerous volcanoes of the region which, continuing up western North America, snakes south again along eastern Asia to form the Ring of Fire that encircles most of the Pacific Ocean. Some of the highest mountains of the entire region are among such fickle giants, like Colombia's Nevado del Ruiz and the massive trio of Orizaba, Popocateptl, and Iztaccihuatl, in southern Mexico. The isolated Galapagos Islands are likewise of volcanic origin. In southern Venezuela, northern Brazil, and the Guyanas, sandstone plateaus called "tepuis", some higher than 3000 meters, tower above the surrounding lowland rain forests. The basin of the Orinoco River has wide expanses of freshwater swamps and flooded forests. The enormous grassland prairies of the Argentine and Paraguayan pampas cover much of the southern half of the South American continent. Mesoamerica and the Antilles have extensive montane rain forests, while dry forests and thorny scrub cover much of their leeward lowlands. Coastal rain forests extend through eastern Brazil, with chaparral forests further south and west. And the Neotropical scenario would not be complete without mention of the planet's most powerful watercourse: the immense River Amazon. Second in length only to Africa's Nile, the 6280 kilometer-long Amazon is so wide in some areas, that when one navigates on a ship through its middle, its shores are beyond sight. It carries more water than the next ten largest rivers combined, and a full one fifth of all freshwater in the World. Through its tributaries it receives water from 40 percent of South America, comprising the most extensive drainage system known. For most of its length it is only a few meters above sea level, and when the Atlantic's high tides reach its delta, the sudden water-rise of up to four and a half meters is sometimes noticeable hours later, 800 kilometers upstream. During rainy seasons, it overflows it banks so extensively that it floods hundreds of thousands of square kilometers of lowland rain forest. Its outpour is so gargantuan that 320 kilometers from its mouth, well within the Atlantic Ocean, one would still swim in fresh water.

    Finally, the Neotropical Realm constitutes the richest and most complex region on planet Earth in terms of organic life.

The Antillean Islands

    Every year millions of persons visit the West Indies. They come mostly from North America and Europe, and many seek a warm beach where to escape from the cold winters of the high northern latitudes. The casual visitor to the Caribbean is often enthralled by the smells and tastes of the local cuisines and overpowered by the ambient humidity that pervades the lowlands of the islands year-round. Sadly, these same visitors seldom realize that beyond the surrounding city and tourist resort rhythms of salsa and merengue, reggae and wawanco, soca and calypso, another world awaits... one that most do not even imagine.

Origins

   The islands of the Caribbean Basin have long been considered a part of the Neotropics, and as such I discuss them here. However, some authors regard the basin to be unique enough in its biota to form a separate entity and, thus, a ninth to be added to the list above: the Caribbean Biogeographic Region, comprising the West Indies and Central America south of the aforementioned Isthmus of Tehuantepec. This belief stems from the fact that at least some groups, like the Greater Antillean and Bahamian birds and reptiles and those of Mesoamerica are generally more closely related among themselves than to those found anywhere else. (Some authorities include in the Caribbean Region the southernmost reaches of the Florida peninsula and its cays, due to the strong Antillean influence that they exhibit).

    At the very least, the Antilles indeed form a distinct Neotropical province on a par with many others within the region.

    The West Indies, or Antillean Archipelago, are an aggregation of thousands of islands, cays, and islets. They range in size from small rocks barely emerging from the waves to Cuba, which at 110860 square kilometers is almost as large as the rest of the Caribbean islands put together, or about as large as the state of Pennsylvania, in the United States of America. The archipelago is found east of Mesoamerica and, as a whole, halfway between North and South America.

    The Antilles are typical oceanic islands, in that they do not lie on the submarine platform of a continent. Possibly, they have never been physically connected to any of them, even during glacial maxima, when sea levels are at their lowest as more water relocates as ice around Earth's poles.

    If one were to see the entire geological history of the Antilles squeezed into a few minutes, they would probably look like a group of amoebas crawling on the surface of the ocean. Through eons of time, these islands have repeatedly expanded and contracted their areas, split, fused, split again, and shifted shapes and their relative positions. In fact, the Antilles (or at least the Caribbean Tectonic Plate) might have originated west of the Americas, in the Pacific Ocean, perhaps even close to the present Galapagos Islands' volcanic hot spot. From there, they migrated eastward to their present location. After that, the emersion of Central America isolated the modern Caribbean Sea from the Pacific Ocean and made it a portion of the Atlantic Ocean, instead. (The Caribbean is effectively a mediterranean sea, since it is "surrounded by lands" - in its case by the American continents and the Antilles themselves).

    The theory according to which the Caribbean Sea was once contiguous with the Pacific Ocean is supported in a rather surprising way. At its deepest reaches fish and other organisms are found which closest relatives are not found in the Atlantic Ocean, but in the abyssal plains of the Indo-Pacific.

    As an alternative to the scenario described above, at least the Greater Antilles may be Central American blocks which became detached from the continent and migrated east. This hypotheses is partially based in the Mesoamerican relations of a number of reptile, freshwater fish, and insect taxa now found in the Greater Antilles. In this case, the Lesser Antilles may have emerged later, through volcanic phenomena caused as the leading (eastern) edge of the Caribbean tectonic plate slides over the Atlantic Basin plate, melting it as it pushes it down. The subducted molten material of the Atlantic abyssal plain would then erupt upwards, the lava solidifying into what are now the Lesser Antilles.

    The West Indian Neotropical Province is in presently divided into three main sub-provinces: the Greater Antilles, the Lesser Antilles, and the Bahamas.

    The modern West Indian map is dominated by four large and mountainous islands: the Greater Antilles. From west to east, they are Cuba, Jamaica, Hispaniola, and Puerto Rico. Long before they neared their present locations, their shapes and extensions were already influenced by a mixture of volcanism and the uplifting of the northern border of the Caribbean tectonic plate, as the heavier North American plate (which includes the Bahamas and most of Cuba) slowly sinks, even now, under it. The oldest geologic materials that have been continuously above water in the Caribbean are found in what are today Cuba and Puerto Rico. Parts of both may date back to the late Jurassic Period.

    Cuba is the largest of the Antilles. Until a relatively recent past its lowlands were flooded by the ocean, being thus fragmented into as many as three islands laying on the same insular bank. It has vast littoral and inland plains, as well as mountain ranges in several regions. Areas covered in limestone are found especially in the western end of the island. Extensive groups of cays are found off both its northern and southern coasts, and the Isle of Youth is it largest offshore island. The Cuban insular bank may contain the most complex and varied biota in the Caribbean Basin, rivaled in that sense only by the Hispaniolan bank.

    Hispaniola (shared by the Dominican Republic and Haiti) might itself be the most geologically complex of the Antilles, as it is actually composed of a northern and southern paleoislands with separate origins (that is to say: each one was on its own insular platform, at first). The southern island collided with the larger northern one during the Miocene, and today they are fused together along the Neiba Valley-Cul de Sac Plain. Hispaniola's largest satellite island is La Gonave, engulfed by the northern and southern peninsulas of Haiti. The highest point in the West Indies, 3175 meters-high Mount Duarte, is to be found in the Central Mountain Range of the Dominican Republic. Other important mountainous systems are the limestone Bahoruco Mountains-Massif de la Selle, the Massif de la Hotte, and the Neiba Range. Indeed, Hispaniola possesses the highest mountains in the Americas, outside the Andes and the Rockies. The lowest point in the West Indies is in the same island: the Lake Enriquillo Depression, at about 45 meters below sea level.

The Bahoruco Mountains, in southwestern Hispaniola, are a limestone massif that rises

to more than 2,500 meters from the coast over a small horizontal distance, thus having a very steep gradient.

    Both Jamaica and Puerto Rico are smaller and geologically simpler than their two much larger neighbors and, while they themselves are similar in size, their origins are quite different.

    Although it was probably emergent during the late Cretaceous or early Paleocene, Jamaica was later completely submerged. In its present state it is the youngest of the Greater Antilles, perhaps being above water only since the middle Miocene, about 16 million years ago. Among those of the Caribbean, its Blue Mountains are second in height only to some in Hispaniola. It also has extensive regions of limestone in its north-western quadrant, as well as a tall limestone range in the east, the John Crow Mountains. It's submerged insular platform is the narrowest of the Greater Antilles, and it has but a few tiny offshore cays.

Montane valley. Blue Mountains, east-central Jamaica.

The eastern reaches of the John Crow Mountains, seen from near Point Morant., eastern Jamaica.

    Puerto Rico was part of the northern Hispaniolan paleoisland before it separated and moved further east around 15 million years ago, during the Miocene. After that time much of it was submerged before reemerging about 3 million years later. Like Jamaica, it has a mountainous backbone and a limestone belt. It has as well isolated mountain massifs near its eastern tip, namely the Luquillo and Pandura ranges. Similar to Hispaniola, its tallest mountains are near the center of the island. Among the Greater Antilles, its submerged insular platform is the most extensive in proportion to the emergent area and it has numerous satellite islands and cays, largest of which are Culebra, Vieques, and the northern Virgin Islands. That means that if the size of the insular bank and, thus, the extension of the biogeographic unit are considered, the third largest island in the Caribbean turns out to be Puerto Rico, and not Jamaica. However, that is not obvious if one looks at a normal map, because almost half of Puerto Rico is today under a mere 100 meters of sea water.

Seen from far out at sea, the central mountains of Puerto Rico run almost the entire length of the island.

     In a few places in the Greater Antilles the mountains reach the shores, where they rise straight from the sea to great altitudes. Another product of the collision between the North American and Caribbean tectonic plates is a geologic subduction zone which features the lowest point beneath the Atlantic Ocean: the 8400 meter-deep Puerto Rican Trench, located north of both the island that gives it its name and of Hispaniola.

    Although no active volcanoes remain in the Greater Antilles, reminders of a distant past are seen in the sulfuric hot springs of some places like Coamo, Puerto Rico. Also, volcanic rocks are found in many regions of these islands.

Ancient, eroded granite comprises much of the geological material in the backbones of the Greater Antilles.

Tetas de Cayey, Cayey Mountains, south-eastern Puerto Rico.

Immense granite boulders lie on top of one another,

forming marine grottoes in The Baths National Park, Virgin Gorda, British Virgin Islands.

They are remains of the volcanic past of these easternmost islands of the Greater Antillean complex.

Photographs may fail to convey their true size. The "small" flat-topped rock in the first image is almost three meters tall.

    To the north and north-west of the Greater Antilles lies the Bahamian Archipelago. Low-lying limestone and fossil-coral islands, perhaps connected at times with the Cuban paleoislands, the Bahamas are generally small, although Andros Island (itself an archipelago) is about the size of the Puerto Rican mainland, if one counts the numerous sea channels that intersect it. In accordance with their location and the prevailing oceanic currents, much of the biota of the Bahamas derives from, or is shared with, the Greater Antilles, particularly Cuba and Hispaniola.

    In spite of these close biogeographic ties to the Greater Antilles, in fact the deeply dissected Bahamian Platform rests on the North American Tectonic Plate. (That is to say, the Bahamas, together with Cuba, are geologically North American islands). It is to this platform that the northern boundary of the Caribbean Plate eventually became "sutured", effectively preventing any more subduction. That seems to be the reason why volcanism ended long ago, in the Greater Antilles.

The Bahamian archipelago consists of an enormous number of flat coral and limestone islands. None have anything that could be considered as "highlands".

Taken together, they comprise an important and extensive biogeographic sub-province within the larger West Indian region.

Aerial views of Andros Island, Bahamas.

(Photographs courtesy of Mr. Joseph Burgess).

    To the east and south-east of the four major land masses are found the Lesser Antilles, a double arc of small islands that almost reaches Venezuela. Most of them emerged from the sea through volcanic activity. In spite of their limited size, many of them are steeply mountainous and, indeed, each island is but the summits of a small mountain range rising from the Caribbean and Atlantic abyssal plains.

    In spite of the apparent simplicity of the Lesser Antillean archipelago, the group is actually a double geological entity. An outer arc of older, eroded material extends from northernmost Sombrero, and includes Anguilla, Saint Bartholomew, Saint Martin/Sint Maarten, Antigua, Barbuda, the eastern half of the double island of Guadeloupe, Marie Galante, south to the eastern half of Martinique. These outer arc is partially composed of sedimentary rocks, including limestone.

    The inner and younger arc extends from Saba, in the north, and includes Saint Christopher, Nevis, Redonda, Montserrat, the western half of Guadeloupe, Dominica, the western half of Martinique, Saint Lucia, Saint Vincent, and south to Grenada. These islands, unlike those of the outer arc, are almost purely volcanic.

    These are the Lesser Antillean islands that have both dormant and active volcanoes. The recent eruptions of the Soufriere Hills in Montserrat and, in a recent past, of Martinique's Mount Pelèe and Saint Vincent's Mount Soufriere are a reminder that many of the Lesser Antilles are, geologically, very much alive and still growing.

    In fact, a good number of places in these islands have the name "soufriere" applied to mountains, thermal springs, and even villages. The French term means "sulfuric vent", and another nuance is "suffering".

    Of course, volcanoes frequently destroy even as they create. As an interesting - if sinister - historical note, in 1902 the then capital city of Martinique, Saint Pierre, earned the sad distinction of becoming the "Pompey of the Caribbean". Around 8:00 AM on Thursday, May 8th of that year Mount Pelèe awoke after centuries of slumber, and erupted with murderous violence. The ensuing pyroclastic avalanche took all of five minutes to incinerate the city's entire population of thirty thousand. Only one person escaped the wrath of the hulking giant: the sole prisoner in the local jail, which walls protected him from the surrounding devastation. He was scheduled to be executed by hanging... on that same day.

    The volcanism of the inner Lesser Antilles is also noticed in a more indirect way. Rising steeply from the ocean's floor, many of these islands have little of what could be called "beaches". The underwater insular platforms are very narrow, and plunge to great depths just a short distance from the shore. Since the symbiotic algae that coral polyps need to thrive cannot survive below depths of a hundred meters or so, there are few coral reefs surrounding the islands. Over thousands of years, dead coral skeletons are pulverized by wave action, and become the alluring golden and white sand beaches that are so common in the Greater Antilles and the Bahamas. But having no coral reefs to provide for these, many littorals of the younger Lesser Antilles are covered in a coarse gray or black sand that is really ground basalt. Perhaps not as attractive to the human eye but still very interesting, indeed.

    The Lesser Antilles have traditionally been segregated, as well, into two artificial groups according to their mutually relative positions on navigational charts. The Windward Islands run from Dominica south to Grenada. The Leeward Islands extend from Guadeloupe, northwards to, but excluding, the Puerto Rican insular bank.

    A small number of West Indian islands do not belong to any of the three main archipelagoes already described, even as they are integral parts of the biogeographic subprovince. Among these, the Cayman Islands, south of Cuba, as well as Saint Andrew, Providencia, and others close to Central America (though not on the continental shelf itself) are above-water geologic ridges in the middle of the Caribbean Sea. Barbados, east of the Lesser Antilles, is an emergent limestone plateau situated beyond the eastern, leading edge of the Caribbean tectonic plate. However the character of its biota is decidedly Lesser Antillean, geologically it is not a Lesser Antille but in a class all by itself. Its origins are quite obscure, and it may be more closely tied to the South American continent than with the rest of the West Indies.

    Finally, some islands that lie within the geographic boundaries of the Caribbean Sea do not belong to the Antilles, either geologically or biogeographically. That is to say: not only are their geologic origins unrelated to theirs, and their biota have very little to do with those of the West Indies. For example, the Dutch "Antilles" of Aruba, Bonaire, and Curaçao, off the Caribbean coast of Venezuela, are oceanic in character and their biota is mainly South American and highly endemic, if depauperate. Margarita, Trinidad, and Tobago, east of them, are continental islands (as opposed to oceanic). They are located on the South American continental shelf - and thus are satellites of  that continent - might have been united to it during glacial maxima, and share most of their biota with it.

Geography

    The environments of the Antilles are deeply influenced by the climate, which itself has changed drastically, time and again, during the millions of years of their existence. Certainly the abundant rain prevalent during many periods have contributed to erode mountains, rivers have formed valleys, and the pounding waves of the sea have cut coastal cliffs and caves. During glacial ages, at least some areas of the Greater Antilles were covered in glaciers which carved deep inner plains and valleys and dramatically influenced the distribution of many organisms, even to this day.

The Yabucoa alluvial valley, south-eastern Puerto Rico.

The rivers that meander through valleys like these are what creates them. Sadly, such lowland areas are mostly

denuded of natural vegetation nowadays. They have been cleared for crops, pasture, and urban development.

The Lajas alluvial valley at dawn. South-western Puerto Rico.

    The variety of topographies found in the West Indies, combined with the prevalent northeast-southwest wind patterns, allow the islands to have widely dissimilar vegetative associations, sometimes within mere kilometers of one another. Generally, the windward (eastern and northern) sides of the Greater and Lesser Antilles support tropical humid and rain forests. The leeward sides of the islands, in the rain shadow of the mountains, are dry - sometimes being true deserts - and are occupied by xeric forests, cactus scrub, and savannas. Such is the case of the coast of the province of Guantanamo, in south-eastern Cuba, the Neiba-Cul de Sac Valley of south-central Hispaniola, the coastal region between Salinas and Cabo Rojo in south-western Puerto Rico, and the Hellshire Hills of south-eastern Jamaica. The summits of the tallest mountains, especially in Cuba, Hispaniola and Jamaica, might experience winter temperatures below water's freezing point and support temperate forests, including pine woods in the first two.

    Most forests in the West Indies are in a perpetual state of succession and renewal. The reason for this arises from the very waters that surround the islands and from the mechanisms of our planet's cooling system. Every year, between early summer and late autumn, the tropical Atlantic Ocean spawns a number of meteorological disturbances. They begin as tropical depressions off eastern Africa, and usually move westward, and as they travel over the surface of the ocean, the warm waters continually fuel their engines. They gain in size and strength, and eventually begin to rotate around a vortex called the "eye", thus turning into "tropical cyclones". Once their wind speed reaches 120 kilometers per hour they become what are among of the most feared and awesome of natural phenomena: hurricanes.

    Their name derives from the Greater Antillean Taíno Amerindian term "huracán" (pronounced "uh-rah-KAN"), meaning "strong wind". Not surprisingly, by that word they also used to name the god of evil of their mythology. Some hurricanes may attain a diameter of 1000 kilometers. With wind speeds as high as 320 kilometers per hour, and often accompanied by torrential rain, these most powerful storms on planet Earth can wreck havoc on plant, animal, and human life alike. Names like Andrew, Frances, Gilbert, Hugo, Ivan, Jeanne, Katrina, and Marylin remain forever seared unto the collective memories of the peoples who came to know them closely.

    As with tsunamis, earthquakes, and volcanic eruptions, the full strength of a hurricane defies description. The unnerving fury of its vortex has to be experienced to be apprehended by one's inner self.

Around midnight between September 15th and 16th, 1995, hurricane Marylin's vortex went straight over the island of Saint Thomas, one of the United States Virgin Islands. The 216 km./hour winds raged for almost 12 hours. The winds were even stronger over the hills, due to a funneling effect as they swept over the topographic inclines. They, and the storm-surge that accompanied the eye, sent 3 meters of sea water through the capital city of Charlotte Amalie, destroying buildings, overturning cars, and hurling boats onto the roads. Eleven people lost their lives, some of them because they decided to ride the storm in their ships, overnight. Others were pummeled to death by flying debris as they left their unsafe homes in the middle of the night. Marylin was the worst natural disaster to occur in the Virgin Islands in almost 75 years.  (By the way, in the upper photograph, the yellow building with the gray roof, on the hill in the distance, was my parish church: ethnic-French Saint Anne's). The day before hurricane Marylin went over Saint Thomas, about 70 sailboats and yachts were anchored in or near Charlotte Amalie's Bay. Next morning, not one was to be seen, there. They were all either underwater or parked on the city's roads. In some places, the winds piled up cars on top of one another. Hundred of thousands of kilograms of dead seaweed and fish rotted on the streets for several days. With the proper attitude, and without in any way trivializing human suffering, experiencing a hurricane's wrath approaches the religious. (As some saints would say, "if such is the power of the creature, what must the Creator's be.")

Hurricane Marylin's winds stripped the leaves of most of the plants in Saint Thomas. For weeks, the entire island had a brownish color, when seen from a distance.

Because everything to the highest altitudes was covered in sea salt, the vegetation and animals were subjected to additional stress from which they took several months to recover. Several species of birds and butterflies disappeared for months, then to slowly reinvade from neighboring islands.

Hurricane Ivan went over the island of Grenada on September 2004.

Many building, like the Catholic Cathedral of the Assumption of Mary, were destroyed by the savage winds.

Years after the passage of hurricane Marylin through the Virgin Islands, the white skeletons

of mangrove trees stand in testimony to the wind's fury, months after the onslaught.

Mary Point Pond, Virgin Islands National Park, Saint John, United States Virgin Islands.

Montane tropical rain forests, central Grenada, Lesser Antilles.

These forests are still regenerating one year after the onslaught of hurricane Ivan.

       Almost every Caribbean island is hit squarely by one of these gigantic tropical storms every 10 to 15 years, on the average. The result is that Caribbean tropical forests have a somewhat different structure than those in South and Central America. While such - and some are truly monstrous - cyclonic systems can ravage a forest beyond recognition, the fact is that these catastrophes help create niches for numbers of plant and animal species that would otherwise be unable to subsist indefinitely in more stable conditions. So, and ironically, hurricanes contribute to maintain the peculiar biodiversity of West Indian terrestrial ecosystems, since many organisms there evolved to cope with them.

    However, hurricanes are also one of the reasons why small and flat Caribbean islands have comparatively few species of organisms, especially of the non-flying kind. It is not only that having smaller areas, lack of mountains and, thus, fewer available habitats limits their capacity to sustain more complex communities. Hurricanes never devastate in their entirety large islands, like the Greater Antilles and the largest of the Lesser Antilles and the Bahamas. In them, many animals will usually find refuge in the few relatively untouched areas, after the storm. But on smaller, low-lying islands like Anegada or Barbuda, and on tiny cays, a hurricane can indeed wipe out entire populations overnight through the effects of wind and sea water. Any survivors of the storm might remain so stressed, and for so long, by either lack of habitat or nourishment or by excessive sunlight due to the defoliation of the trees, that they might not survive, anyway.

Icacos Cay and Palominitos Cay, both off the eastern coast of Puerto Rico.

Small cays and islets in the Caribbean have extremely depauperate terrestrial biota, due to limited variety of

habitats and the effects of hurricanes, which can totally flood them with seawater several times every century.

Both off these cays are fringed by coral reefs, the second most complex type of ecosystem on Earth, after tropical rain forests.

Small cays may harbor very localized endemics. This is Carrot Rock, in the British Virgin Islands.

(Photograph courtesy of Dr. Luis O. Nieves).

Saba Cay, off south-western Saint Thomas, United States Virgin Islands.

Inner and Outer Brass islands. Off northern Saint Thomas, United States Virgin Islands.

Caja de Muerto is a small island off the southern coast of Puerto Rico.

Protected as nature reserves, small land masses like this one can serve as refuges for organisms threatened in the main islands.

Mona Island.

Although politically being part of Puerto Rico, it is actually closer to Hispaniola.

This impressive, arid plateau of limestone isolated in the Caribbean Sea is home to a large number of endemic organisms.

(Photograph courtesy of Mr. Joseph Burgess).

Monito Cay, off northern Mona Island.

(Photograph courtesy of Mr. Joseph Burgess).

The Maria Islands, off south-eastern Saint Lucia, Lesser Antilles.
These are the last refuge of several Saint Lucian endemic reptiles now extirpated from the main island due to predation by exotic mongooses.

    Hurricanes and volcanic eruptions aside, it is precisely the stability of the temperatures and humidity in the tropics in general what allows for the immense wealth of life in them. Not having to cope with drastic changes in the amount of abiotic factors such as sunlight, heat, and rainfall, permits organisms to more constantly and exclusively deal with other organisms. They invest more energy in surviving interactions and in coevolving with each other in ever-changing  relationships of predator and prey, of parasite and host, as well as constant chemical warfare and competition for shelter, food, or mates. They strive to make ever better use of their tri-dimensional territories. Doing all this, and being able to remain active and reproduce for longer periods of time, unbroken by hibernation and aestivation, grants living beings greater chances to speciate. In tropical environments the result of such stability - and the continuous activity and evolution it provides for - is an exponential increase in the number of species as compared to Earth's temperate forests and tundras, which are subjected to far more drastic climatic changes.

    In some coastal areas of the Antilles the wind shapes the shifting sands into dunes. Such geologic formation, as well as the ecosystems that depend on them, have disappeared from extensive regions due to development and other human-related reasons. In other places are found salt flats formed by the evaporation of salt water reaching inland after a storm or unusually high tides or deposited by rivers with no exit to the sea.

    The seemingly lifeless rocky shores of some islands, made of limestone, sandstone, or granite are a haven for diverse organisms both above and below water. Such are favorite hunting and perching grounds for pelicans, tropicbirds, gulls, and other avian species.

    Where limestone reaches the sea, being a rather soft rock, it is often cut into high cliffs and pinnacles. These provide nesting places for a number of marine and terrestrial birds.

    The Greater Antilles, as well as some of the Lesser and many of the Bahamas, have extensive areas of limestone, crevassed and hollowed-out by sink-holes and caverns, some of immense proportions. The Camuy and Encantado rivers, in northern Puerto Rico, are partially subterranean water courses passing through cavern systems 16 and 18 kilometers long, respectively.

    The Stygian darkness of these underworlds maintain their own ecosystems, many of them surprisingly rich and complex. It is not only the bats, but also shrimp, fish, whip spiders, onycophores, tarantulas, crickets, snakes, and many others who call these places "home".

Subterranean streams and waterfalls in Yuyu Cavern. Ciales, central Puerto Rico.

Water is the main builder of limestone caverns. Clara Cavern, Camuy Cavern Park, Camuy, north-western Puerto Rico.

Dripping water leaves deposits of calcite in many limestone caverns. Isabela, north-western Puerto Rico.

Some of the formations created by the action of water on rock have an almost organic appearance.

It is a strange sensation one gets when expecting some to be pliable and spongy,

and then realize they are rock-hard and abrasive to the touch.

Yuyú Cavern, Ciales, central Puerto Rico.

Near the entrance of caves and caverns, mosses and other organisms

adapted to low light levels can be found on the walls.

Cathedral Cavern, Camuy Caverns, Park, Camuy, north-western Puerto Rico.

Clara Cavern, Camuy Caverns Park, Camuy, north-western Puerto Rico.

The "boulder" in the fourth photograph from left to right is actually the largest stalagmite known to date.

A cavern in Cabo Rojo, south-western Puerto Rico. Locally known as "Cueva de la 22", it harbors tens of thousands of bats.

The brown stains on the rock faces are caused by bat guano.

Caverns, Mona Island.

Mona is a small island located between Puerto Rico and Hispaniola. Composed completely of limestone, it is hollowed-out by nummerous caverns.

(Photograph courtesy of Mr. Joseph Burgess).

When the roof of a cavern collapses, a geological formation called a "sinkhole" is created.

This is the entrance to a sinkhole, seen from below.

Near Clara Cavern. Camuy Caverns Park, Camuy, north-western Puerto Rico.

A view from the rim of Tres Pueblos sinkhole. Camuy Caverns Park, Camuy, north-western Puerto Rico.

Snail fossils embedded in the limestone.

Cueva de la 22, Cabo Rojo, south-western Puerto Rico.

    The abundant orographic ("caused by the mountains") rainfall typical of Antillean highlands contributes to the formation of streams and waterfalls, especially on the windward side of the mountain ranges. As the trade winds pass over the towering backbones of the islands, water vapor from the Atlantic Ocean and the Caribbean Sea condenses and the resulting clouds dump billions of liters of water every year. Some of the mountains in the Lesser Antillean islands of Guadeloupe, Dominica, and Martinique are among the wettest regions in the entire Western Hemisphere, receiving as much as 8 meters of rain in a year.

Streams are plentiful in the more mountainous of the West Indies. This one is near Marigot, north-eastern Dominica, Lesser Antilles.

The Luquillo Mountains, seen here from the coast, are located in eastern Puerto Rico.

They collect a lot of humidity from the Atlantic Ocean and are the wettest region in that Greater Antillean island.

Similar patterns of rainfall occur everywhere in the West Indies.

Stream. Near Grenvile, eastern Grenada, Lesser Antilles.

La Mina Creek. El Yunque National Forest, north-eastern Puerto Rico.

Small mountain streams like this one may become raging torrents during downpours of rain. Along their margins, the rain forest closes into a green wall on each side.

The first Europeans who reached the American tropics usually explored along navigable waterways, and thus thought at first that rain forests were impassable jungles.

The headwaters of the Espíritu Santo River cut a gorge

through the El Yunque National Forest, north-eastern Puerto Rico.

Ecosystems

    The Antilles do not have a complex freshwater fish fauna. There are a few dozen endemic fishes in Cuba, Hispaniola, Jamaica, and some of the Lesser Antilles. Among these species there are several blind troglodytes in Cuba. Aside from fish, several groups of organisms have evolved a number of endemic species in freshwater habitats. There are aquatic anoles in Cuba and Hispaniola, troglodyte amphipods and shrimp in Puerto Rico and Mona Island, freshwater clams in the Greater Antilles, and terrestrial rain frogs that have reverted to a life in water, at least partially, in all the Greater Antilles and in some of the Lesser.

    The lowlands of larger islands frequently have freshwater, brackish, and saline wetlands of diverse sizes which, like mountains and xeric regions, may have high concentrations of local endemics (organisms that live only in a given area: island, lake, mountain range, etc.). The Zapata Swamp of Cuba and the Enriquillo Lake of Hispaniola are the best examples of these ecosystems in the West Indies. A few natural lakes and ponds are found in the Antillean highlands, as well.

The "Dead Sea of the Caribbean": Lake Enriquillo. South-western Dominican Republic, Hispaniola.
Although today it is found many kilometers away from the nearest ocean, this hypersaline lake is a
remnant of a shallow sea that once separated the northern and southern paleoislands of Hispaniola
In truth being neither as salty nor as "dead" as its Israeli homologue, this unique West Indian
lake and its surroundings have a rich fauna and flora with a high degree of local endemism, including

properly marine fish and mollusks.

The Bahoruco Mountains seen from Lake Enriquillo.

A storm hovers near Lake Enriquillo, as wind churns its usually placid waters.

The Neiba Range is seen beyond it.

Cabritos Island, in the middle of Lake Enriquillo, is a xeric ecosystem filled with cacti and thorn brush.

A southward view of Lake Enriquillo at dusk, from the Neiba Mountain Range, in the northern Hispaniolan paleoisland.

In the distance, the foothills of the Bahoruco Mountains, in the southern paleoisland. The lake and the surrounding

lands are a jewel of biodiversity among the Caribbean islands. It is now a national park, enjoying protection of its biological treasures.

Part of Cabritos Island can be seen in the middle of the lake, in the upper-right quadrant of the photograph.

Grand Etang, central Grenada, Lesser Antilles.

This lake is located in the crater of an extinct volcano.

    Worldwide, forests that grow on a base of limestone are called "karstic" forests. Among them, those growing in tropical humid areas may resemble rain forests in appearance. They are generally drier, though, since the porous limestone allows for much of the rain water to percolate beyond the reach of the trees' roots. However, in the Antilles, the absolute biodiversity in these forests is sometimes higher than that of the rain forests of the same islands. In fact, karstic regions in the Caribbean are centers of local endemism, and many West Indian animals (Puerto Rican giant anoles, Jamaican fruit bats, greater Puerto Rican boas, Hispaniolan parrots, Cuban hutias, and others) make them their favorite haunts.

    On the other hand, there are xeric karstic forests, also. Because of the aforementioned porous structure of limestone, xeric forests and grasslands that grow on a limestone base in arid regions tend to be the driest among the dry. In some areas, forest gives way altogether to grassland.

    Some of the Lesser Antilles have karstic areas, albeit these are of lesser extension than their counterparts in the Greater Antilles and the Bahamas.

    In some regions of the Greater Antilles, the substrate is formed by a rock called "serpentinite". Its parent mineral, "serpentine" is usually bluish-green in color, soft, and highly porous, and its name derives from the wavy, snake-like color patterns noticeable at close range. It is a metamorphic igneous rock composed of magnesium silicates, together with cobalt, chromium, manganese, and nickel. It erodes into soils that are highly alkaline and very poor in nutrients. Moreover, its chemical composition is toxic to many plants. The combination of lack of nutrients, toxicity and dry soils makes life difficult for many plants, and so the vegetative associations growing in these areas have relatively few species. This flora has a high proportion of slow-growing species adapted to the toxic and arid conditions, and many of them are endemic to these areas. Serpentine soils in humid regions are responsible for a paradoxical situation: that of "dry rain forests". The apparent oxymoron is not such, in reality, since indeed it might rain a lot there, but the water percolates very quickly, so the wet, even swampy, conditions of typical rain forest soils are not found in these regions. An example of this type of vegetation is found in the Maricao and Susua state forests, on the western end of the central highlands of Puerto Rico, and in several regions in Cuba.

Serpentine is a blue-green (sometimes reddish or black) mineral superficially similar to marble and limestone. It forms the main substrate in some areas of the Greater Antilles.

Forests growing on it have a high level of endemism that compensates for their biotic poverty.

Maricao State Forest, western Puerto Rico.

This forest growing on a serpentine base represents a transition between xeric and montane rain forest.

Susua State Forest, south-western Puerto Rico.

View of the higher reaches of a montane tropical rain forest growing on serpentine soils. Maricao State Forest, western Puerto Rico.

Compare the almost scrubby vegetation of this region with those of more typical highland tropical rain forests shown elsewhere on this page.

Many of the plants growing on serpentine are adapted to dry conditions even when living in otherwise humid areas.

They often take the form of thorny, sclerophyllous trees and bushes, their leaves covered in wax to prevent water loss,

as is often the case with plants from xeric regions. Some trees have small leaves and flat crowns, resembling those of trees growing in savannas.

Maricao State Forest, western Puerto Rico.

    Although soil types greatly determines what sort of vegetation will grow in a given area, there is one factor that weighs even more on this matter: water.

    In the Antilles, where rainfall averages between 100 to 250 centimeters a year the lowlands of the Antilles are covered in tropical humid forests. These same associations are called "montane" humid forests if rainfall is still relatively low but the forests cover the slopes of mountain ranges to an altitude of about 500 meters.

Lowland humid forest. Near Creque Dam, western Saint Croix, United States Virgin Islands.