the big topjourney into amazonia

the big topThe canopy shelters the Earth's richest and most diverse ecosystem. Estimates of its insects alone have recently jumped from one and a half to 30 million different types. But its very richness is the greatest paradox of Amazonia. Jungle giants, among the tallest trees on Earth, spring from remarkably poor soil. 99% of the nutrients never reach more than two inches into the barren acidic earth. Nothing should grow in the Amazon at all. Yet all around, life is abundant. From the centuries- long rise and fall of one of these mighty trees, to the annual ebb and flow of the floodwaters, thousands of cycles of regeneration breathe life into the rainforest itself. Nine tenths of the energy of this gigantic system is jealously guarded in the leaves and tissues of the trees themselves. The forest floor is a living sponge, which prevents minerals and nutrients from being washed away and lost. This is the tightest, most efficient recycling operation in nature. It is also a fragile one. If the thin layer of humus is removed, the system withers away, and with it all the life it supports.

High above the forest floor is Amazonia's treetop world. Nine times the size of Texas, the canopy -- less studied than the ocean floor -- is home to millions of undiscovered species. In fact, until recently the canopy defied even the most intrepid biologists. Scientists now believe the canopy may house half the world's species. Amazonia's staggering cast list includes 500 mammals, 175 different lizards, 300 other reptile species, tree climbers of every kind, and fully a third of the world's birds. With so many creatures drawn to the attractions of this high rise world, competition for survival at the top is intense.

This competition and millions of years of evolution help explain why there are so many highly adapted species in the rainforest canopy. The most intricate relationships in the rainforest are between animals and trees. In this competitive market, leaves are the most common currency. In each leaf is sunlight trapped by the forest and turned into energy-filled matter. This self-sufficient system supports not only the trees themselves but also the countless herbivores of the canopy.

Featured Wildlife: The Big Top

Harpy eagle (Harpia harpyja)
Though not the largest raptor, the harpy eagle is far and away the most powerful. Females, renowned for their seven-foot wingspan, are significantly larger than their male counterparts. In fact, the female eagle is strong enough to carry away a full-grown monkey. The harpy eagle prefers to eat mammal prey, such as monkeys, kinkajous and sloths, though if times are tough, it will settle for reptiles or smaller birds.

Life for harpy offspring is difficult for both the chicks and the parents. Chicks take two months to hatch, and from that point forward, the parents devote themselves to raising the new birds. The effort is so taxing that the parent birds will wait two to three years to nest again.

Three-toed sloth (Bradypus tridactylus)
It's no wonder that being a sloth is associated with lethargy. The three-toed sloth is the least active mammals on earth, spending nearly 80 percent of its life resting. When it moves, the sloth moves at molasses-like speeds of approximately a tenth of a mile per hour. Evolution has optimized the sloth for immobility; it has roughly half the muscles of other comparably sized animals.

Keeping as still as it does may have something to do with the sloth's relationship to algae. The sloth is the only wild animal that has plants living on it. Each hair on the sloth's body has microscopic grooves where green algae reside. The algae receive shelter from the sloth's hair; in return, the algae help camouflage the sloth from predators like the harpy eagle.

Like everything else it does, the sloth takes an interminably long time to digest its diet of leaves -- usually the worst leaves in the forest, thanks to the sloth's non-competitive nature. Eating as it does, it can take the sloth 150 hours to digest its food. Sometimes, leaves reside in the sloth's intestine for nearly a month.

Howler monkey (Alouatta caraya)
The howler monkey, the most widespread primate in the New World, gives the sloth a run for the money when it comes to sluggishness. A good portion of a howler's diet is comprised of leaves (though they prefer figs), which means that the monkey spends a good deal of its daytime energy digesting and resting. With such low metabolism, howler monkeys have to move into the sunlight to warm up after cold nights.

One stirring thing the howler monkey can do is howl. When the first explorers came to Amazonia, they fled at the sound of roaring howlers, believing that some terrible creature was readying to attack. Howler monkeys are able to produce these blood-curdling sounds courtesy of an egg-shaped bone in their windpipes. This bone helps amplify the sound of their howling, so much so that a male howler can be heard howling for two miles or more.

Leaf-cutter ant (Atta sp.)
The many species of leaf-cutter ants that live in Amazonia are responsible for harvesting nearly a sixth of the area's leaves. They consume far more vegetation than any other equally spread group of animals. In the course of bearing a leaf fragment from the harvested tree to their colony, female worker ants undergo an arduous journey. The human equivalent of the trip would be running four-minute miles for nearly 30 miles, all the while carrying a weight of 500 pounds. Leaf fragments are incorporated into the ants' vast underground colonies, which can be as large two household garages.

After millions of years of evolution, leaf-cutter ants are an essential part of the Amazonian ecosystem. They play a critical role as landscapers of the jungle, pruning vegetation, stimulating new plant growth, breaking down vegetation, and renewing the soil.

Macaw (Ara sp.)
It's no secret that the first visitors to Amazonia were struck by the beauty of the area's vast parrot population. The earliest drawn maps of the Amazon actually refer to it as terra papagallum, "The Land of Parrots." In the land of parrots, the largest and to some, the most beautiful, is the macaw.

There are many different types of macaw; the largest is the red and green variety. Because they are such choosy eaters, macaws are found throughout Amazonia. In fact, they will travel hundreds of miles to reach their preferred source of food. More often than not, if they can be found, macaws hone in on patches of burriti trees. For a mating pair of macaws, who stay together for life, a burriti tree is a welcome find. Burriti trees can provide a macaw with everything it will ever need: food, bed and a secure nursery for breeding.

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Journey into Amazonia
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