The Amazon Rainforest is the largest rainforest in the world. This extraordinary tropical jungle is roughly the same size as 48 states in the U. S.
The Amazon surrounds the Amazon River and its many tributaries. The Amazon River is the largest river in the world by volume discharged. It stretches an astounding 4,225 miles—from the peaks of the Peruvian Andes to the beautiful beaches of Brazil.
Scientists estimate there are 390 billion trees in the Amazon Rainforest, including over 16,000 species. If we include shrubs, climbing plants, algae, and fungi, the number of species climbs well over 40,000, but there are many more species waiting to be discovered. Plants, algae and fungi represent just a fraction of the Amazon’s ecological diversity.
The Amazon supports at least 427 mammal species, 3,000 species of freshwater fish, over 1,300 species of birds, 378 types of reptiles, and 400 species of amphibians. Notice how we didn’t mention any invertebrates, like insects and arachnids? That’s because the Amazon’s gargantuan population of invertebrate species climbs well into the millions.
And that only includes the species we’ve identified so far! But how does this gigantic ecosystem support so many diverse organisms? Scientists conceptualize the Amazon as four ecological layers: the forest floor, the understory, the canopy and the overstory.
Each layer plays an important role in the health and survival of the rainforest. The forest floor is where the rainforest finds its humble beginnings. The roots of towering trees grow in thick, low-nutrient soil laid over a layer of volcanic rock.
Without deep, rich soil, the forest floor’s tropical vegetation depends on decomposers, like bacteria, fungi and insects. These essential organisms pull nutrients from dead organic material, like leaves, wood, and animal carcasses. Vital for nutrient cycling, vibrant mushrooms, like the scarlet cup and the veiled lady, adorn the forest floor.
Some of these fungi are bioluminescent. When the sun sets over the Amazon, these radiant mushrooms illuminate the forest floor like magical nightlights. Very little sunlight penetrates the upper layers of the rainforest, so the forest floor remains dark and damp year-round.
Low levels of light make life challenging for plant species on the forest floor, but this layer is ideal for terrestrial animals. On the forest floor, you’ll discover spectacular insects like the Assassin bug, which impales its prey with a long, sharp proboscis. Other extraordinary insects hide in plain sight, like leaf-mimic Katydids, which disguise their tall, green bodies as rainforest vegetation.
The Amazon Rainforest is home to many of the world’s largest insects and arachnids. The Titan Beetle, for example, can grow up to 6. 6 inches long—that’s about the size of an adult human hand.
With such an astonishing population of invertebrates, there are predators a-plenty. Reptiles, like iguanas, and mammals, like the Giant Anteater, feed on huge colonies of ants and termites on the forest floor. Hanging no more than 12 feet above the forest floor, the second layer of the Amazon Rainforest is the understory.
The understory is populated by small trees, shrubs, and parasitic climbing plants. Like the forest floor, the understory is permanently shaded by a dense canopy. There are only a few species of flowering plants in the understory.
These plants attract pollinators with large, brightly colored blooms. Though it lacks direct sunlight, the understory produces a variety of edible fruits, including mangos, lemons, and cacao pods, which are used to make chocolate. The understory also houses an abundance of incredible animals.
Giant Waxy Tree Frogs live and feed on the understory’s low-hanging branches. Colonies of Vampire Bats hide in the sun-starved corners of the forest in well-structured family groups. But one of the understory’s most spectacular residents lurks in the undergrowth.
The Jaguar is the largest cat species in the Americas and an apex predator in the Amazon. Jaguars are confident swimmers with powerful jaws. Camouflaged amongst rainforest vegetation, these big cats hunt larger prey like deer, monkeys, and tortoises.
Rising above the understory, the rainforest canopy is the thickest layer of vegetation in the Amazon. This labyrinth of leaves and branches shields the understory and the forest floor. It keeps the lower layers damp and humid, while protecting them from dry winds and harsh sunlight.
To humans, this is the most inaccessible layer of rainforest. Scientists expect to discover the most species in the rainforest canopy, but exploring the canopy is a challenge all its own. The canopy receives ample sunlight, so delicate, flowering plants grow safely inside.
The canopy’s flora sustains a wide variety of animal species with their flowers and fruits. Beyond reptiles and thousands of insect species, who could forget the canopy’s most rambunctious population? Monkeys thrive in this complex network of vegetation, where they hide from apex predators.
Spider monkeys, Howler monkeys, Capuchins, Tamarins, and many more enjoy the canopy’s fruits, nuts and seeds. The canopy’s most impressive populations wear coats of colorful feathers. A majority of the Amazon’s birds live in the canopy, including some of the world’s rarest species.
The Long-billed Toucan, the Ragged Crested Hoatzin, and a variety of macaws fill the Amazon’s canopy with music and color. The emergent layer, also known as the overstory, is the fourth and final layer of the Amazon Rainforest. Trees in the overstory grow up to 200 feet tall.
Their massive trunks penetrate the canopy into the open air, where their branches spread wide, like umbrellas hanging over the forest below. The overstory is bright and dry, housing many large avian predators. Birds of prey, like eagles, owls and hawks, nest in the tallest trees, where they prey on animals in the canopy, like macaws and monkeys.
Scientists divide the Amazon into ecological layers, but this vast habitat functions as one cohesive system. Each species has evolved to fill a specific niche, from the darkest corners of the forest floor to the tallest treetops, 200 feet above the ground. It has taken millions of years for this ecological tapestry to grow and develop, but the Amazon is threatened now more than ever before.
Twenty percent of the Amazon Rainforest has already been destroyed, and deforestation rates are at a 12-year high. At the rate we’re going, the world’s greatest terrestrial ecosystem may collapse… and disappear completely. If the Amazon disappears, we will see increasing deficits in local rainfall.
That means drier air, savannah-like conditions, and frequent shortages of water. By destroying millions of trees, an excess of carbon will also accelerate global climate change, eradicating plant and animal species around the world. The Amazon Rainforest protects its millions of inhabitants, but it also preserves the health and balance of our global ecosystem.
To the untrained eye, the Amazon is a sprawling mess of trees, vines, and strange creatures. But, if you look inside its tangled canopy, you’ll discover a life-giving ecosystem unlike any in the world.
