49 Fun Facts About Rainforests

After the Amazon, the world's second-largest tropical rainforest lies in which river basin?

The Congo Basin holds the second-largest tropical rainforest, about 2 million km² across six countries, roughly a third the extent of the Amazon, with some of the largest undisturbed stands on the planet.

The Amazon rainforest lies on which continent?

The Amazon rainforest lies entirely in South America, spread across Brazil, Peru, Colombia and several neighbouring countries.

What is the uppermost stratum of a rainforest, where the tallest trees rise above the rest, called?

The emergent layer consists of scattered giants such as kapok trees that rise above the continuous canopy, exposed to strong winds, full sun and low humidity, with small leaves and buttressed trunks.

Many rainforest plants have leaves with a 'drip tip.' What is the primary purpose of this adaptation?

Drip tips are an adaptation in rainforest plants that allow water to run off the leaves quickly, preventing the growth of fungi and algae that could block sunlight and hinder photosynthesis.

Which big cat is the apex predator of the Amazon rainforest?

The jaguar is the biggest cat in the Americas and the third largest in the world, ranging from the southwestern United States to northern Argentina.

What is considered the leading cause of deforestation in tropical rainforests globally?

Agricultural expansion, above all cattle ranching and crops like soy and palm oil, is the primary driver of rainforest loss worldwide; logging adds to the fragmentation.

What is the typical average annual rainfall in a tropical rainforest?

Tropical rainforests are defined by their high precipitation, typically receiving between 1,750 mm and 3,000 mm of rain annually, though some areas can receive much more.

Which country has the largest share of the Amazon rainforest within its borders?

Brazil is home to the largest portion of the Amazon rainforest, containing approximately 60% of its total area.

Despite their dense vegetation, what are most tropical rainforest soils like?

Rainforest soils are heavily leached and nutrient-poor: constant rain washes soluble nutrients away, so most minerals sit in the living plants and the thin litter layer on top.

The English word 'jungle' comes from a Sanskrit word meaning what?

Sanskrit jaṅgala meant 'rough and arid' land or dry scrub; the word reached English in the 18th century via Hindustani, and its meaning drifted to dense tropical tangle along the way.

Ecologists distinguish a jungle from a rainforest interior mainly by what?

Under a closed canopy so little light reaches the floor that a mature rainforest is fairly easy to walk through; the tangle grows where light gets in.

Before the 1970s, roughly what share of print references to tropical forests said 'jungle' rather than 'rainforest'?

A corpus study found 'jungle' in over 80% of print references before the 1970s; 'rainforest' only entered English dictionaries that decade, as these forests came to be seen as fragile rather than menacing.

Theobroma cacao, the source of chocolate, is native to the rainforests of which region?

Theobroma cacao originated in the upper Amazon basin, where wild populations show the greatest genetic diversity and use dates back some 5,300 years; West Africa only received the tree in the 19th century.

The Amazon rainforest spans the territory of how many nations?

Nine: Brazil, Peru, Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname and France via French Guiana; Peru holds the second-largest share after Brazil, at about 13%.

Roughly how many individual trees are estimated to grow in the Amazon rainforest?

A 2013 estimate put the Amazon at about 390 billion individual trees of some 16,000 species; the region also holds an estimated 2.5 million insect species.

Much of the phosphorus that fertilises the Amazon arrives as dust blown from where?

More than half of it comes from a single dry lakebed, the Bodélé depression in Chad, and NASA satellites track the plume across the Atlantic.

Who was the first European to travel the length of the Amazon River, in 1542?

Francisco de Orellana named the river after the warrior women of Greek myth following a fight with local tribes in 1542; his reports of large riverside cities were long dismissed as exaggeration.

The claim that the Amazon produces a fifth of the world's breathable air misuses a figure for what?

The figure refers to gross oxygen turnover: rainforests consume nearly all the oxygen they make through respiration and decomposition, so their net contribution to the atmosphere is close to zero.

By 2022, roughly what fraction of the Amazon rainforest had already been deforested?

A 2022 study put irreversible loss at about 20% of the original forest, with a further 6% highly degraded; the Trans-Amazonian highway of the 1970s opened much of it up.

The Daintree Rainforest, among the oldest rainforests on Earth, is in which country?

The Daintree lies in Queensland, Australia, about 105 km north of Cairns, and is one of the few places where rainforest runs straight down to coral-fringed beaches.

The Daintree takes its name from Richard Daintree, who was what?

Richard Daintree (1832–78) was a Queensland government geologist and pioneering field photographer; in 2021 the eastern Kuku Yalanji people won formal ownership of over 160,000 hectares, including the national park.

The tropical rainforest biome lies roughly between which two lines of latitude?

The tropical rainforest biome lies roughly between the Tropics of Cancer and Capricorn; temperate rainforests exist far outside that band, from Chile and the Pacific Northwest to the west coasts of Scotland and Ireland.

The Mbuti, Efe, Aka and Baka peoples are hunter-gatherers of the rainforests of which region?

All four live in the Congo Basin forests of Central Africa, the Mbuti and Efe in the DR Congo's Ituri, the Aka and Baka in Congo, Cameroon and Gabon; the Dayak and Penan are Borneo's forest peoples.

Which snake, the world's heaviest, hunts in Amazon rivers and swamps?

The green anaconda is the world's heaviest snake, with large females exceeding 5 metres and 100 kg; it ambushes capybara and caiman from Amazon rivers and swamps.

The grooved hair of a sloth's coat hosts what, giving the animal a greenish camouflage?

The same growth feeds sloth moths, some species of which live nowhere else; the sloth itself only climbs down about once a week to defecate.

Of more than 170 poison dart frog species, how many are documented as used to poison blowdarts?

All four belong to the genus Phyllobates; curare from plants was the more usual dart poison.

The golden poison frog carries enough toxin on average to kill roughly how many people?

An average golden poison frog carries about one milligram of batrachotoxin, enough to kill ten to twenty people; the toxin comes from a diet of ants, mites and termites, so captive-bred frogs are harmless.

The harpy eagle, the largest bird of prey in its range, hunts from which layer of the rainforest?

Harpy eagles nest in emergent trees such as kapoks and hunt sloths and monkeys in the upper canopy; logging has all but wiped them out of Central America outside pockets of Panama and Costa Rica.

Wild orangutans are native to which two islands?

Orangutans survive in the wild only on Borneo and Sumatra; a third species, the Tapanuli orangutan of Sumatra, was only described in 2017.

The okapi of the Congo rainforest, striped like a zebra, is most closely related to which animal?

The okapi is the giraffe's only living relative, the two making up the family Giraffidae; Europeans had heard rumours of an 'African unicorn' for years before it was formally described in 1901.

The capybara, native to every South American country except one, holds what record?

The capybara is the largest living rodent; Chile is the only South American country without them, and their groups can reach a hundred.

Leafcutter ants carry leaves back to their nests in order to do what?

The ants farm fungus: the chewed leaves feed a fungal garden that in turn feeds the colony, which can hold millions of ants under a mound more than 30 metres across.

The Sateré-Mawé people of Brazil use which rainforest insect, sewn into gloves, in initiation rites?

Bullet ant (Paraponera clavata) stings top the Schmidt pain index at level 4 and can burn for a full 24 hours; dozens of sedated ants are woven into each glove.

Rafflesia arnoldii of Sumatra and Borneo holds which botanical record?

Rafflesia arnoldii bears the largest individual flower, up to about a metre across; it is a parasite with no leaves or stem of its own and smells of rotting meat, hence the nickname corpse flower.

The buoyant, water-resistant fluff of the kapok tree was once widely used in what?

Kapok fibre filled life jackets and mattresses until synthetics replaced it after the Second World War; the tree is sacred in Maya mythology and is a national emblem of Guatemala, Puerto Rico and Equatorial Guinea.

Henry Wickham shipped 70,000 seeds of which Amazon plant to Kew in 1876, breaking Brazil's monopoly?

The seedlings raised at Kew seeded the plantations of Malaya and Ceylon, and the Amazon rubber boom collapsed within a generation.

Tarsiers of Southeast Asia cannot move their enormous eyes, so how does a tarsier look around?

Each eyeball is about 16 millimetres across, and the skull is built to balance the weight of the eyes.

As of 2019, roughly how many mountain gorillas remained in the wild?

They live in just two populations, the Virunga volcanoes and Uganda's Bwindi Impenetrable National Park.

The hoatzin, Guyana's national bird, is nicknamed the 'stinkbird' because of what?

Its chicks also hatch with claws on their wings, which they use to clamber back into the nest after dropping into the water to escape predators.

Which US president's 1913 Amazon expedition and book cemented the piranha's fearsome reputation?

Theodore Roosevelt's Through the Brazilian Wilderness (1914) described a piranha feeding frenzy that locals had staged with starved fish; piranhas are in fact omnivores that often eat plant matter.

The Amazon river dolphin is the largest river dolphin and is nicknamed for what?

Adult males are the pinkest; the species has unfused neck vertebrae that let it steer through flooded forest.

What share of natural medicines were discovered in tropical rainforests, the 'world's largest pharmacy'?

Over a quarter of natural medicines were found in rainforests, hence the 'world's largest pharmacy'; estimates put 40% to 75% of all living species there, many still undiscovered.

Roughly what percentage of the sunlight hitting a rainforest canopy reaches the understory?

About 5% of the light hitting the canopy gets through to the understory, and the floor gets only about 2%, which is why it stays relatively clear except near rivers, swamps and clearings.

By some estimates, the rainforest canopy layer is home to what share of all plant species?

By some estimates the canopy holds 50 percent of all plant species; its trees typically stand 30 to 45 metres tall, with epiphytes clinging to their trunks and branches.

Emergent trees towering over a rainforest canopy typically reach what height?

Emergents typically reach 45–55 metres, with a few species occasionally at 70 to 80 metres; they must withstand the heat and strong winds above the canopy.

The laterization process gives rainforest oxisols their bright red colour and sometimes produces deposits of which ore?

Laterization leaches silica and leaves iron and aluminium oxides, the reds of oxisols; where aluminium hydroxides concentrate, the residue is mined as bauxite, the ore of aluminium.

Tropical rainforests typically lie within how many degrees of latitude of the equator?

True tropical rainforests typically lie within 10 degrees of the equator, where mean monthly temperatures stay above 18 °C all year and there is usually no substantial dry season.

Dry rainforests, with their more open canopy, typically occur in what kind of location?

Dry rainforests grow in the rain shadow of mountains, as in parts of eastern Australia; their species often show adaptations such as deciduousness, small leathery leaves, thorns and prickles.

Alongside a closed canopy and epiphytes, which of these defines a rainforest?

Rainforests are defined by a closed canopy, moisture-dependent vegetation, epiphytes and lianas, and the absence of wildfire; high humidity and a moist layer of leaf litter complete the picture.