RAINFOREST ANIMALS

Bennett's Tree-kangaroo mother & baby

Many people are disappointed when they visit a rainforest. Few see big animals. Mostly what they see is a lot of foliage way up in the air and ants and other insects on the ground. If they are lucky they catch glimpses of monkeys and tropical birds like macaws, parrots, toucans or hornbills among the leaves and shadows.

Most rainforest animals are small (the vast majority are insects) and live high in trees, where you can't see them. Don’t expect to see lions which are depicted in some cartoons and Hollywood movies as living in the rainforest because they don't actually live there. When there are large animals in the rainforest, they, like snakes, are shy and sense you before you see them, and usually hide or keep their distance from humans.

In the rainforest there are day creatures and night creatures. At dawn and dusk the rainforest is very quiet as both the night and day insects are at rest. But this also often the best time to view animals.

Large animals in the tropical rainforest browse on the limited amount of leaves in the understory and the rich vegetation close to riverbanks.

Complexity of Rainforest Creatures

It is also amazing how rainforest plants and animals are continually adapting to their environment. Plants develop poisonous alkaloids to protect them against insects; insects develop digestive chemistry to overcome these poisons; and aboriginals use the alkaloids these plants as well lethal frogs to tip the blowgun darts and spears.∩

Many species are confined to small areas or niches. The have specialized ecological needs and are easily affected by habitat change. Some flowers can only be fertilized one bee or bat and if they are lost the flower is also lost.

At night the tropical rainforest is alive with a variety sounds: howls, screams, clicks, whirs, coughs, barks, trills. Scientist have a great difficulty determining what kind of creatures make these sounds. Many of the sounds are territory claims where visual cues can not be seen and laying sent markers is too cumbersome.

Dramas are constantly taking place in the rainforest on a miniature scale. Thorn-shaped treehoppers are protected from spiders and wasps by ants who feast on the treehopper's sugar laced excrement; flies mating in mid air are gobbled up by giant butterflies and moths; arboreal dragonflies fly across the leafy crowns of trees the same way they skim across ponds; polychromatic frogs and lizards are swallowed whole by snakes; and ants with bear trap jaws rotate their head vertically to snag insects.▸

Camouflage and Deception among Rainforest Animals

Keel-billed toucan

Camouflage and deception are important for the survival of many species in the rainforest and the tropics where there is a lot of animal life and nearly everything is food for something else. Among the creatures that excel at the art of deception are leaf-litter toads, that disappear into the forest floor in Panama; the flag-footed bug, which attempts to divert a hunter’s attention with red flags on the insect’s legs that keep hunters away from essential organs on its main body; and caterpillars that rear up like striking snakes when threatened and display a par of spots that look like scary snake eyes. Walking leafs from Malaysia can be as long as 10 centimeters. They are little changed from ancestors found in 47-million -year-old fossils in Germany. [Source: Natalie Angier, National Geographic, August 2009]

Describing the creatures on Barro Colorado Island in Panama, Natalie Angier wrote in National Geographic, “Parts of the tree seem to be unfixing themselves and wandering at will. A four-inch twig buzzes overheard and thuds into a nearby branch. A lime green leaf stares through a pile of brown leaves, finds nothing of interest, and crawls towards another pile. The “twig” is a stick insect, a magnificent specimens of the Plasmatodea clan, its outer sheath persuasive rendering of striated bark, its tubular body and head punctuated by fake axillary buds and leaf scars — the little knobs and notches that make a twig look twiggy...During the day these insects move little and are nearly impossible to distinguish from the sylvan backdrop they imitate, and that, of course, is the point: to remain invisible to sharp-eyed predators that use vision to hunt. Come nightfall, however, stick and leaf katydids shake off their vegetable torpor to some feeding of their own — on leaves and forest-floor detritus.

In many cases — perhaps most cases — camouflage and deception allow a creature to avoid predators or elude detection by prey or both. Angier wrote “I found a mantid that looked like a few sprigs of radicchio, the perfect cloaking device for a stealth hunter or a leaf-eating insect that itself is much coveted by insectivorous reptiles and birds.” Katydids often employ mimicry because they are fleshy, protein-rich and toxin free and as a result are frequently fed on by monkeys, birds, lizards, frogs and snakes. The same is true with nonpoisonous butterflies that have developed markings similar to those of poisonous species.

Visual mimicry is the most well-documented and obvious form of mimicry but auditory mimicry also exists. One species of tiger moth that bats like to feed on, for example, produces ultrasonic clicks of moths that bats detest. The great racket-tailed drongo of Sri Lanka mimics she calls of other birds to generate mixed-species flocks in which drongos can more safely and efficiently forage. In New York, small green frogs sometimes croak like large green frogs to keep intruders away from their territory.

There is also olfactory mimicry. Some species of orchids produce smells like dead meat to attract flies that serve as pollinators. Bolas spiders attract male moths by producing imitations of the female moth’s scent. There is even tactile mimicry. One species of parasitic fungus makes its home in termite nest by adopting the shape and texture of eggs of essentially blind termites.

Scientists are particularly interested in mimicry that seems incomplete or imperfect in some way to gain understanding into different means of deception are created and what happens when they outlived its usefulness and the creature is evolving away from it. Evidence shows that wingless stick insects have evolved wings and got ride of at least four times in their history. This finding shocked scientists.

Rainforest Mammals and Birds

About 70 percent of the 4,000 known mammal species are found in rainforests. About 90 percent of all primates are found in the tropical forests.

The most abundant mammals in the tropical rainforest are mice and rats. The two note mating whistles of some species of rat are often mistaken for the calls of insects and birds. Most of the mice are nocturnal animals whose vision is enhanced by huge dilating pupils. Wooly opossums are the most abundant mammal in the canopy of undisturbed forest in the Amazon basin.

Of the 9,000 known bird species, more than half are found in rainforests, with about a fifth of them in the Amazon. There are lots of birds and bird species in the rainforest because there lots and lots of different kinds of insects, fruits, seeds, flower nectar for them to feed on Birds are important for dispersing seeds. Many birds fly through the trees. Those that fly above the canopy are vulnerable to attacks from eagles.

In the understory of the tropical rainforest, mixed-species flocks of 12 to 13 birds sometimes forage together. In the canopy a similar pattern exists with completely different species. The different species in the flocks often have the same 28 to 33 acre territories, with individual birds staying in the same territory for years.

Bats in the Rainforest

leaf-nosed bats

According to World Rainforests: The most abundant mammals in the rainforest are not large ground-dwelling creatures, but bats. The tropics have the greatest variety of bats, and accordingly, the most diverse mammalian group of the tropical rainforest is bats, making up over 50 percent of mammal species. Bats range in size from the giant flying foxes, with wingspans of six feet (1.8 m), to the tiny bumblebee bat of Thailand, the world's smallest mammal, weighing less than an American penny. Equally diverse are the feeding habits of tropical bats, which include fruit, nectar, blood, and carnivorous feeders; and the places bats choose for shelter.

Although most bats of the world are insectivores, rainforests have a high percentage of fruit eaters. While insectivorous and other carnivorous bats rely on echolocation to find their prey, fruit-eating bats depend mostly on sight and a sophisticated sense of smell. True fruit-eating bats, the flying foxes of Madagascar, India, Sri Lanka, Southeast Asia, New Guinea, and Australia, did not reach the New World, so their niche was filled by spear-nosed fruit bats which evolved from insect-eating bats. Today, countless canopy plant species depend on bats for pollination or seed dispersal, making bats the best mammalian dispersal agents.

Nectar-feeding bats are important pollinators of tropical rainforest plants. Like fruit-eating bats, nectar-feeding bats rely on sight to locate their primary source of food: flower nectar. Thus flowers targeted by these nocturnal bats are night-blooming and are easily seen in relative darkness with large, white petals. Nectar-feeding bats are equipped with a long, thin tongue, like that of a hummingbird, to reach nectar deep inside the flower.

Besides the best known insectivorous bats—each individual may eat over 3,000 insects a night—several bat species feed on vertebrate animals. One of the most notable bat groups are the fishing bats which have echolocation so sophisticated that they can detect minnows swimming at the water surface. Other bats feed on frogs and are able to distinguish poisonous species from edible species by listening to their calls. These bats associate the bad experience of eating one of these toxic frogs with their call.

Golden Toad — First Species Made Extinct by Climate Change?

The golden toad — the size of a child’s thumb — that lived the Monteverde cloud forest in Costa Rica was a poster child for rainforest preservation after it was featured in National Geographic magazine and then climate change activism after it went extinct in 1990 and was in 2022. highlighted in a UN report this year. Rob Waugh wrote in Yahoo News UK: Researchers warn that more and more species are threatened by climate change. Around one million species already face extinction, many within decades, according to the recent Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) assessment report. [Source: Rob Waugh, Yahoo News UK, April 13, 2022]

J Alan Pounds, an ecologist at the Monteverde Cloud Forest Preserve in Costa Rica, told AFP: "The soils are very dark and so golden toads would stand out like animal figurines. It was quite a spectacle. It was pretty clear about 99 percent of the population declined within a single year. We haven't completely given up. But with each passing year, it looks less likely that they're going to reappear."

The golden toad was singled out in the UN’s Intergovernmental Panel on Climate Change (IPCC) report this year. Even if warming is capped at 1.5C above pre-industrial levels, the IPC says nearly one in 10 of all species face an extinction threat. The golden toad only lived in one area in Monteverde’s highland forest — so global warming had a huge impact after unusually warm and dry periods.

Pounds and his colleagues linked the decline in frog numbers to chytridiomycosis infection, triggered by climate change. Pounds said: "We hypothesised that climate change and resultant extreme events were somehow loading the dice for these kinds of outbreaks.” At 1.5C warming, scientists expect 3-14 percent of the world's species on land could vanish, this year’s IPCC report warned.

Rainforest Insects and Worms

golden toad

In a single square mile of tropical rainforest there are 50,000 different insect species (more than all the world's mammal, bird, reptile and amphibian species combined). They include bumblebees the size of small birds, six-inch praying mantises, nine-inch walking sticks, grasshoppers, leafhoppers, dragonflies, beetles, ants, mites, bees, katydids, caterpillars, and weevils. A single site can have more species of katydids and beetles than are found in all of Europe.

Many species of insects have their unique species of mites and parasites that live on them. Most species of rainforest mites, which may be the most abundant creatures in the canopy and the most important in breaking down nutrients, have yet to cataloged are labeled. Most mite species that have been described have only been discovered in the last few years. Some insects specialists have discovered thousands of new species.

Among the most bizarre insects found in the rainforest are poisonous caterpillars that look like pieces of cotton candy; giant weevils that carry miniature gardens of lichens and mosses on their backs; and ants that groom each other while spreading antibiotic substances. Some species of grasshopper pretend they are wasps to keep predators away. Some kinds of damsel flies raid spider webs to steal the immobilized insects and pop the spiders "like a grape." Treehoppers are well-protected with hard shells and spikes on their backs. ▸

The rainforest is full of wasps. Some species build their nests from wood pulp, and if it rains they lap up water drops to keep the nest from disintegrating. Katydids sometimes gather around wasp nests as protection from predators and the wasps themselves smear a black secretion around the nest to repel ants who feed on wasp larvae.

Velvet worms found in the rainforest have some unusual mating habits. Among some species, the male deposits sperm on the top of the female’s head. The males of other species puts sperm on their heads and delivers it to the genital area of the females at the rear of their bodies. In some species females lay eggs outside their bodies; others lay them inside their bodies; others still give birth to live young.

Insects, Ants, Leeches, See Creatures of the World

Treehoppers

Douglas Main wrote in National Geographic:“If there were a competition for the world’s weirdest insect, treehoppers would have a clear shot at first place. See one for the first time and you’re sure to wonder: What are those strange protrusions sprouting from its body? Many treehoppers flaunt outlandish outcroppings, such as the helicopter-like orbs of Bocydium sp. Others play it coy, mimicking thorns, leaves, or insect droppings. Still others impersonate ants or wasps. Forty-plus named species, as well as another 700 or so awaiting scientific description, resemble drops of rainwater. Those singular shapes, insect anatomists explain, stem from the treehopper’s specially modified pronotum — a section of the thorax that in other insects resembles a small, shield-like plate. But treehoppers are the creative kids in their class, with their pronota arching into grotesque spires or globes, veritable billboards of their individuality. [Source: Douglas Main, National Geographic, March 2019]

“As their common name suggests, these tiny insects — none are longer than a dime is wide — live on trees and plants worldwide, with nearly half the 3,200 or so described species inhabiting the New World tropics. One leaf in the Ecuadorian rainforest where this story was photographed could easily harbor more treehopper species than found in all of Europe.

“Treehoppers are members of a huge and varied order of insects known as the Hemiptera, which include leafhoppers and cicadas. Like others of their kind, they’re equipped with mouthparts for piercing plant stems and slurping the juices inside. A bit like mosquitoes, they have two interlocking, needlelike feeding tubes, one for siphoning fluids, the other for secreting saliva that prevents the juices from coagulating.

Treehopper Characteristics and Behavior

oak treehopper

Douglas Main wrote in National Geographic:“Because they’re often content to feast on one plant’s bounty their entire life, most treehoppers pose little threat to economically important crops (though they may spread at least one botanical disease). Partly for this reason, treehoppers haven’t been studied as extensively as their close relatives. This lack of scientific attention has left significant gaps in our knowledge of these bugs, including the purpose of their mystifying body modifications. [Source: Douglas Main, National Geographic, March 2019]

“It’s a good bet that those pronounced pronota help protect treehoppers from predators. Spines and barbs warn that they might be tough to swallow, and bright colors advertise toxins within. Mimicry — the art of appearing to be something else — also plays a defensive role. The strange globes crowning Bocydium’s body resemble globs of Cordyceps, an insect-killing fungus common in rainforests.

“While it’s tantalizing to imagine what information treehoppers may glean with these receptors, their main mode of communication involves plant-borne vibrations. In contrast to their cicada cousins, which communicate by rubbing body parts together to produce shrill songs, treehoppers shake and jerk their bodies to send signals through plants, says Rex Cocroft, a researcher at the University of Missouri. Cocroft and other researchers record these vibrations with microphone-like devices that reveal a chorus of calls, clicks, chirps, and songs — none of which are audible to the human ear.

“This ability to communicate with each other helps treehoppers defend their young. Unlike most insect mothers, which desert their eggs soon after laying them, many treehopper mothers remain present and vigilant, guarding their offspring until the nymphs grow up and fly away. When predators such as stinkbugs approach, the nearest nymph sounds the alarm by swinging its body and producing a vibrational “chirp.” Siblings pick up the vibe and join in, amplifying the signal. Springing into action, the mother confronts the invader, furiously buzzing her wings or punching with her club-shaped back legs.

“Though the pronota are large, they’re also hollow and lightweight, allowing the insects to fly with surprising ease. Intriguingly, their pronota are wired with nerves and hairlike structures known as setae that receive unknown stimuli and may help the bugs sense their environment, says Stuart McKamey, a researcher with the U.S. Department of Agriculture’s Systematic Entomology Laboratory.

Types of Treehoppers

Treehoppers take on many disguises, all with the same purpose: to look like anything but a tasty insect. Stegaspis fronditia resembles a thorny leaf. Those of the genus Heteronotus mimic ants and/or wasps. Membracis nymphs have spikes to dissuade predators. Chelyoidea sp. mimics the texture and color of turtle ants. A treehopper of the Cladonota genus looks like a bird dropping. Anchistrotus sp. can lose its “helmet” and still survive. Stylocentrus rubrinigris seems to mimic insect-killing fungi. [Source: Douglas Main, National Geographic, March 2019]

The devil treehopper, Hemikyptha marginata, is the world’s largest known treehopper species. A prickly Cladonota biclavata patrols trees near Ecuador’s Napo River. Found from Mexico to Argentina, some treehoppers in this genus have among the largest pronota (their modified thoraxes). “It’s pretty amazing that these things can even hop or fly with this big thing

Known for their devoted parental care, treehopper mothers of the species Alchisme tridentata watch over their progeny until the young hoppers are old enough to fly away. The nymphs have barbs and bright red and yellow accents, probably warning that they’re unpalatable. A spiky mouthful, Alchisme grossa has thornlike barbs that may dissuade would-be predators. This perturbed bug perched on a red leaf after flying away from photographer Javier Aznar González de Rueda. But members of this species are more commonly found on folia.

Douglas Main wrote in National Geographic: Sometimes treehoppers get help from ants and other insects that provide protection in exchange for honeydew, a sweet liquid treehoppers secrete as a product of constantly drawing plant sap.“Collecting treehoppers that have ant allies can be painful: “You’ll get dozens of stings on your hands,” says Chris Dietrich, curator of insects at the Illinois Natural History Survey. But the astonishing variety of these bizarre bugs makes for endless surprises. “When you work with insects,” McKamey says, “it’s like Christmas every day.”

Image Source: Mongabay mongabay.com

Text Sources: “The Private Life of Plants: A Natural History of Plant Behavior” by David Attenborough (Princeton University Press, 1997); National Geographic articles. Also the New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated November 2024