Understanding the Forest Structure
Every rainforest is divided into four layers, which different forest dwellers find to be suitable habitats. All species are equipped with survival and adaptation skills and part of these skills includes choosing the right forest layer to inhabit.
The Forest Floor – This is the bottom layer, which is zero feet above the ground. In a temperate rainforest the ground, the rocks and the tree trunks are covered with thick moss, grasses, lichens, algae and small plants.
During fall, this becomes covered with a thick litter of dead fir needles, leaves and twigs and sometimes snags of fallen trees. In contrast, a tropical dry rainforest will have very little or no ground vegetation.
The Understory – This refers to the forest areas in which only two to fifteen percent of the sunlight is able to pass through the canopy. Plant growths are usually the herbaceous types that grow large leaves in order to capture as much sunlight as possible. Here, the trees grow up to 60 feet above the ground.
The Canopy – These are the trees that rise up to 60 to 90 feet above the ground and whose crowns tend to crowd. The branches and leaves form a continuous canopy or awning-like cover for the plants and rainforest animals living in the understory and the forest floor layers. Other plants hang from its branches such as the vines that knot the trees together.
The Emergent Layer – These are the tall trees that loom above the thick canopy and form enormous mushroom-shaped crowns. They have the ability to withstand strong winds, intense heat, high temperature and low humidity.
The Significance of Forest Canopy to Animal Life
Generally, the diversity of plant and animal life in a rainforest depends on the forest canopy. The foliage of a full canopy has the capability to block as much as ninety-eight percent of sunlight, and this makes the forest floors more suitable for animal habitation.
However, a forest canopy could be affected by its geographical location, for which, a rainforest may be classified as temperate or tropical. In which case, the weather or climate changes the make-up of the canopy and its forest floors.
In other cases, the rainforest could be classified as primary or secondary, which indicates the present condition of the woodlands and the quality of its canopy. A reference to primary means that the woodlands have remained in their original conditions. They are hardly affected by any form of human activity and are also known as old-growth or virgin forests.
Woodlands that fall under the secondary category have in some ways degenerated. As such, they have less of the structured canopy that is important to rainforest diversity. They are currently undergoing regeneration either naturally or through human tree-planting assistance. Human activities such as selective logging, slash and burn agriculture or the ecologic and economic activities of the indigenous cultural communities that reside in the forest surroundings cause forest degeneration or denudation.
However, not all rainforests that have thick forest floor growths are secondary since there are tropical rainforests which allow sunlight during periods of seasonal variations. Hence, there is also the need to make a distinction between tropical or temperate rainforests.
Wildlife in the Temperate Forests
Temperate forests are found in the northern and southern hemispheres of the globe where they grow between the tropical and Polar Regions. As such, most of the animal species that thrive in their woodlands enjoy a moderate climate, and the areas go through four different seasons, namely: winter, spring, summer and fall.
During winter, the wildlife in these woodlands relies on their survival skills to stay alive and to avoid the blanket of snow that covers much of the forest. Wildlife slowly comes back by springtime as insects begin to hatch new eggs. These provide nourishment for the returning migratory birds and for the awakening reptiles and rodents that went through a period of hibernation.
The temperate forest comes into full life during summer as the forest turns green and becomes abundant with food. This is also the period when all animal denizens are quite busy scavenging for food, while others give birth to their offspring.
As fall sets in, daylight becomes shorter; hence, forest temperatures begin to drop and the deciduous trees begin to lose their chlorophyll. The leaves change color from orange to yellow to red and finally, to brown. This occurrence serves as indicator to forest dwellers that it’s time for them to gather nuts and seeds to store as a food supply for the upcoming winter.
The Tropical Forest as Wildlife Habitat
Plant and animal wildlife in tropical forests exhibit an overwhelming array of diversity as tropical woodlands have different altitudes and latitudes as well as soil, climate and flooding conditions. Most tropical rainforests are found in South and Central America, Australia, Africa and Asia with the largest being the Amazon, which is in South America.
The fragmentations of the rainforest habitats into smaller patches have affected some of the animal species. Roads have cut through the forest to literally pave the way for logging, mining and farming transport for these industries.
As a result, some of the animal species are isolated and kept away from their potential mates. The open habitats pose danger to their safe existence as they become targets for poachers or hunters. Hence, a large number of animal species living in rainforests found in tropical regions have become endangered.
Below are some examples of popular species of animals which live in rainforests with brief descriptions of how they survive and adapt to their environment.
The Australian Marsupials
There are about 140 different marsupials that are commonly found in Australia’s temperate forests. The most distinctive characteristic of this animal is the manner in which it gives birth to its young. They bear live but underdeveloped newborns after a short period of pregnancy and complete the development process inside their marsupium or pouch. The newborn attaches itself to a teat inside the pouch and goes through a long period of gestation in order to complete their development process.
A koala is a type of marsupial that is often mistaken for a bear because of its large and furry stout body. Its arms are equipped with strong powerful claws, which it uses for tree-climbing since it dwells in the highest branches of eucalyptus trees. Koalas spend most of the day atop the gum trees either sleeping or simply lazing about. They become active for a few hours during the night and feed on eucalyptus leaves or groom their bodies.
During hot weather, they tend to dangle their limbs to keep cool but will curl-up like a ball to conserve their body heat during colder seasons. They also have the natural instinct of knowing how to swim or jump from tree to tree in order to survive occasional flooding.
The name koala is an aboriginal word that means “without water” since they rarely find it necessary to drink water due to their leafy eucalyptus diet. However, not all types of eucalyptus are suitable for these marsupials; hence, they make it a point to sniff the leaves to make sure that they are the right variety.
Other Australian marsupials include kangaroos, opossums, wombats, numbats, bandicoots and bilbies.
The Amazon Insects
Insects are the largest group of animals that live in the tropical forests. It is estimated that more than 90 percent of the animal kingdom in the Amazon rainforests are represented by insects. Accordingly, there are about 50,000 species living in every square mile of the woodlands while 25 percent of the world’s animal species are said to be beetles.
The Longhorn Beetle
The Longhorn Beetle (Titanus Giganteus) was named as such because of its long antennae (up to nine inches long when extended) and a body length of about 16 centimeters or 6.3 inches, which makes it the largest known beetle species in the Amazon. Its mandibles are incredibly powerful and capable of snapping wood or even flesh into smaller chunks.
They thrive unobtrusively in the warmest parts of the jungle and are regarded as harmless to humans. The male adult beetles are believed to be non-eaters of any kind of food and are more active in seeking out mates.
It is said that they have stored enough food supply in their systems during their larval stages as they subsist and developed in the roots of dead hardwoods. Not surprisingly, the approximate life expectancy of the adult male species is seven weeks.
Continue to page 2 for more examples of animals, which live in rainforests
The Amazon Insects (continued from page 1)
The Blue Morpho Butterflies
The Amazon rainforest is also known for having the most diverse species of butterflies and one of the most popular is the blue morphos . They are among the largest butterfly species in the world and their wings span from about five to eight inches.
The size and the incredible incandescence of this butterfly’s wings are noticeable even from a distance of about one-half mile away. However, the undersides of their wings are a dull-brown, and this serves as their camouflage against predators such as birds and other insects.
They spend most of their time on the forest floors and stay among the shrubs or in the understory trees, often with their wings closed. However, they have been observed to fly across all the forest layers when in search of mates or to commune in large groups high above the treetops.
Their entire lifespan is estimated at 115 days, which is spent partly during the caterpillar stage eating a variety of leaves. As adult butterflies, they use their proboscis for sipping the juices of rotting fruits, tree sap or even mud or the juices of decomposing animals. Their existence is largely threatened by deforestation and by humans who sell butterflies to collectors.
The Mammals of Asia
The Orangutans of Borneo and Sumatra
The most famous mammals of Borneo are the orangutans, which are believed to be found only in the islands of Borneo and Sumatra. To date, there is great concern about the endangerment of this animal species, although it was reported in 2009 that conservationists had discovered about 219 new nests, which roughly equates to an additional 2,000 for the orangutan population.
The name orangutan is a Malay word referring to a “person of the forest”. They are orange-haired primates and regarded as highly intelligent mammals. They stand at about five feet in height but their stretched arms can reach farther than their height (seven feet) and touch the ground. The largeness of their arms helps them climb up to the top of the trees where they have been observed to spend 90 percent of their time. Their diet includes mostly fruits and leaves although they also eat tree bark, insects and occasionally some meat.
An orangutan infant bonds strongly to its mother and stays with the latter for up to six or seven years until they master their survival skills. Hence, female orangutans give birth only once every eight years, which is the longest for any animal.
Adult males are loners who make rumbling and howling sounds while they forage for food. These sounds are their way of expressing their desire to be left alone or for others to stay away. Although studies confirm that they can survive up to 60 years even while in captivity, their species are at risk and in danger of extinction due to widespread deforestation and human hunting activities.
The Asian Elephants
The pygmy elephants of Borneo are the most endangered mammalian species in Asia. Large patches of the forest have been lost to these elephants as the areas are now being used for logging and oil palm plantations. As a result, accesses to these areas have been cut-off by roads, while the elephants that dare to trek the open pathways become the victims of hunters and poachers.
Elephants usually travel in herds, but the roads prevent them from catching up with other family groups. Other rain forest areas have been used as settlements and agricultural sites although the local farmers have oftentimes found their plantations ravaged and trampled by elephants looking for food.
The tusks of Asian elephants are carried by the male adults and are relatively smaller than those of their African counterparts, while some adult male elephants are even tusk-less. They flap their ears constantly to cool down. They are often found near rivers because water and salt minerals are essential to their diets.
Losses of habitat and food scarcity are the largest threats to their existence since they have to compete and come into conflict with the growing human population. Such conflicts result in the loss of human lives, which causes humans to retaliate by slaughtering the elephants before they can do any damage.
Rainforest Amphibians and Reptiles
Frogs are the best known tropical rainforest amphibians, and they are mostly tree-dwelling inhabitants. This makes them different from the frogs in temperate rainforests that usually inhabit areas near bodies of water and on the forest floors.
Another difference between temperate and tropical frogs is their breeding habits. Frogs in the temperate forests leave their eggs in water, but the eggs are at risk from aquatic predators such as fish and shrimp. The tropical frogs lay their eggs in tree vegetation, which overhangs a body of water. The vegetation keeps the eggs moist until they hatch into tadpoles, which drop right into the water below.
This is how the glass frogs, a species that is native to the Amazon rainforest, propagate. Their scientific name, which is “hyalinobatrachium pellucidum”, means translucent skin; however, they are typically lime green. Their sizes range from about one to three inches while their heart, liver and intestines are visible since their abdominal skin remains transparent. However, frog species whether temperate or tropical dwellers are among the endangered animals due to a deadly disease called “chytridiomycosis”.
Most boa constrictors are found in Mexico and Argentina and make their habitats in deserts, wet tropical forest, open savannas and even cultivated fields. They are active at night and use their heat-sensitive scales to hunt for prey. They can grab small birds or bats as they fly by in the air. Ordinarily, they feed on opossums, mongoose, large lizards, rats and squirrels after they constrict or suffocate them.
Most constrictors found in rainforests stay in the canopy and are rarely seen or encountered by humans due to their camouflage abilities that allow them to blend with the color of the foliage.
The distinguishing and interesting feature of toucans is their bills, which measure about seven and one-half inches. Even though these are huge and enormous, they are composed of honeycomb-structured bones that contain mostly air. Hence, toucans cannot use them as formidable weapons against predators.
The toucan’s bill is used mainly for feeding purposes to reach for the fruits that are attached to smaller branches. They are also useful for catching lizards, insects, and even young birds. However, toucans are not born with large bills, the bills develop into their full-size as the birds grow to adulthood.
They dwell in the forest canopy but may build their nests inside tree holes. Although their bright colors allow them to stay camouflaged within the canopy, a flock of toucans often draws attention to themselves by making a cacophony of sounds.
These characteristics make them quite attractive to bird collectors, although the indigenous people regard them as sacred. Local beliefs are that the toucans serve as a communication medium between the living and those that have transcended into spiritual form.
Harpy Eagles are recognized as one of the world’s largest and most powerful species of eagles. Their hind talons are reputed to be the same size as a grizzly bear’s claws. These eagles are most at home in tropical forests like those found in Mexico, Argentina and Brazil.
Their size is measured at about 35 to 41 inches in terms of body length and six and half-foot in terms of wingspan. An average Harpy Eagle can weigh as much as 10 to 20 pounds, but a female can weigh twice as much. However, the weight of the prey which a Harpy can carry-off to its lair is limited to half of its own body weight.
Their preys are mostly tree-dwelling animals such as monkeys, sloths, opossums, birds and snakes. However, they often have to use their skills in maneuvering their flight since they have to pursue their prey through the trees.
Harpy Eagles build their nests in the emergent layers of the forest and ordinarily lay only one to two eggs. Curiously, only one of the two eggs is desired by a Harpy mother. This means that if one has hatched, the mother ignores the second egg and gives it no further support to complete its hatching process.
The name Harpy was derived from the mythical Greek figures called "harpies", which are winged creatures with a vulture’s body, sharp claws and a woman's face.
The Earth’s rainforest cover has decreased from 14 percent down to a remaining 6 percent where millions of the world’s animal population can be found. About half of the original tropical rainforests, which are in the Latin American and Southeast Asian regions, have been destroyed. The other half, which is found along the equator, still face great danger from mankind’s increasing activities.
As the sizes of these forests are reduced through man’s relentless exploitation, so are the numbers of animals which live in rainforest environments.
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- Image: Tropical forest canopy at Eden Looking down from a high point by M J Richardson –Wikimedia CCA-SA 2.0 Generic
- Image: Boa Constrictor in belize jungle it was about 9 feet long by Belizian
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- Image: :Australia Cairns Koala by Guillaume Blanchard Wikimedia CCA-SA 1.0 Generic
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- Image: In a forestry plantation – geograph.org.uk by David Baird CCA-SA 2.0 Generic
- Image: Borneo Elephant (Elephas maximus borneensis) by PLoS Biology
Wikimedia CCA-SA 2.5 Generic
- Image: Abernethy Forest – geograph.org.uk by Richard Webb –Wikimedia CCA-SA 2.0 Generic
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- Orangutan Pongo pygmaeus- National Geographic — http://animals.nationalgeographic.com/animals/mammals/orangutan/
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- Image: Forest on Barro Colorado by Christian Ziegler. CCA 2.5 Generic
- Image: Borneo Orangutan (Pongo pygmaeus) Femal by Julielangford Wikimedia CCA-SA 2. 5 Generic
- Image: Ramphastos toco by Daph Chloe Wikimedia Commons CCA-SA 2.0 Generic
- Image: Photograph of a Blue Morpho butterfly by Gregory Phillips Wikimedia CCA-SA 3.0 Unported
- Image: Hruedai dorso by D. F. Cisneros-Heredia Wikimedia CCA-SA 2.5 Generic
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- Image: Harpia harpyja -Belize Zoo-8-3c by Snowmanradio Wikimedia Commons
CCA-SA 2.0 Generic