How has the flora and fauna of the rainforest adapted to their environment?

by josh-es (student)

More species of flora and fauna live in rainforests than in any other habitat on earth. Scientists believe that this is because the rainforests are the oldest ecosystems on the planet, with some forests in Asia dating to around 100 million years ago. Also, due to the location of the rainforests, the ice ages did not reach or affect them, but made many other species in other areas extinct. But this large variety of flora and fauna also means there is much competition for survival, and how have the flora and fauna adapted to their environment?

Fauna is the term referring to animal life living in a region. In rainforests, there are thought to be about half of the world’s animal species. Over 500 mammals, 175 lizards and over 300 other reptile species, and one third of the world's birds live in Amazonia. It is estimated that about 30 million insect types can be found here. These animals have adapted in many ways to survive in and make good use of its habitat.

Flora refers to the plant life living in a region. In rainforests, the variation of the flora is extremely extensive, with about half of the earth’s plant species again living within them. In fact, the rainforest is sometimes called the ‘Lungs of the Earth’ because it is estimated that its plants recycle about 20% of Carbon Dioxide into Oxygen.

Adaptation is the process in evolution by which a population becomes better suited to its habitat. This process generally takes place gradually over generations. In all habitats, animals have adapted to their habitats to aid their competition for survival. For example, Polar Bears have evolved very thick coats to keep them warm in Arctic climates. Also, Camels have evolved methods of storing water; something which the desert does not provide very often. But flora and fauna of the rainforests have adapted perhaps more than any other habitat, perhaps simply due to the sole amount of competition there is between all of the population of the forests.

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The number of species alone may explain most of the evolution of the fauna in the rainforest. Competition for food and water supplies is fierce. This may explain why over millions of years of evolution so many highly adapted species have evolved in the canopy of Amazonia. Toucans and Parrots are examples of this process. The fruits and nuts from many trees have evolved with a tough shell to protect them from predators. In turn toucans and parrots developed large strong beaks, which serve as nutcrackers. This gives these birds a large advantage in competition over birds with smaller beaks. Animals have also adapted to protect themselves from predators. Some butterflies look like leaves when they close their wings, for example. Predators also take advantage of camouflage, such as the Boa Constrictor, which can move on prey unnoticed as it blends in with trees. Other animals, such as the coral snake, have also evolved deadly poisons to both attack its prey (coral snakes eat smaller snakes, lizards and frogs) and to protect itself from possible predators, and are brightly coloured to warn predators. Coral Snakes usually attempt to flee before they attack; and despite their venom being the most deadly in North America, there are only usually between 15 and 25 deaths per year anywhere in the world, compared to an estimated 800 deaths from the Russell’s’ Viper in Burma alone (but the snakes with the deadliest venoms often prefer fleeing, the Black Mamba of Africa has similar behaviour). The Jaguar has also adapted traits to help it catch prey in the rainforests: it can both swim and climb. Climbing isn’t uncommon within the Felidae family (all ‘cats’ belong to this family) to which the Jaguar belongs, as tigers and leopards can also climb, but swimming is somewhat uncommon. This climbing and swimming allows the Jaguar to catch prey from pouncing down from trees as well as to escape possible predators by climbing. It also allows Jaguars to prey on animals in the trees, such sloths, (although its slow movement makes it difficult to detect) but this is less common. Its swimming trait also allows it to catch fish from the Amazon River and its tributaries. The Jaguar has also adapted a very powerful bite, even relative to other cats, which allows it to break through tough substances such as turtle shells and also has slightly different hunting techniques to those common to most other similar cats.

The flora of the rainforests has also adapted to help them survive the somewhat harsh habitat of the rainforest. The plant life in the tallest layer of the forest, the emergent layer, has very wet, windy and hot conditions as it is more exposed than the layers towards the forest floor. Trees in the emergent layer have adapted leaves with a waxy surface to hold water for photosynthesis (their leaves are small, so they need to absorb as much water as possible), for example, and have winged seeds as a method of dispersal, taking advantage of the wind and rain. Their leaves are also small to protect them from heating up too much. The main layer of the forest is the canopy below the emergent layer. These plants have leaves with ‘drip tips’ to prevent mosses and fungi from growing on them. The leaves are also very dense to filter out as much sunlight as possible. Epiphytes are also found on this layer, and these are plants that live in branches of trees, and grow vines down them to the ground level. This allows them to use the support of the trees to grow towards the light source, and therefore to get more sunlight than they would if they lived closer to the forest floor. The understory, the next layer down, gets just 2%-5% of the sunlight. Therefore, these plants have very large, dark green leaves (because they have much more chlorophyll in them) allowing for the leaves to absorb as much of what is available as possible. The forest floor gets up to 2% of the sunlight, and so almost no plants grow here. What is found is mainly fauna but there is also much decomposing plant and animal life on the forest floor, and when it is broken down it releases nutrients important to plants. Plant roots have adapted to this, having roots close to the surface to take advantage of the decomposition.

In conclusion, all fauna and flora have adapted to their rainforest habitat to help them survive and compete with the rest of the population of the forest. Despite this, the rainforest is less explored than the sea bed, and scientist may not even know half of the plants and animals that live there. There is also a lot more to discover there. For example, 121 prescription drugs across the world are made from plants in the rainforests, and development on drugs from these plants for serious diseases such as AIDs and Cancer is going on, but only about 1% of known plants in the rainforests have been tested. Despite this, deforestation is a major problem, and many species, with an estimated 50,000 animals becoming extinct every year in the amazon due to this problem and to others, are gone before we even know about them.

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