Because there are so many creatures
living in the rainforest, there is a great deal of competition for food,
sunlight and space.
Some animals became very
specialised. This means that they adapted to eating a specific plant or
animal that few others eat. For example, parrots and toucans eat
nuts, and developed big strong beaks to crack open the tough shells. Leafcutter ants climb
tall trees and cut small pieces of leaves which they carry back to their
nest.The leaf pieces are about 50 times their weight.The ants bury the leaf
pieces, and the combination of the leaves and the ants' saliva encourages the
growth of a fungus, which is the only food these ants eat.
Sometimes there are relationships
between animals and plants that benefit both. Some trees depend on animals to
spread the seeds of their fruit to distant parts of the forest. Birds and
mammals eat the fruits, and travel some distance before the seeds pass through
their digestive systems in another part of the forest.
One problem with specialisation is that if one species
becomes extinct, the other is in danger too unless it can adapt in time. The
dodo, a flightless bird of Mauritius, became extinct in 1681. Today there are
just 13 calvaria trees left on the island, each over 300 years old, and
nearly at the end of their life. Scientists realised that the seeds had to pass
through a dodo's digestive system before they could germinate. It seemed that
the tree species would also become extinct, but scientists tried domestic
turkeys and have successfully managed to germinate some seeds.Many
rainforest animals use camouflage to 'disappear' in the rainforest. Stick
insects are perfect examples of this. There are some butterflies whose wings
look like leaves. Camouflage is of course useful for predators too, so that they
can catch prey that hasn't seen them. The Boa Constrictor is an example of a
camouflaged predator.
The South American three-toed
sloth uses camouflage and amazing slowness to escape predators. Green algae
grows in the sloth's fur, which helps camouflage it in the forest canopy. Sloths
are among the slowest moving animals of all (inside too, as it takes about a
month to digest food). They hang from branches in the canopy, and are so still
that predators such as jaguars don't see them.
Some animals are poisonous, and use
bright colors to
warn predators to leave them alone. There are several species of brightly
colored poison arrow frogs. Native Central and South American tribes used
to wipe the ends of their arrows onto the frog's skin to make their arrows
deadly