 Welcome to the tropical rain forest--home to nearly half of all of the earth's species of living things--where the climate is never too hot or too cold. For 60 million years, these ancient rain forests have been just right for an unbelievable number of plants and animals.
Covering 7% of the earth's surface, the tropical rain forest stretches around the equatorial belt. The animals and plants that live in the New World, or Neotropics, are quite different from those that live in the Old World tropics, which reach from West Africa to Australia.
Rain forests are bursting with life, and the problem for rain forest plants and animals is balance--how to share time, space, and food. Some rain forest animals are active at night; others, by day. Some live high up in the treetop canopy; others, near the ground. Some prefer dark hiding places; others, life in the open. The sheer number and diversity of insects found in the world's rain forests amazes and inspires scientists, environmentalists, and nature lovers alike. Read further to see just a few of the species that make the rain forest such a model of biological diversity, or biodiversity.
As many as half of the earth's life forms may live in the jungle canopy; most of them are insects. The upper canopy is the richest level. There, photosynthesis--the process by which sunlight nourishes plants--drives an explosive burst of life. More than half of the rain forest's plant and animal species are born, reproduce, and live their entire lives without ever touching the ground. Using a biodegradable insecticide aimed only at the rain forest canopy, scientists such as Terry Erwin of the Smithsonian Institution have been able to explore insect life in the far reaches of the canopy. From 19 trees in Panama, Dr. Erwin has collected more than 1,200 different species of beetles; in a single tree in Peru he found 43 ant species--more species than can be found in all the British Isles!
The rain forest crawls with ants of all kinds. Since they first emerged 100 million years ago, ants have had to deal with the same problems human societies have faced, including war, hunger, and environmental stress. The earliest ants were members of primitive hunting communities. The more advanced species are the great societies with highly specialized castes of workers and soldiers. Some herd other insects, some enslave one another. Ants are surpassed only by humans in the wide variety of ways in which they make a living.
Large leaf-cutter ants forage for leaves, flowers, and plant pieces to take back to the nest. There, small leaf-cutters chew the vegetation to a pulp to make fertilizer for the fungus that the ants eat. Leaf-cutters live in colonies of three to four million individuals dwelling in thousands of underground rooms. Through their pruning and nesting habits, they enrich the soil around them.
Millipedes (Order Diplopoda) are important decomposers on the forest floor, feeding mostly on rotting wood and dead leaves. Nearly all millipedes produce toxic chemicals, such as hydrogen cyanide, when provoked.
Giant cockroaches (Blaberus giganteus) live in forest litter and tree hollows. The young are found in guano, or bat droppings, at the bases of trees. Like most cockroaches, they prefer night to day.
While we may consider termites pests, they are important recyclers of nutrients in the lowland rain forests. Without termites and ants, the jungle would soon smother in its own litter. Epiphytes--plants such as ferns, bromeliads, and orchids that use trees or cliff walls for support--provide sometimes surprising arthropod microhabitats, that is, habitats within habitats. Some bromeliads serve as aquariums, with a capacity of over 7 liters (2 gallons) of water. Bromeliad life is often crowded: beetle larvae, spiders, sow bugs, cockroaches, and pseudoscorpions can coexist in the same plant. Many rain forest mosquitoes (family Culicidae) breed only in bromeliad tanks.
Damp, dark tropical caves create rich environments for the arthropods that live there. Temperature and moisture are constant year-round and there is always plenty to eat. Cave arthropods often are blind and rely on their sensitive antennae to guide them. Bats supply huge populations of cockroaches and other arthropods with thick, edible carpets of bat droppings, or guano.
Spiders (Class Arachnida) and cave crickets (family Gryllacrididae) thrive in zones of high humidity and constant pools of standing water.
The Peripatus (Phylum Onychophora) has changed little in 500 million years. Although it is not an arthropod, some consider it to be an ancient link between insects and worms. Eyeless and colorless, arthropods dwelling deep in the cave live in complete darkness all their lives. Their antennae take over in the quest for food. Crustaceans such as tiny isopods (Order Isopoda) and amphipods (Order Amphipoda) creep slowly across pool bottoms while crayfish (Order Decapoda) feed on floating debris. You can listen to the sounds of the rain forest. Please note: these files may take time to download.
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