La Selva means "the forest" in Spanish and that is just where we're going! Located in the Caribbean lowlands of northern Costa Rica, La Selva is a biological reserve consisting mainly of primary forest and abandoned plantations.

Ecologists, Dr. Lee Dyer and Dr. Grant Gentry have been working at La Selva for many years. Dyer explains, "It was our concern about disappearing wild areas of the world that led each of us to focus our research in the rainforest." The scientists' objective is to document the diversity of caterpillars and understand their impact on the rain forest ecosystem. Earthwatch teams help find and raise the caterpillars.

Most of the forest at La Selva is considered tropical wet forest with an average rainfall of 12 to 13 feet a year. Because it is so close to the equator, the climate is warm and humid. The forest supports a remarkable diversity of animals and plants.

From top to bottom, each layer of the rainforest provides a completely different habitat for different organisms to thrive. The canopy, for example, is made up of the tops of very tall trees and receives direct sunlight, rain, and wind. The forest floor is shaded and receives the rain indirectly as it trickles down through many layers of leaves. Tropical rain forests are famous for their biodiversity.

La Selva is home to over 2,000 species of plants. More than 100 species of trees can be found in a 5-acre (2-kilometer) plot. This is certainly a lot more than the 12 or less trees found in a temperate forest. Do you know how many different trees can be found in your area?

There are also hundreds of birds and mammals. On a typical walk you will see peccaries, coatis, sloths, monkeys, toucans, parrots, and at least a dozen species of butterflies. Scientists estimate that there are over 5,000 species of caterpillars at La Selva.

Photos courtesy of Shauneen Giudice/Earthwatch Institute