The emergent layer is located above the canopy and is exposed to the most sunlight. Because of this, trees, shrubs and plants of many different varieties located below struggle to reach the light. Trees that make use of the emergent layer are very top-heavy and have almost no branches in lower areas; their trunks' average diameter is 16 feet. A multitude of butterfly, bird and monkey species make their home in this layer.
The canopy layer is the primary layer of the forest, forming a roof over the two layers located 60 to 90 feet below. Trees that form the canopy tend to be broad and close together, forming a continuous covering of tree crowns that are themselves covered in other plants and vines. Many animals live in this area, since food and sunlight are abundant. The canopy is home to 90% of all organisms found in the rain forest, including various species of snakes, toucans and treefrogs.
The understory layer is dark, receiving only 2 to 15 percent of the sunlight that falls on the canopy. This layer contains young trees and leafy herbaceous plants that are able to thrive in low light, such as ferns. Because light in the understory layer is so scarce, only areas lacking trees in higher layers see sunlight sufficient to allow vegetation growth to become dense and impenetrable.
The forest floor is extremely dark, receiving less than 2 percent of the sunlight located above the emergent layer. Because of these conditions, little vegetation grows here except for plants that have adapted to thrive in very low light. The forest floor is composed of a thin layer of fallen leaves, seeds, fruits, and branches that quickly decompose due to the lack of sunlight. Animals such as giant anteaters inhabit this layer.
