The benthic zone is one of the ecological regions of water, located at the bottom of any marine or freshwater body, such as a river, ocean, lake, or pond. It is included under the limnetic zone, which means in the benthic region, water is very deep, and amount of oxygen gas and light is in limited quantity. Organisms living in benthic zone are called benthos, which includes microorganisms as well as larger invertebrates. In deep lakes and seas, the benthic zone is in perpetual darkness. In shallow waters, light does penetrate.

Flag trees, otherwise called banner trees, are living weather vanes. They help in determining the direction of the prevailing wind of a particular location. On mountain ridges, where trees are constantly exposed to strong winds, the windward facing branches of a tree are often stunted or killed. On the other hand, on the leeward side (facing away from the wind.), the trunk shelters the branches, giving the tree a characteristic flag-like appearance.

A large naturally occurring community of flora and fauna, inhabiting a major habitat, exhibiting common characteristics is called a biome. Temperature and precipitation are the two most influencing factors responsible for the biome formation. Tropical rain forest. Grassland, Alpine tundra, etc., are examples of major biomes.

Detritivores or detrivores are heterotrophic organisms that obtain their nutrition by feeding on detritus. Detritus is the organic matter made up of dead or decomposing remains of plants and animals, including faeces. Examples of detrivores are millipedes, earthworms, termites, Snails, etc.

The organisms which can tolerate only a narrow range of salinity are called stenohaline. They are unable to withstand wide fluctuation in the salinity. Due to this property, many seawater animals can not live long in freshwater and vice versa. Some examples of stenohaline animals are shark, goldfish, etc.