Endemic: Restricted to a particular place. Means the animal lives in a certain place and nowhere else.

Endosymbiotic: Being symbiotic and living within the body of an individual of the associated species.

Entoprocta: An animal phylum that includes organisms with tentacles on a cup shaped body supported by a single stalk.

Environment: The set of conditions surrounding someone or something.

Environmental Stress: Variously defined as (1) an environmental change to which an organism cannot acclimate and (2) an environmental change that increases the probability of death.

Epibenthic (epifaunal or epifloral): Living on the surface of the bottom.

Epidemic Spawning: Simultaneous shedding of gametes by a large number of individuals.

Epifauna: Animals living attached to the sea bottom or moving freely over it.

Epipelagic Zone: The 0- to 150-m-depth zone, seaward of the shelf-slope break.

Epiphyte: Microalgal organism living on a surface (e.g., on a seaweed frond).

Erosion: The process by which wind, water or ice wash away or otherwise remove soil, stone, crop residues, or organic matter from the land surface. Water droplets begin the erosion process by detaching soil particles. Runoff waters transport the detached particles to local and regional streams or lakes. Soil erosion represents the single largest source of nonpoint pollution in the United States.

Estuary: Where the ocean and rivers meet and mix, creating a semi-enclosed body of water that has a free connection with the open sea and within which seawater is diluted measurably with freshwater that is derived from land drainage. Estuaries are very important for fish and shellfish production, especially in providing nursery habitat.

Estuarine Flow: Seaward flow of low-salinity surface water over a deeper and higher salinity layer.

Estuarine Realms: Large coastal water regions that have geographic continuity,are bounded landward by a stretch of coastline with fresh-water input, and are bounded seaward by a salinity front.

Etiolation: The formation of weak, spindly foliage deficient in Chlorophyll, usually occurs in light of too low intensity.

Euphausiid: A planktonic, shrimplike crustacean.

Eutrophic: Bodies of water or habitats that have a high concentration of nutrients, which is harmful to normal fish populations.

Eutrophication: The process of surface water nutrient enrichment causing a water body to fill with aquatic plants and algae. The increase in plant life reduces the oxygen content of the water. Eutrophic lakes often are undesirable for recreation and may not support normal fish populations.

Evapotranspiration (ET): The process of changing soil water into water vapor through the combination of soil evaporation and plant water use, or transpiration.

Evenness (E): A measure of how similar the abundances of different species are in a community, as opposed to strong dominance by one or a few species.

Exoskeleton: The external body wall of arthropods.

Explosive Fishing: A method of fishing, which uses chemicals that explode in the water in order to kill fish or marine life.

External Filter: Any filter not kept inside the aquarium, but connected to it by hoses. Canister filters are an example of these.

Eyespot: A coloration on the body of an animal that looks like an eye and serves to fool predators as to the location of that animal's head; a type of defense mechanism employed by animals.