What does it mean for a species to be endemic?

A species is termed endemic when it is found exclusively within a specific geographic area. This means that the species is native to that particular location and is not naturally occurring anywhere else in the world. Endemism is often related to unique environmental conditions, such as climate, soil, or geography, which allow certain species to thrive only in those specific regions. This concept is important in the study of biodiversity and conservation, as endemic species may be more vulnerable to extinction due to their limited distribution and specialized habitat needs.

The other choices describe different characteristics of species but do not pertain to the definition of endemism. For example, the notion of being widespread across multiple continents refers to species that are adaptable and can survive in various habitats around the globe, which contrasts with the exclusivity defined by endemism. Active during both day and night describes a species' behavioral pattern, and living in marine environments relates to a species' habitat but does not encapsulate the specificity of geographic limitation inherent in being endemic.