What is a Cosmopolitan Species?
In the fields of biology and geography, a species is referred to as "cosmopolitan" if its geological distribution is exhibited in all regions if not most regions of the globe.
Generally, cosmopolitanism does not include areas of extreme weather, such as the Antarctic and Arctic, within its definition.
If a species does not experience cosmopolitanism and is confined to a geographical location, it is called endemic. Sub-cosmopolitan is a term which is used to describe the state between endemism and cosmopolitan. This phenomenon is caused by gaps in a species' distribution causing it to fall in between the endemism and Cosmopolitan categories.
Ocean and Land Cosmopolitanism
Several physical and biological barriers affect the habitat of the oceans and which species can live within them. One of such biological boundaries is temperature range which affects free movement of a tropical taxon of species between the Atlantic and Pacific oceans. There are higher chances of cosmopolitanism on the land than in the ocean.
Examples of Cosmopolitan Species
Both modern and ancient species can exhibit cosmopolitan distributions. Before their extinction, several species of dinosaurs were once considered to be cosmopolitan including the Lystrosaurus. In modern times, the killer whale is considered to be one of the most cosmopolitan species on the planet. This puts them in a category which includes cats, humans, orchids, and dogs.