Is there a difference between exotic and invasive species?

December 2005

Yes. Although the terms are often used interchangeably, there is a difference. All invasive species are exotic, but not all exotic species are invasive.

Venomous lionfish (Pterois volitans), native to the Indo-Pacific, were discovered in North Carolina waters in 2000. Their populations continue to increase, as they prey on native fish species.

A species is usually considered invasive if it causes damage to an established ecosystem. Some invasive species overrun areas and replace one or more native species.

An exotic species is any organism not native to an area, but not necessarily found in the wild. It may have been brought intentionally or introduced accidentally. It can be found in homes, private gardens or public facilities, such as zoos and aquariums. Occasionally, exotic species escape and establish themselves without causing damage to the natural environment. Both plants and animals can be exotic and/or invasive.

An example of an invasive animal species is the nutria (Myocastor coypus), a large, rat-like mammal introduced from South America for the fur industry in the 1930s. Nutria escaped from fur ranches in Louisiana and spread to many other states. Semi-aquatic, they have adapted well to life in coastal marshes, and because of their feeding habits they have caused extensive damage to vegetation and dune ecosystems.

An exotic plant that has become invasive after being introduced into North Carolina’s aquatic habitats is the giant salvinia (Salvinia molesta). Originally from Brazil, it was first detected in 2000 as an escapee from private water gardens. Giant salvinia is considered highly invasive. It forms large, floating mats and blocks sunlight and depletes oxygen in water. This can cause die off of native species and foul water intake pipes.

Though not all exotic species are invasive, it’s recommended that importation of exotic species be minimized to prevent unwanted effects on the local ecosystem. Before adding a plant or animal to your home or garden, be sure to do your research and find out if it is native to your area.