Aquatic organism refers to any plant or animal which lives at least part of its life cycle in water.
Aquatic organism means an individual member of any species of fish, mollusk, crustacean, aquatic reptile, aquatic amphibian, or aquatic insect or other aquatic invertebrate. Aquatic organisms can be divided into 3 broad groups: plankton, nekton, and benthos. Planktons are tiny aquatic organisms that cannot move on their own. Nektons are aquatic animals that can move on their own by “swimming” through the water. Benthoses are aquatic organisms that crawl in sediments at the bottom of a body of water.