Aquatic Animals
Longfin sculpin ( Jordania zonope ) An aquatic animal is an animal , either vertebrate or invertebrate , which lives in the water for most or all of its lifetime. Many insects such as mosquitoes , mayflies , dragonflies and caddisflies have aquatic larvae , with winged adults. Aquatic animals may breathe air or extract oxygen that dissolved in water through specialised organs called gills , or directly through the skin. Natural environments and the animals that live in them can be categorized as aquatic (water) or terrestrial (land). This designation is paraphyletic . The term aquatic can be applied to animals that live in either fresh water ( fresh water animals ) or salt water ( marine animals ). However, the adjective marine is most commonly used for animals that live in saltwater, i.e. in oceans, seas, etc. Aquatic animals (especi...