FishFish are cold blooded, live in water and are covered in scales. They breathe through gills located on the sides of their heads. Their gills take oxygen out of the water around them so they can breathe. Their limbs, if they have any, are in the shape of fins and do not have digits. They exhibit greater species diversity than any other group of vertebrates, with over 32,000 known species.
Fish live in oceans and freshwater ecosystems. Well adapted to their water world, fish secrete a special type of mucus from their skin. The slime coating helps them move through water faster, protects them against parasites and diseases and covers wounds to prevent infection.
Fish orient themselves using landmarks and mental maps based on multiple landmarks or symbols. They possess spatial memory and visual discrimination.