animal fish or lower water animal An aquatic animal is an animal, either vertebrate or invertebrate, which lives in the water for most or all of its lifetime. This is equivalent to: 'fish (food source)' or 'shellfish (food source)' or 'crustacean (food source)' or 'echinoderm (food source)' or 'coelenterate (food source)' However, this disjunction appears to be a burden on reasoners, and so this is currently not implemented. fish species shellfish species coelenterate requires discussion