A group of diverse organisms that primarily inhabit water bodies, ranging from oceans to freshwater environments. This category includes all forms of life that thrive in water such as Platyhelminthes, a class of simple, soft-bodied invertebrate animals; Arthropods, invertebrates with an exoskeleton, segmented body and paired jointed appendages; and Amphibians, a class of cold-blooded vertebrates that spend some of their life in water and some on land. All these organisms fall under the broader classification of animals.