The whale shark is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The largest confirmed individual had a length of 61.7 ft. The whale shark holds many records for size in the animal kingdom, most notably being the largest living nonmammalian vertebrate. It is the sole member of the genus Rhincodon and the only extant member of the family Rhincodontidae, which belongs to the subclass Elasmobranchii in the class Chondrichthyes.

Source: Wikipedia