The spiny butterfly ray or giant butterfly ray (Gymnura altavela) is a species of butterfly ray, family Gymnuridae, native to the shallow coastal waters of the Atlantic Ocean. A large ray that can measure over 2 m (6 ft 7 in) across, it may be distinguished from the sympatric smooth butterfly ray (G. micrura) by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.