Stygiomedusa

Stygiomedusa gigantea, commonly known as the giant phantom jelly, is the only known species in the monotypic genus of deep sea jellyfish, Stygiomedusa. It is in the Ulmaridae family. With only around 118 sightings in 110 years, it is a jellyfish that is rarely seen, but believed to be widespread throughout the world, with the exception of the Arctic Ocean. The Monterey Bay Aquarium Research Institute's remotely operated underwater vehicles have only sighted the jelly 27 times in 27 years. A study conducted by the Journal of the Marine Biological Association of the United Kingdom, focusing on four Stygiomedusa gigantea present in the Gulf of Mexico, revealed information regarding the wider distribution of this species. S. gigantea is thought to be one of the largest invertebrate predators in the ecosystem. It is commonly found in the ocean's midnight zone, and twilight zone usually at depths of 6,665 m (21,867 ft).