This sea cucumber is somewhat unusual in appearance in comparison with other sea cucumbers (and even within its family), as it looks more like a jellyfish with its large umbrella-like swimming structure supported by a ring of around 12 highly modified oral tentacles, its small tapered body and its swimming position with the mouth on top.

[1] The mouth is surrounded by around 15 short feeding tentacles like any sea cucumber, and the veil can be contracted like jellyfishes do (it is interrupted at the central ventral radius).

[1] This sea cucumber is extremely rare, but its geographic range seems very wide: it has been collected in the Atlantic, Pacific and Indian oceans, between 200 and 4,433 m of depth.

[1] This species was described by Hubert Jacob Ludwig in 1893 based on trawled specimens collected in 1891 by the USS Albatross between the Gulf of Panama and the Galapagos Islands (605–3,350 m deep).

[1] In 2011, the American scientific expedition NOAAS Okeanos Explorer photographed what scientists first believed to be an unknown jellyfish,[4] but the picture was formally identified in 2014 by Smithsonian Institution experts Christopher Mah and David Pawson as Pelagothuria natatrix.