''Saccopharynx ampullaceus'', referred to as the gulper eel, gulper, taillight gulper or pelican-fish, is an

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

-dwelling eel found in the North

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...

. They are found up to a depth of .Fishbase.org
Retrieved April 7, 2016 These fish are rarely observed, so little information is currently known about their habits or full distribution.

Type specimen

In the fall of 1826, a Captain Sawyer, of the ship ''Harmony'', of

Hull Hull may refer to: Structures * Chassis, of an armored fighting vehicle * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a ship * Submarine hull Mathematics * Affine hull, in affi ...

, while cruising for northern bottlenose whales at 62° N and about 57° W, found the type specimen, floating at the surface, of what was named ''Ophiognathus ampullaceus'' by I. Harwood, at the time the professor of natural history at the

Royal Institution of Great Britain The Royal Institution of Great Britain (often the Royal Institution, Ri or RI) is an organisation for scientific education and research, based in the City of Westminster. It was founded in 1799 by the leading British scientists of the age, inc ...

. It was at first thought to be an inflated seal skin, but on getting closer they realized it was alive. It was attempting to eat a perch of "about seven inches in circumference". The specimen was captured and preserved in rum.

Physical characteristics

Like other

saccopharyngiforms The saccopharyngiformes are a derived lineage of unusual eels within the order Anguilliformes, and includes families Cyematidae, Monognathidae, Eurypharyngidae, Saccopharyngidae, and the proposed family Neocyematidae. Most of the fish in this gro ...

, these fish have large mouths and long, slender bodies with long tails that have a

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

organ at the tip. The function of this organ is currently unknown. ''Saccopharynx ampullaceus'' lacks a traditional gas-filled

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth w ...

, presumably due to the pressures at the depths they live in. Instead, the function of the swim bladder has been replaced by lymphatic spaces that run along the spine which are filled with a gelatinous substance. This gelatinous substance is thought to be maintained by the eel's aglomerular kidney.

References

Saccopharyngidae Fish of the North Atlantic Marine fauna of West Africa Fish described in 1827 {{Saccopharyngiformes-stub