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 group are deep-dwelling and rarely seen, typically known from only a handful of specimens. Species include recognizable fish such as pelican eels and bobtail eels. Some can live deep in the ocean, well into the aphotic zone, approximately 500 to 1,800 meters deep. Extensive research has not been conducted on them due to being indirectly observed, with some species known only from their larvae. All families except for the exceptionally rare individuals of proposed family Neoceymatidae are found in all major oceans.
The pelican eel is a deep-sea eel. It is the only known member of the genus Eurypharynx and the family Eurypharyngidae. It belongs to the "saccopharyngiforms", members of which were historically placed in their own order, but are now considered true eels in the order Anguilliformes. The pelican eel has been described by many synonyms, yet nobody has been able to demonstrate that more than one species of pelican eel exists. It is also referred to as the gulper eel, pelican gulper, and umbrella-mouth gulper. The specific epithet pelecanoides refers to the pelican, as the fish's large mouth is reminiscent to that of the pelican.
Ophichthidae is a family of fish in the order Anguilliformes, commonly known as the snake eels. The term "Ophichthidae" comes from Greek ophis ("serpent") and ichthys ("fish"). Snake eels are also burrowing eels. They are named for their physical appearance, as they have long, cylindrical, snake-like bodies. This family is found worldwide in tropical to warm temperate waters. They inhabit a wide range of habitats, from coastal shallows and even rivers, to depths below 800 m (2,600 ft). Most species are bottom dwellers, hiding in mud or sand to capture their prey of crustaceans and small fish, but some are pelagic.
The superorder Elopomorpha contains a variety of types of fishes that range from typical silvery-colored species, such as the tarpons and ladyfishes of the Elopiformes and the bonefishes of the Albuliformes, to the long and slender, smooth-bodied eels of the Anguilliformes. The one characteristic uniting this group of fishes is they all have leptocephalus larvae, which are unique to the Elopomorpha. No other fishes have this type of larvae.
Monognathus, or onejaw, is the only genus of the family Monognathidae of deep-sea eels. The name comes from the Greek monos meaning “one” and gnathos meaning “jaw”, a reference to the large mouth in comparison with the rest of the fish, and also the absence of an upper jaw.
Gymnothorax is a genus of fish in the family Muraenidae found in Atlantic, Indian and Pacific Ocean. With more than 120 species, it the most speciose genus of moray eels.
Eels are ray-finned fish belonging to the order Anguilliformes, which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage and are usually predators.
Scuticaria okinawae is a moray eel found in the Pacific and Indian Oceans. It is commonly known as the shorttailed snake moray, shorttail moray, Seale's moray eel, or the Bennett's moray.
Dysomma is a genus of eels in the cutthroat eel family Synaphobranchidae.
Ophidion is a genus of cusk-eels.
Otophidium is a genus of cusk-eels, part of the subfamily Ophidiinae in the family Ophidiidae. They are found in the western Atlantic and eastern Pacific.
The tropical conger, also known as the Scheele's conger, is an eel in the family Congridae. It was described by Pehr Hugo Strömman in 1896, originally under the genus Leptocephalus. It is a tropical, marine eel which is known from the Indo-Pacific, including Natal and Mozambique. It inhabits reefs in lagoons, and is known to dwell at a depth of 9 metres. Males can reach a maximum total length of 20 centimetres (7.9 in).
Ariosoma sereti is an eel in the family Congridae. It was described by Emma Stanislavovna Karmovskaya in 2004. It is a marine, deep water-dwelling eel which is known from the Marquesas Islands, in the eastern central Pacific Ocean. It is known to dwell at a depth range of 95–370 metres. Females can reach a maximum total length of 26.5 centimetres.
The Bullish conger is an eel in the family Congridae. It was described by David G. Smith and Robert H. Kanazawa in 1977, originally under the genus Rhechias. It is a marine, deep water-dwelling eel which is known from the Gulf of Mexico to the Amazon, in the western Atlantic Ocean. It dwells at a depth range of 366–475 meters. Males can reach a maximum total length of 39.5 centimeters.
Gnathophis grahami, or Graham's conger, is an eel in the family Congridae. It was described by Emma Stanislavovna Karmovskaya and John Richard Paxton in 2000. It is a subtropical, marine eel which is known from New South Wales, Australia, in the southwestern Pacific Ocean. It dwells at a depth range of 50–350 metres.
Gorgasia naeocepaea, the freckled garden eel, is an eel in the family Congridae. It was described by James Erwin Böhlke in 1951, originally under the genus Taenioconger. It is a marine, tropical eel which is known from the western central Pacific Ocean, including the Philippines and Indonesia. It is known to inhabit sandy regions, and dwells at a depth range of 10 to 24 metres. Males can reach a maximum total length of 75 centimetres (30 in).
Saccopharynx ampullaceus, referred to as the gulper eel, gulper, taillight gulper or pelican-fish, is an ocean-dwelling eel found in the North Atlantic Ocean. They are found up to a depth of 3,000 m (9,800 ft). These fish are rarely observed, so little information is currently known about their habits or full distribution.
Monognathus boehlkei is a deep-sea eel inhabiting all oceans at depths up to 2,000 meters. Little is known of this species.
Saccopharynx lavenbergi is a species of gulper eel, also known as the whiptail gulper. This fish is known for its large mouth and long whiplike tail. This species is not commonly found in the wild, with fewer than twenty sightings over 30 years of ROV operation by MBARI. Even though it has rarely been sighted, this gulper eel was chosen to be the logo for MBARI.
Saccopharynx berteli is a species of ray-finned fish within the family Saccopharyngidae. It is known from a single holotype collected from the central Pacific Ocean through an open fishing net at a depth of 1100 meters in 1977. The individual caught was an immature male with a length of 89.5 centimeters. It has been classified as a 'Data deficient' species by the IUCN Red List as there is little information regarding its population, ecology, distribution, and potential threats.
