Leptocephalus is the flat and transparent larva of the eel, marine eels, and other members of the superorder Elopomorpha. This is one of the most diverse groups of teleosts, containing 801 species in 4 orders, 24 families, and 156 genera. This group is thought to have arisen in the Cretaceous period over 140 million years ago.
The American eel is a facultative catadromous fish found on the eastern coast of North America. Freshwater eels are fish belonging to the elopomorph superorder, a group of phylogenetically ancient teleosts. The American eel has a slender, snake-like body that is covered with a mucus layer, which makes the eel appear to be naked and slimy despite the presence of minute scales. A long dorsal fin runs from the middle of the back and is continuous with a similar ventral fin. Pelvic fins are absent, and relatively small pectoral fins can be found near the midline, followed by the head and gill covers. Variations exist in coloration, from olive green, brown shading to greenish-yellow and light gray or white on the belly. Eels from clear water are often lighter than those from dark, tannic acid streams.
The eel is a long, thin bony fish of the order Anguilliformes. Because fishermen never caught anything they recognized as young eels, the life cycle of the eel was a mystery for a very long period of scientific history. Although more than 6500 publications mention eels, much of their life history remains an enigma.
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, bobtail eels, and gulper eels. Some can live deep in the ocean, well into the aphotic zone, approximately 500–1800 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.
Slimeheads, also known as roughies and redfish, are mostly small, exceptionally long-lived, deep-sea beryciform fish constituting the family Trachichthyidae. Found in temperate to tropical waters of the Atlantic, Indian, and Pacific Oceans, the family comprises about 50 species in eight genera. Slimeheads are named for the network of muciferous canals riddling their heads.
The pelican eel is a deep-sea eel rarely seen by humans, though it is occasionally caught in fishing nets. 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 of that of the pelican.
The snubnosed eel, Simenchelys parasitica, also known as the pug-nosed eel, slime eel, or snub-nose parasitic eel, is a species of deep-sea eel and the only member of its genus. Some authors classify it as the sole member of the subfamily Simenchelyinae of the family Synaphobranchidae, or cutthroat eels, while others place it in its own monotypic family, the Simenchelyidae. It is found in the Atlantic and Pacific Oceans, typically at a depth of 500–1,800 m (1,600–5,900 ft) near the bottom. Although typically a scavenger, it is better known for using its powerful jaws and teeth to burrow into larger fishes as a parasite.
Snipe eels are a family, Nemichthyidae, of eels that consists of nine species in three genera. They are pelagic fishes, found in every ocean, mostly at depths of 300–600 m but sometimes as deep as 4000 m. Depending on the species, adults may reach 1–2 m (39–79 in) in length, yet they weigh only 80-400 g. They are distinguished by their very slender jaws that separate toward the tips as the upper jaw curves upward. The jaws appear similar to the beak of the bird called the snipe. Snipe eels are oviparous, and the juveniles, called Leptocephali, do not resemble the adults but have oval, leaf-shaped and transparent bodies. Different species of snipe eel have different shapes, sizes and colors. The similarly named bobtail snipe eel is actually in a different family and represented by two species, the black Cyema atrum and the bright red Neocyema erythrosoma.
The bobtail snipe eels are two species of deep-sea eels in the family Cyematidae, one only in each of two genera. They are small elongate fishes, growing up to 16cm in length.
Leptocephalus is a genus that was used for species of larval eels, called leptocephali, that were thought to be new fish species, or whose adult eel species were not known. Leptocephali differ so much in appearance from their adults that the larvae and adults of eels are not easily matched, and when first discovered, leptocephali were thought to be a distinct type of fishes, but not eels. Because of this, the genus designation of Leptocephalus was used for a while for unidentified leptocephali even after it was known that these were the larvae of eels thus becoming a "wastebasket taxon", but this practice is no longer used. Examples of marine congrid larvae, found in the western Indian Ocean and the Red Sea that were named this way are listed below. Only two species in two families are currently treated as having any validity, though the validity of L. bellottii is strongly in doubt.
The European conger is a species of conger of the family Congridae. It is the largest eel in the world and native to the northeast Atlantic, including the Mediterranean Sea.
Mullus barbatus is a species of goatfish found in the Mediterranean Sea, Sea of Marmara, the Black Sea and the eastern North Atlantic Ocean, where its range extends from Scandinavia to Senegal. They are fished, mostly by trawling, with the flesh being well regarded. The International Union for Conservation of Nature has assessed their conservation status as being of "least concern".
An eel is a 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 most are predators.
Spectrunculus grandis is a species of Rhizopharyngia ray-finned fish in the cusk-eel family known by the common names pudgy cusk-eel and giant cusk-eel. It is one of two species in the formerly monotypic genus Spectrunculus, the other species, S. crassus, having been differentiated in 2008.
Juvenile fish go through various stages between birth and adulthood. They start as eggs which hatch into larvae. The larvae are not able to feed themselves, and carry a yolk-sac which provides their nutrition. Before the yolk-sac completely disappears, the tiny fish must become capable of feeding themselves. When they have developed to the point where they are capable of feeding themselves, the fish are called fry. When, in addition, they have developed scales and working fins, the transition to a juvenile fish is complete and it is called a fingerling. Fingerlings are typically about the size of fingers. The juvenile stage lasts until the fish is fully grown, sexually mature and interacting with other adult fish.
The coffinfish is a species of sea toad of the family Chaunacidae, which consists of 17 species. It is found in salty temperate waters of southwestern Pacific, off east coast of Australia. The coffinfish was first discovered around February 1997 in Sicily, Italy by the skipper of the Libra, which was a trawler who was harbored in Mazara at the time. It can be also found in depths of 164–984.3 ft (50.0–300.0 m). Deep sea crab fishermen off the east coast of Florida pull them up from depth ranging from 5,000-8,000 feet about 54–68 miles off the coast. They have a globose and spiny body that grows to a maximum length of 22.0 cm (8.7 in) and a black mouth lining and an illicium on the snout that can be lowered into a groove.
The Southern snipe eel is an eel in the family Nemichthyidae. It was described by Charles Tate Regan in 1916, originally under the genus Leptocephalus. It is a marine, deep water-dwelling eel which is known from throughout the southern regions of the ocean, with the exception of the eastern Pacific. It is known to dwell at a maximum depth of 2,000 metres (6,600 ft). Males can reach a maximum total length of 77 centimetres (30 in).
Synaphobranchus dolichorhynchus is an eel in the family Synaphobranchidae. It was described by Einar Hagbart Martin Lea in 1913, originally under the genus Leptocephalus. It is a marine, subtropical eel which is known solely from larval specimens discovered in the northern Atlantic Ocean. It is known to dwell at a depth range of 100 to 150 metres.
Gerres nigri, the Guinean striped mojarra is a species of mojarra native to the eastern Atlantic Ocean. It inhabits estuaries, coastal waters and lagoons. This species can reach a maximum length of 20 cm (8 in), with 15 cm (6 in) being a more common size.
The Neocyematidae are a proposed family of fishes. This family, established from five described adult specimens of the species Neocyema erythrosoma, was originally thought to be a part of the family Cyematidae, until genomic sequencing in 2018 refuted this relationship.
