A flatfish is a member of the ray-finned demersal fish order Pleuronectiformes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through or around the head during development. Some species face their left sides upward, some face their right sides upward, and others face either side upward.
Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton. Lungfish represent the closest living relatives of the tetrapods. The mouths of lungfish typically bear tooth plates, which are used to crush hard shelled organisms.
The frilled shark, also known as the lizard shark, is one of the two extant species of shark in the family Chlamydoselachidae. The frilled shark is considered a living fossil, because of its primitive, anguilliform (eel-like) physical traits, such as a dark-brown color, amphistyly, and a 2.0 m (6.6 ft)–long body, which has dorsal, pelvic, and anal fins located towards the tail. The common name, frilled shark, derives from the fringed appearance of the six pairs of gill slits at the shark's throat.
Ophidiiformes is an order of ray-finned fish that includes the cusk-eels, pearlfishes, viviparous brotulas, and others. Members of this order have small heads and long slender bodies. They have either smooth scales or no scales, a long dorsal fin and an anal fin that typically runs into the caudal fin. They mostly come from the tropics and subtropics, and live in both freshwater and marine habitats, including abyssal depths. They have adopted a range of feeding methods and lifestyles, including parasitism. The majority are egg-laying, but some are viviparous.
Synbranchiformes, often called swamp eels, though that name can also refer specifically to Synbranchidae, is an order of ray-finned fishes that are eel-like but have spiny rays, indicating that they belong to the superorder Acanthopterygii.
Latimeria is a rare genus of fish which contains the two only living species of coelacanth. It includes two extant species: the West Indian Ocean coelacanth and the Indonesian coelacanth. They follow the oldest known living lineage of Sarcopterygii, which means they are more closely related to lungfish and tetrapods than to the common ray-finned fishes and cartilaginous fishes.
The Anguillidae are a family of ray-finned fish that contains the freshwater eels. Except from the genus Neoanguilla, with the only known species Neoanguilla nepalensis from Nepal, all the extant species and six subspecies in this family are in the genus Anguilla, and are elongated fish of snake-like bodies, with long dorsal, caudal and anal fins forming a continuous fringe. They are catadromous, spending their adult lives in freshwater, but migrating to the ocean to spawn.
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.
The cusk-eel family, Ophidiidae, is a group of marine bony fishes in the Ophidiiformes order. The scientific name is from the Greek ophis meaning "snake", and refers to their eel-like appearance. True eels diverged from other ray-finned fish during the Jurassic, while cusk-eels are part of the Percomorpha clade, along with tuna, perch, seahorses and others.
The speckled moray eel is a moray eel found in the eastern Pacific Ocean, around the Galapagos Islands and along the Central American coast from Costa Rica to Colombia. It is also found in the Gulf of California. It reaches a length of about 170 cm.
The Kidako moray is a species of marine fish in the family Muraenidae. It inhabits coral reefs or lagoons and could be found in tropical and subtropical seas near Taiwan, Japan, and Australia. The species is diurnal, which means it is more active in the daytime than the nighttime. It is also piscivorous: it consumes fish, octopus, and squid. Other than the Kidako moray, there are about 200 species of moray eels in the Muraenidae family. The Kidako moray doesn't attack humans unless they are provoked. However, due to the menacing looks of the Kidako moray and moray eels in general, they are feared by divers and snorkelers.
The wolf eel is a species of marine ray-finned fish belonging to the family Anarhichadidae, the wolf fishes. It is found in the North Pacific Ocean. Despite its common name and resemblance, it is not a true eel. It is the only species in the monotypic genus Anarrhichthys.
Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish, and hypogean fish.
Eels are ray-finned fish belonging to the order Anguilliformes, which consists of eight suborders, 20 families, 164 genera, and about 1000 species. Eels undergo considerable development from the early larval stage to the eventual adult stage and are usually predators.
Anguillavus is an extinct genus of basal marine eel that lived during the upper Cenomanian of Lebanon. It is the only known member of the family Anguillavidae. Its primitive nature compared to extant eels is indicated by it still retaining its pelvic fins, which have been lost in modern eels.
Echidna peli is a moray eel found in the eastern Atlantic Ocean. It was first named by Johann Jakob Kaup in 1856, and is commonly known as the pebbletooth moray.
Panturichthys fowleri, commonly known as Fowler's shortfaced eel, is an eel in the family Heterenchelyidae. It was described by Adam Ben-Tuvia in 1953, originally under the genus Lophenchelys. It is a subtropical, marine eel which is known from a single specimen collected from Israel, in the Mediterranean Sea. The holotype specimen was discovered dwelling at a depth range of 27–55 metres.
Bathycongrus aequoreus is an eel in the family Congridae. It was described by Charles Henry Gilbert and Frank Cramer in 1897, originally under the genus Congermuraena. It is a marine, deep water-dwelling eel which is known from Hawaii, in the eastern central Pacific Ocean. It dwells at a depth range of 300–686 metres, prefers deeper water and leads a benthic lifestyle.
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.
Gymnothorax elaineheemstrae is a fish in the family Muraenidae.
