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.
The mackerel, tuna, and bonito family, Scombridae, includes many of the most important and familiar food fishes. The family consists of 51 species in 15 genera and two subfamilies. All species are in the subfamily Scombrinae, except the butterfly kingfish, which is the sole member of subfamily Gasterochismatinae.
The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents. These birds are adapted for swimming, floating on the water surface, and in some cases diving in at least shallow water. The family contains around 174 species in 43 genera.
Chanidae is a family of fishes which has a number of fossil genera and one monotypic extant genus which contains the milkfish.
The crocodylian family Crocodylidae includes the crocodiles, which are the members of the subfamily Crocodylinae, as well as potentially the false gharial, the only extant species of the subfamily Tomistominae. The latter is a subject of controversy as to whether it is a crocodile or actually belongs in the family Gavialidae. Further genetic analysis has to be done to come to a final conclusion.
The Geoemydidae are one of the largest and most diverse families in the order Testudines (turtles), with about 70 species. The family includes the Eurasian pond and river turtles and Neotropical wood turtles.
Grenadiers or rattails are generally large, brown to black gadiform marine fish of the subfamily Macrourinae, the largest subfamily of the family Macrouridae. Found at great depths from the Arctic to Antarctic, members of this subfamily are amongst the most abundant of the deep-sea fish.
Macroudidae is a family of deep sea fish, a diverse and ecologically important group, which are part of the order of cod-like fish, the Gadiformes. The species in the Macrouridae are characterised by their large heads which normally have a single barbel on the chin, projecting snouts, and slender bodies that taper to whip-like tails, without an obvious caudal fin but what there is of the caudal fin is often confluent with the posterior dorsal and anal fins. There are normally two dorsal fins, the anterior dorsal fin is quite high, the posterior quite low but is longer and takes up a greater proportion of the fish's of the back, species in the subfamily Macrouroidinae have a single dorsal fin. The long anal fin is almost as long as the second dorsal fin is nearly as long as the posterior dorsal, and sometimes it is longer. The pelvic fin is inserted in the vicinity of the thorax and normally has 5-17 fin rays but are absent in Macrouroides. The body is covered in small scales and if they have a photophore, it is usually on the midline of the abdomen just in front of the anus. The bioluminescence of these fish is produced by symbiotic bioluminescent bacteria. The structure of the skull has been used to show their placing in the Gadiformes, but they differ from the typical cods in that they possess one stout spine in the anterior dorsal fin.
The marine hatchetfishes or deep-sea hatchetfishes as well as the related bottlelights, pearlsides and constellationfishes are small deep-sea ray-finned fish of the stomiiform family Sternoptychidae. They are not closely related to and should not be confused with the freshwater hatchetfishes, which are teleosts in the characiform family Gasteropelecidae. The Sternoptychidae have 10 genera and about 70 species altogether.
Pleuronectidae, also known as righteye flounders, are a family of flounders. They are called "righteye flounders" because most species lie on the sea bottom on their left sides, with both eyes on their right sides. The Paralichthyidae are the opposite, with their eyes on the left side. A small number of species in Pleuronectidae can also have their eyes on the left side, notably the members of the genus Platichthys.
The Old World silversides are a family, Atherinidae, of fish in the order Atheriniformes. They occur worldwide in tropical and temperate waters. About two-thirds of the species are marine, and the remainder live in fresh water. The 74 species are in 13 genera. The genus Craterocephalus is the most diverse with 25 species. Four genera are monotypic.
The Ceratophryidae, also known as common horned frogs, are a family of frogs found in South America. It is a relatively small family with three extant genera and 12 species. However, fossils of the giant Beelzebufo from Cretaceous Madagascar suggest the taxon may have once ranged throughout the prehistoric supercontinent of Gondwana.
The bitterling-like cyprinids form the cyprinid subfamily Acheilognathinae. This subfamily contains four genera, although the Khanka spiny bitterling is often placed in Acheilognathus, and at least 71 described species to date. Over half of the species are in the genus Acheilognathus.
The Samaridae are a family, the crested flounders, of small flatfishes native to the Indo-Pacific. They were formerly classified as a subfamily of Pleuronectidae. The family contains four genera with a total of almost 30 species.
The roughscale sole, Clidoderma asperrimum, is an edible flatfish of the family Pleuronectidae. It is a demersal fish that lives on sandy, muddy bottoms at depths from 15 to 1,900 metres, though it is most commonly found at depths of between 400 and 600 metres. It can reach 62 centimetres (24 in) in length and can weigh up to 4.4 kilograms (9.7 lb). Its native habitat is the northern Pacific, from the coasts of China and Japan, across the Bering Sea to Alaska, Canada and the Californian coast of America.
The Poecilopsettidae are a family of flatfish in the order Pleuronectiformes, comprising three genera and 21 species. Species are typically demersal, living on marine bottoms at depths between 60 and 500 m in the Indo-Pacific and northwestern Atlantic; the deepest recorded occurrence is 1,636 m (5,367 ft) in the deepwater dab, Poecilopsetta beanii. Sizes range from 9 to 19 cm in length, though most species are usually under 15 cm (5.9 in) long. Diets consist of zoobenthos.
Rhombosoleidae is a family of flatfish in the order Pleuronectiformes, comprising nine genera and 19 species; all members of this family are right eye flounders with asymmetrical pelvic fins. Species are typically demersal, living on bottoms in temperate marine waters on the continental shelf, although some species of Rhombosolea enter fresh water in New Zealand. Most are restricted to waters around Australia and New Zealand, though the Remo flounder, Oncopterus darwinii, occurs in the southwestern Atlantic and the Indonesian ocellated flounder, Psammodiscus ocellatus, occurs in Indonesia.
Schizaeaceae is a family of ferns in the order Schizaeales. In the Pteridophyte Phylogeny Group classification of 2016, it includes only two genera. Alternatively, two families kept separate in PPG I, Lygodiaceae and Anemiaceae, may be included in Schizaeaceae so that the family has four genera. In this approach, the Schizaeaceae of PPG I is treated as the subfamily Schizaeoideae.
The Cultrinae are one of at least 13 subfamilies of cyprinid fish. It contains ten genera.
Atherinomorinae is a subfamily of silversides from the family, Atherinidae, the Old World silversides.
