Actinopterygii, members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia, as opposed to the bulkier, fleshy lobed fins of the sister class Sarcopterygii. Resembling folding fans, the actinopterygian fins can easily change shape and wetted area, providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation between these fins and the internal skeleton.
Osteichthyes, also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes and the extinct placoderms and acanthodians, which have endoskeletons primarily composed of cartilage. The vast majority of extant fish are members of Osteichthyes, being an extremely diverse and abundant group consisting of 45 orders, over 435 families and 28,000 species. It is the largest class of vertebrates in existence today, encompassing most aquatic vertebrates, as well as all semi-aquatic and terrestrial vertebrates.
Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.
Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep-sea fishes include the flashlight fish, cookiecutter shark, bristlemouths, anglerfish, viperfish, and some species of eelpout.
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.
Neopterygii is a subclass of ray-finned fish (Actinopterygii). Neopterygii includes the Holostei and the Teleostei, of which the latter comprise the vast majority of extant fishes, and over half of all living vertebrate species. While living holosteans include only freshwater taxa, teleosts are diverse in both freshwater and marine environments. Many new species of teleosts are scientifically described each year.
The Osmeriformes are an order of ray-finned fish that includes the true or freshwater smelts and allies, such as the galaxiids and noodlefishes; they are also collectively called osmeriforms. They belong to the teleost superorder Protacanthopterygii, which also includes pike and salmon, among others. The order's name means "smelt-shaped", from Osmerus + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek osmé + Latin forma, the former in reference to the characteristic aroma of the flesh of Osmerus.
Caproidae, or boarfishes, are a small family of marine fishes comprising two genera and 19 species. These fishes are found throughout the world in temperate and tropical seas.
Slickheads, also known as nakedheads or smoothheads, are deep water fishes that belong to the family Alepocephalidae. They are most commonly found in the bathypelagic layer, which is approximately 3000m below the surface. They get their name from the lack of scales on their heads. Similarly, the scientific name is from the Greek ᾰ̓- (a-, "not"); λέπος (lepos, "scale"); and κεφαλή (kephalē, "head"). It has about 22 genera with ca. 96 species.
The Syngnathiformes are an order of ray-finned fishes that includes the leafy seadragons, sea moths, trumpetfishes and seahorses, among others.
The Microcanthinae, commonly known as footballers, mados, stripeys, and moonlighters, are a subfamily of the sea chubs, a family of marine ray-finned fish in the order Perciformes.
The Argentiniformes is an order of marine ray-finned fish whose distinctness was recognized only fairly recently. In former times, they were included in the Osmeriformes as suborder Argentinoidei. That term refers only to the suborder of marine smelts and barreleyes in the classification used here, with the slickheads and allies being the Alepocephaloidei. These suborders were treated as superfamilies Argentinoidea and Alepocephaloidea, respectively, when the present group was still included in the Osmeriformes.
Bathyprion, is a genus of deepwater marine ray-finned fish belonging to the family Alepocephalidae, the slickheads. Its only extant species is Bathyprion danae, the fangtooth smooth-head. This species is found in the Atlantic and western Pacific Oceans.
Narcetes is a genus of slickheads. It was formally described by Alfred William Alcock in 1890. It currently contains six described species.
Edward Orlando Wiley III is the curator emeritus of ichthyology at the University of Kansas Biodiversity Institute and professor of systematics and evolution for the Department of Ecology and Evolutionary Biology at the University of Kansas. His master's adviser was Darrell Hall, of Sam Houston State University (retired), and his doctoral advisor was Donn E. Rosen, of the American Museum of Natural History (deceased). Wiley has published extensively in topics related to phylogenetic systematics, is a Past President of the Society of Systematic Biology and was involved in the founding of the Willi Hennig Society. Wiley is known for building on and establishing conceptual advances in the evolutionary species concept, first formulated by George Gaylord Simpson. Wiley defines an evolutionary species as:
Percomorpha is a large clade of ray-finned fish with more than 17 000 known species that includes the tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish.
The Neoteleostei is a large clade of bony fish mostly consisting of marine clades. Only three lineages have freshwater species: Percopsiformes (Troutperches), which lives exclusively in freshwater, Gadiformes (cods), which is largely marine except from burbot that live in freshwater and a few populations of cod in brackish water, and the Percomorpha, which in addition to several marine groups also have many freshwater forms.
Otocephala is a clade of ray-finned fishes within the infraclass Teleostei that evolved some 230 million years ago. It is named for the presence of a hearing (otophysic) link from the swimbladder to the inner ear. Other names proposed for the group include Ostarioclupeomorpha and Otomorpha.
The phylogenetic classification of bony fishes is a phylogenetic classification of bony fishes and is based on phylogenies inferred using molecular and genomic data for nearly 2000 fishes. The first version was published in 2013 and resolved 66 orders. The latest version was published in 2017 and recognised 72 orders and 79 suborders.
Narcetes shonanmaruae, the yokozuna slickhead, is a species of large marine ray-finned fish, a slickhead belonging to the family Alepocephalidae. At over 2.5 metres (8.2 ft) in length, it is the largest species of slickhead, and the largest species of bony fish entirely restricted to the deep ocean.
