The ray-finned fishes are so called because their fins are webs of skin supported by bony or horny spines ("rays"), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii (lobe-finned fish). These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles).
Numerically, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm (0.3 in), to the massive ocean sunfish, at 2,300 kg (5,070 lb), and the long-bodied oarfish, at 11 m (36 ft).
Temporal range: Late Silurian - recent
Ray-finned fishes occur in many variant forms. The main features of a typical ray-finned fish are shown in the adjacent diagram.
Ray finned fishes have many different types of scales, but all higher order actinopterygii (teleosts) have Leptoid scales. The outer part of these scales fan out with bony ridges while the inner part is crossed with fibrous connective tissue. Leptoid scales are thinner and more transparent than other types of scales, and lack the hardened enamel or dentine like layers found in many other fish. Unlike ganoid scales which are found in non teleost actinopterygii, further scales are added in concentric layers as the fish grows.
Ray-finned fish are very varied in size and shape, and in the number of their ray-fins and the manner in which they arrange them.
In nearly all ray-finned fish, the sexes are separate, and in most species the females spawn eggs that are fertilized externally, typically with the male inseminating the eggs after they are laid. Development then proceeds with a free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism. In most cases this involves protogyny, fish starting life as females and converting to males at some stage, triggered by some internal or external factor. Protandry, where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization. Of the oviparous teleosts, most (79%) do not provide parental care. Viviparity, ovoviviparity, or some form of parental care for eggs, whether by the male, the female, or both parents is seen in a significant fraction (21%) of the 422 teleost families; no care is likely the ancestral condition. Viviparity is relatively rare and is found in about 6% of teleost species; male care is far more common than female care. Male territoriality "preadapts" a species for evolving male parental care.
There are a few examples of fish that self-fertilise. The mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to the fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below 19 °C (66 °F) and can fertilise eggs that are then spawned by the female. This maintains genetic variability in a species that is otherwise highly inbred.
Actinopterygians are divided into the subclasses Chondrostei and Neopterygii. The Neopterygii, in turn, are divided into the infraclasses Holostei and Teleostei. During the Mesozoic and Cenozoic the teleosts in particular diversified widely, and as a result, 96% of all known fish species are teleosts. The cladogram shows the major groups of actinopterygians and their relationship to the terrestrial vertebrates (tetrapods) that evolved from a related group of fish. Approximate dates are from Near et al., 2012.
The polypterids (bichirs and ropefish) are the sister lineage of all other actinopterygians, the Acipenseriformes (sturgeons and paddlefishes) are the sister lineage of Neopterygii, and Holostei (bowfin and gars) are the sister lineage of teleosts. The Elopomorpha (eels and tarpons) appears to be the most basic teleosts.
|Chondrostei||Chondrostei (cartilage bone) are primarily cartilaginous fish showing some ossification. Earlier definition of Chondrostei is now known to be paraphyletic meaning that this subclass does not contain all the descendants of their common ancestor. There were 52 species divided among two orders, the Acipenseriformes (sturgeons and paddlefishes) and the Polypteriformes (reedfishes and bichirs). Reedfish and birchirs are now separated from the Chondrostei into their own sister lineage, the Cladistia. It is thought that the chondrosteans evolved from bony fish but lost the bony hardening of their cartilaginous skeletons, resulting in a lightening of the frame. Elderly chondrosteans show beginnings of ossification of the skeleton, suggesting that this process is delayed rather than lost in these fish. This group had once been classified with the sharks: the similarities are obvious, as not only do the chondrosteans mostly lack bone, but the structure of the jaw is more akin to that of sharks than other bony fish, and both lack scales (excluding the Polypteriforms). Additional shared features include spiracles and, in sturgeons, a heterocercal tail (the vertebrae extend into the larger lobe of the caudal fin). However the fossil record suggests that these fish have more in common with the Teleostei than their external appearance might suggest.|
|Neopterygii||Neopterygii (new fins) appeared somewhere in the Late Permian, before the time of the dinosaurs. There are only few changes during their evolution from the earlier actinopterygians. They are a very successful group of fishes, because they can move more rapidly than their ancestors. Their scales and skeletons began to lighten during their evolution, and their jaws became more powerful and efficient. While electroreception and the ampullae of Lorenzini is present in all other groups of fish, with the exception of hagfish, Neopterygii has lost this sense, though it later re-evolved within Gymnotiformes and catfishes, who possess nonhomologous teleost ampullae.|
Acanthopterygii (meaning "spiny finned one") is a superorder of bony fishes in the class Actinopterygii. Members of this superorder are sometimes called ray-finned fishes for the characteristic sharp, bony rays in their fins; however this name is often given to the class Actinopterygii as a whole.Caesioperca
Caesioperca is a genus of ray-finned fish in the sub-family Anthiadinae in the sea bass family Serranidae. It contains just two species, found in the ocean off Southern Australia and New Zealand.Caprodon
Caprodon is a small genus of fish belonging to the subfamily Anthiadinae. It contains three species.Cichliformes
Cichliformes is an order of fishes, previously classifies under the order Perciformes but now many authorities consider it to be an order within the subseries Ovalentaria.Euteleostomi
Euteleostomi is a successful clade that includes more than 90% of the living species of vertebrates. Euteleostomes are also known as "bony vertebrates". Both its major subgroups are successful today: Actinopterygii includes the majority of extant fish species, and Sarcopterygii includes the tetrapods.
"Osteichthyes" in the paleontological sense (i.e., "bony vertebrates"), is synonymous with Euteleostomi. However, in ichthyology and Linnaean taxonomy Osteichthyes, literally "bony fish," refers to the paraphyletic group that differs by excluding tetrapods. The name Euteleostomi, coined as a monophyletic alternative that unambiguously includes the living tetrapods, is more widely used in bioinformatics and related fields. The term Euteleostomi comes from Eu-teleostomi, where "Eu-" comes from the Greek εὖ meaning well or good, so the clade can be defined as the living teleostomes.
Euteleostomes originally all had endochondral bone, fins with lepidotrichs (fin rays), jaws lined by maxillary, premaxillary, and dentary bones composed of dermal bone, and lungs. Many of these characters have since been lost by descendant groups, however, such as lepidotrichs lost in tetrapods, and bone lost among the chondrostean fishes. Lungs have been retained in dipnoi (lungfish), and many tetrapods (birds, mammals, reptiles, and some amphibians). In many ray-finned fishes lungs have evolved into swim bladders for regulating buoyancy, while in others they continue to be used as respiratory gas bladders.Flying fish
The Exocoetidae are a family of marine fish in the order Beloniformes class Actinopterygii, known colloquially as flying fish. About 64 species are grouped in seven to nine genera. While they cannot fly in the same way as a bird does, flying fish can make powerful, self-propelled leaps out of water where their long wing-like fins enable gliding for considerable distances above the water's surface. The Exocet missile is named after them, as variants are launched from underwater, and take a low trajectory, skimming the surface, before striking their targets.
The oldest known fossil of a flying or gliding fish, Potanichthys xingyiensis, dates back to the Middle Triassic, 235–242 million years ago. However, this fossil is not related to modern flying fish, which evolved independently about 66 million years ago.Kurtiformes
The Kurtiformes consist of two extant families of ray-finned fish, the Indo-Pacific Kurtidae, the nursery fish, with two species and the much more diverse and widespread Apogonidae, the cardinalfishes, the order is part of the Percomorpha clade and is regarded by many authorities as a sister taxon to the Gobiiformes.Lepidoperca
Lepidoperca is a small genus of fish belonging to the Anthiadinae subfamily. It includes ten species.List of Lessepsian migrant species
Lessepsian migrants, named after Ferdinand de Lesseps, the French engineer in charge of the Suez Canal's construction, are marine species that are native to the waters on one side of the Suez Canal, and which have been introduced by passage through the canal to the waters on its other side, giving rise to new colonies there and often becoming invasive.
Most Lessepsian migrations are of Red Sea species invading the Mediterranean Sea; few occur in the opposite direction.List of chordate orders
This page contains a list of all of the classes and orders that are located in the Phylum Chordata.Neopterygii
Neopterygii are a group of fish. Neopterygii means "new fins" (from Greek νέος neos, new, and πτέρυξ pteryx, fin). Only a few changes occurred during their evolution from the earlier actinopterygians. They appeared sometime in the Late Permian, before the time of the dinosaurs. The Neopterygii were a very successful group of fish, because they could move more rapidly than their ancestors. Their scales and skeletons began to lighten during their evolution, and their jaws became more powerful and efficient. While electroreception and the ampullae of Lorenzini are present in all other groups of fish, with the exception of hagfish (although hagfish are not Actinopterygii, they are Agnathans), Neopterygii have lost this sense, even if it has later been re-evolved within Gymnotiformes and catfishes, which possess nonhomologous teleost ampullae.Osteichthyes
Osteichthyes (), popularly referred to as the bony fish, is a diverse taxonomic group of fish that have skeletons primarily composed of bone tissue, as opposed to cartilage. The vast majority of fish are members of Osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, and over 435 families and 28,000 species. It is the largest class of vertebrates in existence today.
The group Osteichthyes is divided into the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The oldest known fossils of bony fish are about 420 million years old, which are also transitional fossils, showing a tooth pattern that is in between the tooth rows of sharks and bony fishes.Osteichthyes can be compared to Euteleostomi. In paleontology, the terms are synonymous. In ichthyology, the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tetrapods that evolved from lobe-finned fish, whereas prior to 2014 the view of most ichthyologists was that Osteichthyes includes only fishes, and were therefore paraphyletic. However, in 2014, an ichthyology paper was published with phylogenetic trees that treat the Osteichthyes as a clade including tetrapods.Palaeonisciformes
The Palaeonisciformes are an extinct order of early ray-finned fishes (Actinopterygii) which began in the Late Silurian and ended in the Late Cretaceous. The name of the order is derived from the Greek words paleo (ancient) and ὀνίσκος (oniskos or woodlouse), probably pertaining to the organization of the fishes' scales, similar to the exoskeletal plating of woodlice.Paracanthopterygii
Paracanthopterygii is a superorder of fishes. Members of this group are called paracanthopterygians.
It includes five orders:
Percopsiformes (trout-perches & allies)
Gadiformes (cods & allies)Percomorpha
The Percomorpha is a large clade of bony fish that includes the tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish.Sturgeon
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. Their evolution dates back to the Triassic some 245 to 208 million years ago. The family is grouped into four genera: Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. Four species may now be extinct. Two closely related species, Polyodon spathula (American paddlefish) and Psephurus gladius (Chinese paddlefish, possibly extinct) are of the same order, Acipenseriformes, but are in the family Polyodontidae and are not considered to be "true" sturgeons. Both sturgeons and paddlefish have been referred to as "primitive fishes" because their morphological characteristics have remained relatively unchanged since the earliest fossil record. Sturgeons are native to subtropical, temperate and sub-Arctic rivers, lakes and coastlines of Eurasia and North America.Sturgeons are long-lived, late-maturing fishes with distinctive characteristics, such as a heterocercal caudal fin similar to those of sharks, and an elongated, spindle-like body that is smooth-skinned, scaleless, and armored with five lateral rows of bony plates called scutes. Several species can grow quite large, typically ranging 7–12 ft (2-3½ m) in length. The largest sturgeon on record was a beluga female captured in the Volga estuary in 1827, weighing 1,571 kg (3,463 lb) and 7.2 m (24 ft) long. Most sturgeons are anadromous bottom-feeders, which migrate upstream to spawn, but spend most of their lives feeding in river deltas and estuaries. Some species inhabit freshwater environments exclusively, while others primarily inhabit marine environments near coastal areas, and are known to venture into open ocean.
Several species of sturgeon are harvested for their roe, which is processed into the luxury food caviar. This has led to serious overexploitation, which combined with other conservation threats, has brought most of the species to critically endangered status, at the edge of extinction.Teleostomi
Teleostomi is an obsolete clade of jawed vertebrates that supposedly includes the tetrapods, bony fish, and the wholly extinct acanthodian fish. Key characters of this group include an operculum and a single pair of respiratory openings, features which were lost or modified in some later representatives. The teleostomes include all jawed vertebrates except the chondrichthyans and the extinct class Placodermi.
Recent studies indicate that Osteichthyes evolved from placoderms like Entelognathus, while acanthodians are more closely related to modern chondrichthyes. Teleostomi, therefore, is not a valid, natural clade, but a polyphyletic group of species.The clade Teleostomi should not be confused with the similar-sounding fish clade Teleostei.Zaniolepis
Zaniolepis is a genus of scorpaeniform fish native to the eastern Pacific Ocean. Z. frenata is known to have been a source of food to the Native American inhabitants of San Nicolas Island off the coast of southern California, United States during the Middle Holocene.
Extant Actinopterygii orders by subclass
Extant chordate classes