A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom . Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans adapted to their marine environments, including most numerously fish , but also mammals such as cetaceans ( whales , dolphins , and porpoises ), and even extinct ancient marine reptiles such as various known species of ichthyosaurs . Most species have only one dorsal fin, but some have two or three.
16-461: Lebias Goldfuss, 1820 (invalid name) Micromugil Gulia, 1861 Aphanius , commonly referred to as Mediterranean killifish, is a genus of the order Cyprinodontiformes in the family Aphaniidae . They are found in fresh and brackish waters in the coastal plains of the Mediterranean region . There were formerly 39 recognized species in this genus. However, the family Aphaniidae
32-426: A simple way to identify a billfish species. For example, the white marlin has a dorsal fin with a curved front edge and is covered with black spots. The huge dorsal fin, or sail, of the sailfish is kept retracted most of the time. Sailfish raise them if they want to herd a school of small fish, and also after periods of high activity, presumably to cool down. A dorsal fin is classified as a medial , unpaired fin that
48-409: Is located on the midline of the backs of some aquatic vertebrates. In development of the embryo in teleost fish, the dorsal fin arises from sections of the skin that form a caudal fin fold. The larval development and formation of the skeleton that support the median fins in adults result in pterygiophores. The skeletal elements of the pterygiophore includes basals and radials. The basals are located at
64-621: The Atheriniformes and are occasionally included with them. A colloquial term for the order as a whole is toothcarps , though they are not actually close relatives of the true carps – the latter belong to the superorder Ostariophysi , while the toothcarps are Acanthopterygii . The families of Cyprinodontiformes can be informally divided into three groups based on reproductive strategy: viviparous and ovoviviparous (all species give live birth), and oviparous (all species are egg-laying). The live-bearing groups differ in whether
80-760: The Early Miocene of the Mediterranean and Caucasus regions. are Fossils of Aphanius are found in strata of the Pleistocene of Italy (age range: from 11.608 to 5.332 million years ago.). Cyprinodontiformes Aplocheiloidei Cyprinodontoidei Microcyprini Regan, 1909 Cyprinodontiformes / ˌ s ɪ p r ɪ n oʊ ˈ d ɒ n t ɪ f ɔːr m iː z / is an order of ray-finned fish , comprising mostly small, freshwater fish. Many popular aquarium fish, such as killifish and live-bearers , are included. They are closely related to
96-470: The spiny dogfish and the Port Jackson shark have spines in their dorsal fins which are capable of secreting venom. Billfish have prominent dorsal fins. Like tuna, mackerel and other scombroids, billfish streamline themselves by retracting their dorsal fins into a groove in their body when they swim. The shape, size, position and colour of the dorsal fin varies with the type of billfish, and can be
112-479: The American Flag Fish, is a renowned algae eater in the aquarium, in spite of belonging to an order of fishes that do not generally consume any plant material. In addition, killifish derive some of the carotenoids and other chemicals required to make their body pigments from pollen grains on the surface of and in the gut of insects they eat from the surface of the water; this can be simulated in culture by
128-454: The base of the dorsal fin, and are closest to the body. The radials extend outward from the body to support the rest of the fin. These elements serve as attachment sites for epaxial muscles. The muscles contract and pull against the basals of the pterygiophores along one side of the body, which helps the fish move through water by providing greater stability. In these types of fish, the fins are made of two main components. The first component
144-437: The distinctive nicks and wear patterns which develop on the dorsal fins of large cetaceans to identify individuals in the field. The bony or cartilaginous bones that support the base of the dorsal fin in fish are called pterygiophores . The main purpose of the dorsal fin is to stabilize the animal against rolling and to assist in sudden turns. Some species have further adapted their dorsal fins to other uses. The sunfish uses
160-459: The dorsal fin (and the anal fin ) for propulsion. In anglerfish , the anterior of the dorsal fin is modified into a biological equivalent to a fishing pole and a lure known as illicium or esca . Many catfish can lock the leading ray of the dorsal fin in an extended position to discourage predation or to wedge themselves into a crevice. Some animals have developed dorsal fins with protective functions, such as spines or venom. For example, both
176-419: The gut contents were invariably ants, others have reported insects, worms and aquatic crustaceans. Aquarium specimens are invariably seen eating protozoans from the water column and the surfaces of leaves, however these are not apparent as stomach contents. Many members of the family Cyprinodontidae (the pupfishes) eat plant material as well and some have adapted to a diet very high in algae to the point where one,
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#1732765051704192-466: The latter possibly twice. Some members of this order are notable for inhabiting extreme environments, such as saline or very warm waters, heavily polluted waters, rain water pools devoid of minerals and made acidic by decaying vegetation, or isolated situations where no other types of fish occur. They are typically carnivores , and often live near the surface, where the oxygen-rich water compensates for environmental disadvantages. Scheel (1968) observed
208-543: The least killifish ( Heterandria formosa ), is just 8 mm (0.31 in) long as an adult. CYPRINODONTIFORMES The family Aplocheilidae has been expanded by some authorities to include all the killifishes with three subfamilies, Aplocheilinae, Cynolebiinae and Nothobranchiinae, but this is not the classification adopted in the 5th Edition of Fishes of the World . Dorsal fin Wildlife biologists often use
224-472: The use of special color enhancing foods that contain these compounds. Although the Cyprinodontiformes are a diverse group, most species contained within are small to medium-sized fish, with small mouths, large eyes, a single dorsal fin , and a rounded caudal fin . The largest species is the cuatro ojos ( Anableps dowei ), which measures 34 cm (13 in) in length, while the smallest,
240-637: The young are carried to term within (ovoviviparous) or without (viviparous) an enclosing eggshell. Phylogenetically however, one of the two suborders – the Aplocheiloidei – contains oviparous species exclusively, as do two of the four superfamilies of the other suborder (the Cyprinodontoidea and Valencioidea of the Cyprinodontoidei ). Vivipary and ovovivipary have evolved independently from oviparous ancestors,
256-450: Was split in 2020, and species were reallocated to eight monophyletic genera. Several species were reallocated; to five resurrected genera ( Anatolichthys , Aphaniops , Kosswigichthys , Paraphanius , and Tellia ) and two new genera Esmaeilius and Apricaphanius . Following the split , there are two valid species: Fossils of extinct species, including A. crassicaudatus and A. yerevanicus , are known as far back as
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