Dorsal fin

Dorsal fin

Overview
A dorsal fin is a fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

 located on the backs of various unrelated marine and freshwater vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s, including most fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

es, marine mammals (whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

s, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...

s, and porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...

s), and the (extinct) ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...

s. Depending on the species, an animal can have up to three of them.

Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large animals, especially whales, to identify individuals in the field.

The bones or cartilages that support the dorsal fin are called pterygiophores.

The dorsal fin is probably best known as the visible sign of an approaching shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

.


The main purpose of the dorsal fin is to stabilize the animal against rolling and to assist in sudden turns.
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Encyclopedia
A dorsal fin is a fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

 located on the backs of various unrelated marine and freshwater vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s, including most fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

es, marine mammals (whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

s, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...

s, and porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...

s), and the (extinct) ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...

s. Depending on the species, an animal can have up to three of them.

Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large animals, especially whales, to identify individuals in the field.

The bones or cartilages that support the dorsal fin are called pterygiophores.

The dorsal fin is probably best known as the visible sign of an approaching shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

.

Functions



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
Molidae
Molidae is the family of the molas or ocean sunfishes, unique fish whose bodies come to an end just behind the dorsal and anal fins, giving them a "half-a-fish" appearance...

 uses the dorsal fin (and the anal fin) for propulsion. In anglerfish
Anglerfish
Anglerfishes are members of the teleost order Lophiiformes . They are bony fishes named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfishes are pelagic , while others are benthic...

, 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
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

 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 the spiny dogfish
Spiny dogfish
The spiny dogfish, spurdog, mud shark, or piked dogfish, Squalus acanthias, is one of the best known of the dogfish which are members of the family Squalidae in the order Squaliformes. While these common names may apply to several species, Squalus acanthias is distinguished by having two spines ...

 and the Port Jackson shark
Port Jackson shark
The Port Jackson shark, Heterodontus portusjacksoni, is a nocturnal, oviparous type of bullhead shark of the family Heterodontidae, found in the coastal region of southern Australia, including the waters off Port Jackson. It has a large head with prominent forehead ridges and dark brown...

 have spines in their dorsal fins which are capable of secreting poison.
In the case of the electric eel
Electric eel
The electric eel , is an electric fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, of up to six hundred volts, which it uses for both hunting and self-defense. It is an apex predator in its South American range...

, the role of the dorsal fin is taken by an anal fin.

See also


  • Fish anatomy
    Fish anatomy
    Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...


A dorsal fin is a fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

 located on the backs of various unrelated marine and freshwater vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s, including most fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

es, marine mammals (whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

s, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...

s, and porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...

s), and the (extinct) ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...

s. Depending on the species, an animal can have up to three of them.

Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large animals, especially whales, to identify individuals in the field.

The bones or cartilages that support the dorsal fin are called pterygiophores.

The dorsal fin is probably best known as the visible sign of an approaching shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

.

Functions



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
Molidae
Molidae is the family of the molas or ocean sunfishes, unique fish whose bodies come to an end just behind the dorsal and anal fins, giving them a "half-a-fish" appearance...

 uses the dorsal fin (and the anal fin) for propulsion. In anglerfish
Anglerfish
Anglerfishes are members of the teleost order Lophiiformes . They are bony fishes named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfishes are pelagic , while others are benthic...

, 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
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

 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 the spiny dogfish
Spiny dogfish
The spiny dogfish, spurdog, mud shark, or piked dogfish, Squalus acanthias, is one of the best known of the dogfish which are members of the family Squalidae in the order Squaliformes. While these common names may apply to several species, Squalus acanthias is distinguished by having two spines ...

 and the Port Jackson shark
Port Jackson shark
The Port Jackson shark, Heterodontus portusjacksoni, is a nocturnal, oviparous type of bullhead shark of the family Heterodontidae, found in the coastal region of southern Australia, including the waters off Port Jackson. It has a large head with prominent forehead ridges and dark brown...

 have spines in their dorsal fins which are capable of secreting poison.
In the case of the electric eel
Electric eel
The electric eel , is an electric fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, of up to six hundred volts, which it uses for both hunting and self-defense. It is an apex predator in its South American range...

, the role of the dorsal fin is taken by an anal fin.

See also


  • Fish anatomy
    Fish anatomy
    Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...


A dorsal fin is a fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

 located on the backs of various unrelated marine and freshwater vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s, including most fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

es, marine mammals (whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

s, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...

s, and porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...

s), and the (extinct) ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...

s. Depending on the species, an animal can have up to three of them.

Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large animals, especially whales, to identify individuals in the field.

The bones or cartilages that support the dorsal fin are called pterygiophores.

The dorsal fin is probably best known as the visible sign of an approaching shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

.

Functions



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
Molidae
Molidae is the family of the molas or ocean sunfishes, unique fish whose bodies come to an end just behind the dorsal and anal fins, giving them a "half-a-fish" appearance...

 uses the dorsal fin (and the anal fin) for propulsion. In anglerfish
Anglerfish
Anglerfishes are members of the teleost order Lophiiformes . They are bony fishes named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfishes are pelagic , while others are benthic...

, 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
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

 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 the spiny dogfish
Spiny dogfish
The spiny dogfish, spurdog, mud shark, or piked dogfish, Squalus acanthias, is one of the best known of the dogfish which are members of the family Squalidae in the order Squaliformes. While these common names may apply to several species, Squalus acanthias is distinguished by having two spines ...

 and the Port Jackson shark
Port Jackson shark
The Port Jackson shark, Heterodontus portusjacksoni, is a nocturnal, oviparous type of bullhead shark of the family Heterodontidae, found in the coastal region of southern Australia, including the waters off Port Jackson. It has a large head with prominent forehead ridges and dark brown...

 have spines in their dorsal fins which are capable of secreting poison.
In the case of the electric eel
Electric eel
The electric eel , is an electric fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, of up to six hundred volts, which it uses for both hunting and self-defense. It is an apex predator in its South American range...

, the role of the dorsal fin is taken by an anal fin.