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Dorsal fin

 
Dorsal Fin

 
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Dorsal fin
 
 
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A dorsal fin is a fin
Fin

A fin is a surface used 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 Fish anatomy#Fins of fish, but has been extended to include other animal limbs and man-made devices....
 located on the backs of some fish
Fish

A fish is any marine biology vertebrate animal that is typically ectothermic , covered with scale , and equipped with two sets of paired fins and several unpaired fins....
, whale
Whale

Whales are marine mammals of order Cetacea which are neither dolphinsmembers, in other words, of the families Oceanic dolphin or River dolphinnor porpoises....
s, dolphin
Dolphin

File:Bottlenose_Dolphin_KSC04pd0178.jpgDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genus....
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, as well as the (extinct) ichthyosaur
Ichthyosaur

Ichthyosaurs were giant marine reptiles that resembled fish and dolphins. Ichthyosaurs thrived during much of the Mesozoic era; based on fossil evidence, they first appeared approximately 245 million years ago and disappeared about 90 million years ago, about 25 million years before the dinosaurs became extinct....
s. Its main purpose is to stabilize the animal against rolling and assist in sudden turns. Some animals have developed dorsal fins with protective functions, such as spines or venom.






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Orca Dorsalfin Noaa


A dorsal fin is a fin
Fin

A fin is a surface used 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 Fish anatomy#Fins of fish, but has been extended to include other animal limbs and man-made devices....
 located on the backs of some fish
Fish

A fish is any marine biology vertebrate animal that is typically ectothermic , covered with scale , and equipped with two sets of paired fins and several unpaired fins....
, whale
Whale

Whales are marine mammals of order Cetacea which are neither dolphinsmembers, in other words, of the families Oceanic dolphin or River dolphinnor porpoises....
s, dolphin
Dolphin

File:Bottlenose_Dolphin_KSC04pd0178.jpgDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genus....
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, as well as the (extinct) ichthyosaur
Ichthyosaur

Ichthyosaurs were giant marine reptiles that resembled fish and dolphins. Ichthyosaurs thrived during much of the Mesozoic era; based on fossil evidence, they first appeared approximately 245 million years ago and disappeared about 90 million years ago, about 25 million years before the dinosaurs became extinct....
s. Its main purpose is to stabilize the animal against rolling and assist in sudden turns. Some animals have developed dorsal fins with protective functions, such as spines or venom. Many catfish
Catfish

Catfish are a very diverse group of Actinopterygii fish. Named for their prominent barbel s, which resemble a cat's whiskers , catfish range in size and behavior from the heaviest, the Pangasius gigas from Southeast Asia and the longest, the wels catfish of Eurasia, to detritivores , and even to a tiny parasite species commonly called the ca...
 can lock the leading ray of the dorsal fin in an extended position to discourage predation or to wedge themselves into a crevice.

Dorsal fins come in a variety of shapes and sizes.

They are infamous for being the sign of an approaching shark
Shark

Sharks are a type of fish with a full Cartilage skeleton and a highly Streamlines, streaklines and pathlinesd body. They respire with the use of five to seven gill slits....
.

Most whales, dolphins, and porpoises possess dorsal fins.

In relation to the size of the creature, the dorsal fin of the male orca is quite large, as much as 1.8 m high. Female orcas have shorter dorsal fins that are more curved. The Marine Life Information Network for Britain & Ireland/Marine Biological Association of the United Kingdom. 30% to 100% of captive male killer orcas experience collapse of the dorsal fin, possibly because lack of exercise through turning leads to diminished muscle tone, other possible factors include change in diet, sex drive and pressure in the pool due to counter-clockwise swimming, this reacts with the sodium nitrate in the whale's pituitary gland and leads to the loss of connective tissue in the dorsal area. Only about 1% of wild orcas have collapsed dorsal fins. The dorsal fins of most other whales are relatively small. The bowhead whale has no dorsal fin at all, as an evolutionary adaptation to its life spent cruising under icepack. The dorsal fins of whales develop distinctive nicks and wear patterns with time, and this fact is used by wildlife biologists to identify individuals in the field.