This article may need to be rewritten entirely to comply with Wikipedia's quality standards. You can help. The discussion page may contain suggestions. (April 2009)

This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (June 2009)

A dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the (extinct) ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns. The bones that support the dorsal fin are called Pterygiophore.

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

Contents 1 Functions 2 See also 3 Notes 4 References

[edit] Functions

Though the primary use of the dorsal fin in most animals is to protect the fish against rolling, and assists in sudden turns and stops, some species have adapted their dorsal fins to other uses. In anglerfish, the anterior of the dorsal fin is modified into an illicium and esca, a biological equivalent to a fishing pole and a lure. 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 the Spiny Dogfish and the Port Jackson shark have spines in their dorsal fins which are capable of secreting poison.

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

[edit] See also

• Fish anatomy

[edit] Notes

[edit] References

v • d • e About fish About fish Diversity of fish · Fish development · Spawning · Spawning triggers · Roe · Capacity for pain · Diseases and parasites · Fishing · Fear of fish · Ichthyology · Prehistoric fish Anatomy Fish anatomy · Ampullae of Lorenzini · Anguilliformity · Barbel · Clasper · Dermal denticle · Dorsal fin · Electroreception · Gas bladder · Gill · Gill slit · Glossohyal · Leydig's organ · Operculum · Pharyngeal teeth · Photophore · Pseudobranch · Shark cartilage · Shark tooth · Scales · Weberian apparatus · Digital Library Habitats Coastal fish · Coldwater fish · Deep sea fish · Demersal fish · Freshwater fish · Groundfish · Pelagic fish · Reef fish · Tropical fish · Wild fish Locomotion Fish locomotion · Fin and flipper locomotion · Amphibious fish · Walking fish · Flying fish · Undulatory locomotion Behaviour Bottom feeders · Cleaner fish · Electric fish · Filter feeders · Forage fish · Hallucinogenic fish · Migrating fish · Paedophagy · Predatory fish · Scale eaters · Schooling fish · Venomous fish Other types Bait fish · Farmed fish · Game fish · Oily fish · Rough fish · Whitefish Lists Aquarium fish · Fish common names · Fish families · Fish on stamps · Ichthyology terms