Sailfish

Sailfish Fossil range: Middle Miocene to Present
Indo-Pacific sailfish, Istiophorus platypterus
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Family: Istiophoridae Genus: Istiophorus Lacépède, 1801
Species
2, see text

Sailfish is the common name for any of the large marine fish comprising the genus Istiophorus in the Istiophoridae family of the Perciformes order, characterized by a dorsal fin that is very long, sail shaped, and taller than body depth and by an elongated premaxillary bill resembling that of the swordfish and other billfish.

There are two extant species of sailfishes, the Atlantic sailfish (Istiophorus albicans), common to the Atlantic Ocean, and the Indo-Pacific sailfish (Istiophorus platypterus), native to the Indian and Pacific Oceans. The Indo-Pacific sailfish may be the fastest fish in the ocean.

Sailfish are highly prized game fish and are known for their incredible jumps.

Description

Sailfish are part of the Xiphiidae family of the suborder Scombroidei. The suborder includes species that likely are the fastest swimming fish in the world, including bluefin tuna, swordfish, and sailfish (Nelson 1994, p. 424). Other members of the suborder include barracudas, mackerels, and snake mackerels. Members of the suborder are characterized by an upper jaw that is not protrusible, with the premaxilla fixed (an adaptation to feeding on larger prey) (Nelson 1994, p. 424).

The Xiphiidae family includes fish known as billfishes, including the swordfish, sailfishes, marlins, and spearfishes. There are four genera with 12 species in the family. This group is characterized by adults having an elongate, premaxillary bill (or rostum), as well as an inferior moth, the dorsal fin beginning over the back of the head, and the dorsal fin lacking any true spines and from 37 to 55 rays (Nelson 1994, p. 428). They also lack finlets behind the dorsal and anal fins, have two anals rays, the pectoral fins are inserted low on the body, the pelvic fins are reduced (one spine and two rays or absent), and the gill membranes are free from the isthmus (Nelson 1994, p. 428).

The Xiphiidae are a taxon of fish with the remarkable ability to practice a form of endothermy, a type of warm-bloodedness where an elevated body temperature is maintained through internal means. Billfish exhibit a type of endothermy known as cranial endothermy whereby only the brain and eyes are warmed (Nelson 1994; Block et al. 1993). They remain "cold-blooded" (specifically poikilothermic) in that they do not maintain constant internal temperatures and the temperature often mirrors the ambient temperature. But by being able to raise the temperature of their brains and eyes, they can have faster eye movements when hunting, which is valued when diving deep into the ocean where the water is very cold.

Within the family Xiphiidae, Nelson (1994) recognizes two subfamilies. Xiphiinae, with just one extant species, the swordfish (Xiphias gladius), and Istiophorinae, with three genera and 11 species, including the sailfishes. Istiophorinae, and thus sailfishes, are characterized by a rounded bill, elongate pelvic fins, scales (the swordfish in subfamily Xiphiinae lacks scales in adult), jaws with teeth (the swordfish lacks teeth in the adult), a lateral line throughout life, and 24 vertebrae (the swordfish has 26 vertebrae) (Nelson 1994, p. 428). Most prominent of the Istiophorinae is the dorsal fin, which has a very long base, which is sail-like in some species, and is depressible into groove (Nelson 1994, p. 428). The three genera that Nelson (1994) places in this subfamily are Istiophorus (sailfishes), Tetrapturus (spearfishes), and Makaira (marlins).

What distinguishes the sailfish from other members of the subfamily and family is the shape of its dorsal fin and pelvic fin. The first dorsal fin is sail shaped and distinctly higher than the body depth and the rays of the pelvic fin are very long (Nelson 1994, p. 429). The sail is normally kept folded down and to the side when swimming, but it may be raised when the sailfish feels threatened or excited, making the fish appear much larger than it actually is. This tactic has also been observed during feeding, when a group of sailfish use their sails to "herd" a school of fish or squid.

As with other members of the family, the elongate premaxillary bill is used to stun fish by slashing back and forth (Nelson 1994, p. 428).

Both species of sailfishes grow quickly, reaching 1.2-1.5 m (4-5 ft) in length in a single year, and feed on the surface or at mid-depths on smaller pelagic fishes and squid. Individuals have been clocked at speeds of up to 110 km/h (68 mph), which is the highest speed reliably reported in a fish. Generally, sailfish do not grow to more than 3 m (10 ft) in length and rarely weigh over 90 kg (200 lb), although larger specimens have been seen off the shores of Costa Rica.^{[citation needed]}

• Block, B. A., J. R. Finnerty, A. F. R. Stewart, and J. Kidd. 1993. Evolution of endothermy in fish: Mapping physiological traits on a molecular phylogeny. Science 260: 210-214.

• Nelson, J. S. 1994. Fishes of the World, 3rd ed. New York: John Wiley & Sons. ISBN 0471547131.

Species

Atlantic sailfish

(Istiophorus albicans).

Atlantic sailfish
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Family: Istiophoridae Genus: Istiophorus Lacépède, 1801 Species: I. albicans
Binomial name
Istiophorus albicans (Latreille, 1804)

The Atlantic sailfish, Istiophorus albicans, is a species of marine fish in the family Istiophoridae of the order Perciformes. It is found in the Atlantic Oceans and the Caribbean Sea, except for large areas of the central North Atlantic and the central South Atlantic, from the surface to depths of 200 m.

Length is up to 3.15 m, and the maximum published weight is 58.1 kg.

Indo-Pacific sailfish

(Istiophorus platypterus).

Indo-Pacific sailfish
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Family: Istiophoridae Genus: Istiophorus Lacépède, 1801 Species: I. platypterus
Binomial name
Istiophorus platypterus (Shaw, 1792)

The Indo-Pacific sailfish, Istiophorus platypterus, is a sailfish native to the Indian and Pacific Oceans. It is dark blue on top, brown-blue laterally, silvery white underbelly; upper jaw elongated in form of spear; first dorsal fin greatly enlarged in the form of a sail, with many black spots, its front squared off, highest at its midpoint; pelvic fins very narrow, reaching almost to the anus; body covered with embedded scales, blunt at end; lateral line curved above pectoral fin, then straight to base of tail.they have a large and sharp bill, that they use for hunting. They feed on tuna and mackerel, some of the fastest fish in the Ocean. They are able to prey on the faster fish in the sea because their top speed has been clocked at 68 mph, making them the fastest fish in the ocean.

References

ISBN links support NWE through referral fees

• Sepkoski, J. 2002. A compendium of fossil marine animal genera. Bulletins of American Paleontology 364: 560. Retrieved May 22, 2008.

• Istiophorus platypterus (TSN 172488). Integrated Taxonomic Information System. Accessed on 18 April 2006.
• Template:FishBase species

• Istiophorus albicans (TSN 550888). Integrated Taxonomic Information System. Accessed on 6 June 2006.
• Template:FishBase species

• "Istiophorus". FishBase. Ed. Ranier Froese and Daniel Pauly. March 2008 version. N.p.: FishBase, 2008.

External links

• Sailfish Pictures

Credits

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