More About Billfish


The Billfishes
Family Istiophoridae
                      © Bill Boyce
Collectively referred to as billfish, sailfish, spearfish and marlin are among the most strikingly colored and sizeable predators in the sea. They move at impressive speeds and can lunge from the water to heights of over ten feet. Because of their tremendous fighting power, they are treasured by anglers and support economically important recreational fisheries around the globe - many of which are catch-and-release. 
Formed by an extension of the upper jaw and nasal bone, their trademark bill is a specialized weapon and hunting tool used to impale or slash prey.  Larval billfish do not hatch from the egg with a bill but instead have a sharp set of tiny teeth that they use to feed voraciously, growing from a fraction of an inch to a few feet long in the first year. The bill develops when the fish are very young, between 1 and 9 inches.
Another feature shared by members of the billfish family is a specialized heat organ located in the head that regulates brain and eye temperature. Because of this adaptation, they can move with ease from warm surface waters to the cooler waters of the deep. Billfish inhabit tropical and temperate waters of the Atlantic, Pacific and Indian oceans. They are highly migratory and will follow ocean currents hundreds or even thousands of miles. Some species, such as the blue marlin, have been known cross entire oceans. 
The swordfish is sometimes grouped with billfishes because of its similar appearance, but it is actually the lone member of the family Xiphiidae and can be distinguished by the absence of scales and pelvic fins and by its more flattened and relatively longer "sword.”
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National Coalition for Marine ConservationInternational Game Fish Association