Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Xiphiidae
Genus: Xiphias
Species: Xiphias gladius
This is the sole member of family Xiphiidae. Swordfish are ectothermic animals. However, they have special organs next to their eyes to heat their eyes and brains 10-15oC above the surrounding water temperature. The heating of the eyes greatly improves their vision, and consequently improves their ability to catch prey. Among more than 25,000 fish species, only 22 are known to have a mechanism to conserve heat. These include the swordfish, marlin, tuna, and some sharks.
They commonly reach 9.8 ft (3m) in length, and the maximum reported is 14.9 ft (4.55m) in length and 1,430 lb (650 kg) in weight. Swordfish have been fished widely since ancient times, among others in the Mediterranean Sea. It is a typical dish in the cuisine of this region. Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as 33 ft (10m) from a neighboring swordfish.
Swordfish are vigorous, powerful fighters. When hooked or harpooned, they have been known to dive so quickly, they have impaled their swords into the ocean bottom up to their eyes. Although no unprovoked attacks on humans have been reported, swordfish can be very dangerous when harpooned.
Sport fishers and photographers are interested in Swordfish, and capture their great and powerful jumping out of the sea as beautiful sights. This breaching may be an effort to dislodge pests. Swordfish were harvested by a variety of methods at small scale (notably harpoon fishing) until the global expansion of long-line fishing.
Swordfish are classified as oily fish. Many sources, including the United States Food and Drug Administration, warn about potential toxicity from level of methyl-mercury in Swordfish. The FDA recommends that young children, pregnant women, and women of child-bearing age not eat much Swordfish.
Swordfish is particularly popular in fine cuisine. The demand and annual world catch is remarkably growing. Therefore, they are listed as a threatened species. In 2010, Greenpeace International has added Swordfish to its seafood red list.