Scientists think a swordfish uses its sword when it hunts for food. Squid and cuttlefish eaten by swordfish often show slash marks on their bodies, and a study found that most large fish eaten by swordfish had been slashed, while small prey were eaten whole. The study compared large prey with small prey, and the marks show up on the large ones, which is the first clue and one that comes from the food itself.

The mouth adds to the clue. Swordfish have no teeth and swallow their food whole, which limits the size of prey they can handle. A grown swordfish has no teeth and no scales. In the same study, small prey items had been consumed whole, while most large fish prey had been slashed. Scientists think a swordfish uses its sword when it hunts for food, and these are the facts they work with: the marks, the mouth and the study.

The bill is a substantial part of the fish. It may be one-third of the fish's total length, and, as of November 2026, a swordfish can grow to about 177 inches long, counting from the tip of its bill to the end of its tail. A swordfish's bill streamlines the fish for swimming and also helps it catch prey. A swordfish's bill is longer than the bills of other billfishes, and it is flat, shaped like a flattened oval across, and the fish is also called a broadbill.

A swordfish eats fishes such as Atlantic mackerel, barracudinas, silver hake, redfish, herring and lanternfishes. It also eats squid. Swordfish feed at many depths, from near the surface into deep water. Tagged swordfish off Florida typically spent the day about 550 meters, a third of a mile, deep, and swordfish hunt in water as cold as three degrees Celsius several hundred meters below the surface. At night they swim up near the surface to feed. Swordfish live in oceans around the world.

Words to know

• billfishes: long-billed fish
• streamlines: shapes smoothly
• whole: in one piece