Tunas Barracudas Marlins and Relatives: Scombroidei

Barracudas, tunas, marlins, and their relatives have streamlined bodies. They are medium-sized (about 2 feet or 61 centimeters) to huge (16 feet or 5 meters) and are extremely fast swimmers. Some can leap high out of the water. Some of these fishes have nets of tiny blood vessels in their bodies that help them keep cool during their intense physical efforts.

Barracudas, tunas, marlins, and their relatives live all over the world.

Most barracudas, tunas, marlins, and their relatives live in the open sea, usually near the surface. Some live in middle depths, and some live in estuaries (EHS-chew-air-eez), or the areas where rivers meet the sea. One species moves long distances upriver.

Most barracudas, tunas, marlins, and their relatives hunt for fish, squid, and crustaceans (krus-TAY-shuns), or water-dwelling animals that have jointed legs and a hard shell but no backbone. Some eat plankton, or microscopic plants and animals drifting in water.

Some barracudas, tunas, marlins, and their relatives form large schools, but others live alone. They all spawn in groups. The eggs float freely and hatch into free-floating larvae (LAR-vee), which are an early stage that must change form before becoming adults.

The World Conservation Union (IUCN) lists one species of barracudas, tunas, marlins, and their relatives as Critically Endangered, one as Endangered, and one as Vulnerable. Critically Endangered means facing an extremely high risk of extinction in the wild. Endangered means facing a very high risk of extinction in the wild. Vulnerable means facing a high risk of extinction in the wild.