A barracuda hunts by ambush: it lies in wait and then surprises its prey. A great barracuda finds its prey mostly by sight. In high-speed video, a barracuda lines its body up with the prey and then lunges head-on, starting the lunge with an S-shaped bend of the body (an 's-start').

Researchers filmed five individuals of each of three fish species with high-speed video. They measured an average strike velocity of 144 cm/s for the great barracuda, compared with 64 cm/s for the redfin needlefish.

A great barracuda closes its jaws only after the prey is already inside its mouth. The prey is carried in by the barracuda's own forward motion, with no handling in the mouth. Gar and needlefish can spend up to 7000 milliseconds handling prey in the mouth.

To study how a barracuda's jaws work, scientists from the Field Museum examined barracuda from 20 g to 8.2 kg, dissected fresh specimens, and filmed biting at 1500 frames per second. A computer model of the jaw predicted a bite force at the lower jaw of as high as 9 newtons in large barracuda. This is a prediction from jaw anatomy, not a force measured on a living fish.

The Florida Museum of Natural History estimates that the top speed of a great barracuda may be as fast as 36 mph (58 km/h). It is an estimate for the species, not a measured speed. The biggest great barracudas grow to about 2 meters (6.5 feet) long, with a long, slim body shaped like a torpedo.

Great barracudas eat jacks, grunts, groupers, snappers, small tunas, mullets, killifishes, herrings and anchovies, among other fish. A barracuda swallows small fish whole and cuts bigger fish into pieces to swallow. Some of its teeth face backward, which helps it keep its grip on slippery prey.

A young great barracuda is recognizable as a miniature adult at about 1.3 cm long, and it spends the rest of its first year in mangrove and seagrass habitats. A male is about 2 years old, and a female about 4, when they can first breed. A great barracuda does not look after its eggs.

Scientists still do not agree on when and where great barracudas spawn. One source reports spring, another says it follows phases of the moon, and another says year-round except winter. The Florida Museum says the timing and place of great barracuda spawning have not been well documented. It is believed to take place in deeper, offshore waters.

Words to know

• ambush: wait and surprise
• velocity: speed and direction
• newtons: units of force
• spawn: lay eggs
• specimens: collected animals