Fish
Great Barracuda
Sphyraena barracuda · also called barracuda, 'cuda
The great barracuda is the reef’s javelin — a long, silver, big-jawed predator built for one thing, a short and violent burst of speed. It has a fearsome look and a fearsome reputation, but the danger it poses to people is small, and the more real hazard is on the dinner plate.
Overview
Great barracuda live on and around tropical and subtropical reefs worldwide, along with seagrass flats, mangrove channels, harbours, and the open water just off the coast. Young fish grow up in the shelter of estuaries and seagrass; adults move out to deeper reef and wreck habitat. They are a familiar sight to divers throughout the Caribbean, the Indo-Pacific, and the tropical Atlantic.
Built to strike
A barracuda’s body is a cylinder tapering to a forked tail, with the propulsive fins set far back — the classic layout of a short-range sprinter. The long jaws carry two kinds of teeth: small, backward-angled ones along the outside to hold prey, and a set of large, flat, blade-like teeth set into sockets so the upper and lower teeth interlock like a zip when the mouth closes. A strike is a single lunge at up to 40 km/h, and the shearing bite frequently cuts a smaller fish in two.
Hunting
Adult great barracuda are ambush predators. A barracuda hangs still in midwater, its mirror-like flanks making it hard to see, and waits for a fish to come within range before the final rush. It hunts mostly by sight and by day. Younger barracuda school and drive baitfish cooperatively.
Their curiosity is often mistaken for aggression: a barracuda will approach and shadow a diver, apparently investigating, and is drawn to shiny, flashing objects that resemble the scales of a fleeing fish — which is the cause of most of the rare bites on humans.
Ciguatera
Because large reef barracuda sit near the top of the food chain and live a long time, they accumulate ciguatoxins produced by reef microalgae and passed up through the fish they eat. The barracuda is unharmed, but its flesh can poison a person, causing an unpleasant and sometimes long-lasting illness. Cooking does not help, and there is no visual test, so large barracuda from ciguatera-prone areas are generally not eaten.
Reproduction and status
Great barracuda spawn in open water, releasing eggs and sperm that drift as plankton before the larvae settle into shallow nursery habitat. The species is widespread, common, and listed as Least Concern. It is caught recreationally (and released, or kept from low-risk areas) and taken in some local fisheries, and it faces the same background pressures as other reef fish from habitat degradation, but it is not currently considered threatened.
Great Barracuda: common questions
Are barracuda dangerous to humans?
Rarely. Great barracuda are curious and will follow or circle a diver or snorkeller, sometimes closely, which is unnerving but not usually a prelude to an attack. The handful of bites recorded each year almost always involve a barracuda striking at a flash of shiny jewellery, a speared fish, or bait, mistaking it for prey, then releasing immediately. The injuries are clean lacerations, and unprovoked, deliberate attacks on people are essentially unknown.
Why can eating barracuda make you sick?
Ciguatera fish poisoning. Certain microalgae on tropical reefs produce toxins that are eaten by small herbivorous fish, concentrated up the food chain, and stored in the flesh of large predators like great barracuda without harming them. A person who eats an affected fish can suffer gastrointestinal illness, tingling, temperature-sensation reversal, and long-lasting neurological symptoms. The toxin is not destroyed by cooking, and there is no reliable way to tell by looking whether a fish is affected, so large reef barracuda are widely avoided as food.
How do barracuda hunt?
By ambush and speed. A great barracuda typically hangs almost motionless in the water, relying on its silvery, hard-to-see body, then covers the last few metres to its prey in a single burst so fast the prey has no time to react. Its jaws snap shut and the long inner teeth shear the victim, often cutting smaller fish clean in half; the barracuda then turns and swallows the pieces. Young barracuda hunt cooperatively in schools, herding baitfish.
Do barracuda school or live alone?
Both, by age. Juvenile and subadult great barracuda form large, loose schools over reefs and in open water, which offers protection and helps them corral prey. Fully grown adults are mostly solitary, holding a territory around a particular reef, wreck, or drop-off and tolerating other large barracuda only at a distance.