Barracudas are found world-wide in all warm and tropical waters, and are usually spotted in shallow water close to coral reefs and seagrass beds. There are four species regularly spotted while diving from Koh Lanta.
Fast, powerful, and known for their often fearsome appearance, they have long, thin, elongated bodies, with some species growing up to 2 m.
The upper body is generally grey or silvery coloured, with a dark blue or dark green colouration, and the lower body is whitish.
Body markings vary by species, typically with stripes, chevrons, spots and blotches helping to distinguish species from one another.
Barracudas have two short, widely separated dorsal fins, a forked tail fin, and small scales. Their fins may be yellowish or dusky.
The characteristic pike-like head is long, thin, and pointed, with a large under-bite in many species. Large, sharp, fang-like teeth protrude noticeably from the jaw, creating a menacing and threatening appearance.
Some species, such as the great barracuda (Sphyraena barracuda) are usually seen alone in shallow parts of the reef around Koh Lanta, however other species can be seen both in small groups, and in very large schools of several thousand individuals.
Barracudas are ambush predators, mostly lying in wait to prey on smaller fish. Although incidents are rare, the great barracuda has been known to attack swimmers by mistake.
Remove shiny jewellery and diamond rings when diving or snorkeling, as these objects are known to attract a great barracuda's attention and may appear attractive to them.