Barracuda (Julia Koeffender / CC BY)

The barracuda (Sphyraena sp.) has a slender, streamlined body and a large mouth with a jutting lower jaw and large teeth. Its small scales are smooth to the touch. Their coloration is typically brownish or bluish gray. Their backs may have several dark bars. Barracudas can reach up to 1.8 meters (5.9 feet) in length. At times they attack humans. Divers should remove shiny items like rings or jewelry before entering water inhabited by barracudas, because these items are sometimes mistaken for prey.

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This supplemental online resource accompanies the book Scuba Diving Hand Signals by Lars Behnke, available on Amazon.