Crocodile flathead (Steve Childs / CC BY)

The flathead (Platycephalidae) has an elongated body and a long flattened head with bony ridges, spines, and a large mouth. Its body is covered with a pattern of green, brown, or gray blotches. Flatheads range from 13 centimeters (5.1 inches, spiny flathead) to 47 centimeters (18.5 inches, crocodile flathead) in length. They are a bottom-dwelling species that prefer the sand or rubble substrates of shallow reefs. Flatheads are harmless to humans.

Inhabits the Indo-Pacific Ocean.

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