Stingray

Stingray (Achimdiver / shutterstock.com)

Stingrays (Dasyatidae) are a group of rays characterized by barbed and venomous stingers near their tails. A stinger can reach 35 centimeters (14 inches) in length and is used exclusively in self-defense. A stingray‚Äôs sting usually causes inflammation, pain, and muscle cramps and tends to get infected from bacteria. Typically, injuries are not life threatening if no vital organ is affected. Most species of stingrays are found on the seafloor of coastal waters. They prefer sandy surfaces, which they can hide in. Coral reefs are popular feeding grounds. Some stingrays, such as eagle rays, live in open water.

skull and crossbones
Some species venomous.

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