Merck Manual

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Is That a Pit Viper?
Is That a Pit Viper?
Is That a Pit Viper?

Pit vipers have certain features that can help distinguish them from nonvenomous snakes:

  • Vertical slitlike pupils

  • Pits between the eyes and nose

  • Retractable fangs

  • Rows of single scales across the underside of the tail

  • Triangular heads (like an arrowhead)

Nonvenomous snakes tend to have the following:

  • Rounded heads

  • Round pupils

  • No pits

  • No fangs

  • Rows of double scales across the underside of the tail

If people see a snake with no fangs, they should not assume it is nonvenomous because the fangs may be retracted.

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Snakebites Snakebites