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.