Probing snakes to identify gender. Top: A lubricated (water-soluble), blunt sexing probe is inserted caudally into either side of the cloaca (arrow). Middle: In males, the probe enters into one of the hemipenal sulci to a depth of 6–14 subcaudal scales. Bottom: In females, the probe enters one of the cloacal glands to a depth of <6 subcaudal scales.
Courtesy of Dr. Stephen Divers.