Two African frog species are favored as pets: the African dwarf frog and the African clawed frog. You can tell these two apart because the clawed frog is substantially larger. Finding out the sex of either frog species, though, takes a bit of close-up observation.
African Dwarf Frog
The tiny African dwarf frogs grow to about 1.5 inches long. Females are usually larger than males, but without a known-gender comparison frog on hand, that fact's of little use. Lift the frogs up and look for signs of a white bump on the back of each front leg. This subdermal gland indicates a male. During mating it should be easier to spot the difference: the male is the frog clinging to the back of the female. During the mating season, the male frogs sing to attract females. Occasionally females do sing in response, but vocalization is more specifically a male activity.
African Clawed Frog
The male African clawed frog species measures about 2.5 inches. However, while the male weighs a mere 2 ounces, the female is a whopping 7 ounces on average and measures about 4.5 inches long. The male has no vocal cords, unlike males of other frog species. You can spot a female from the cloacal sac at the end of her abdomen, where she excretes waste.
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Based in London, Eleanor McKenzie has been writing lifestyle-related books and articles since 1998. Her articles have appeared in the "Palm Beach Times" and she is the author of numerous books published by Hamlyn U.K., including "Healing Reiki" and "Pilates System." She holds a Master of Arts in informational studies from London University.