African Dwarf Frog

African dwarf frogs occur in forested parts of equatorial Africa, from Nigeria and Cameroon in the north, and south through Gabon and east throughout the Congo River Basin.

There are four species: * Zaire dwarf clawed frog, Hymenochirus boettgeri Tornier, 1896 * Eastern dwarf clawed frog, Hymenochirus boulengeri De Witte, 1930 * Western dwarf clawed frog, Hymenochirus curtipes Noble, 1924 * Gaboon dwarf clawed frog, Hymenochirus feae Boulenger, 1906

Males are slim and develop a small gland behind each of their front legs; this gland is not very well understood but is believed to play some part in mating. The gland is a small white spot on both sides, a minor outward bulge on both sides of the frog. Males are known to "sing" or "hum" during mating or when excited, although they sometimes "hum" even if they have no intention of mating. The females of this species are 40% larger than males when fully mature. They have pear-shaped bodies, as their abdomens fill with eggs as they reach a mating stage. Another distinction is the females have a more pronounced genital region, called an ovipositor. African dwarf frogs mate in amplexus, during which the male grabs the female around the abdomen just in front of its back legs. The female becomes motionless, and its front limbs may twitch sporadically. Amplexus usually happens at night after one or more nights of "humming" by the male. During amplexus, the female swims, laying eggs on the surface of the water, one at a time, whilst towing the male. The female swims to the bottom between layings. The male fertilizes the eggs during this time by releasing sperm into the water. Amplexus can last for several hours. When the female has laid all its eggs, it signals the male once more by going motionless, and after several minutes, the male releases the female and it returns to its normal behavior.