Amplexus

Once a male frog has found a mate, he needs to take up a position in which he can fertilise the female's eggs. This is known as amplexus. Generally speaking, this happens outside of the female's body, straight after the eggs have been released and before the 'jelly' surrounding the eggs begins to swell. For the male's sperm to make contact with as many of his mate's eggs as possible, the male needs to position his cloaca as close as possible to hers. There are two main types and a few variations:

Inguinal amplexus
The male frogs of six primative frogs (Leiopelmatidae, Discoglossidae, Pipidaw, Rhinophrynida, Pelobatidae and Pelodytidae) and the males of some species belonging to two of the more advanced families (Myobatrachidae and Leptodactylidae) grasp the females just in front of the hind limbs. During egg-laying they bend their bodies so that the cloaca is very close to the female's.

Axillary amplexus
Males of all the other more advanced families, grasp the female directly behind the fore-limbs. This enables the cloacae to be close to each other without the male having to perform any special manoeuvre.

Cephalic amplexus
Some frogs of the Dendrobatidae (poison dart frogs) of whom all lay their eggs on land, have to take up a position where the males presses the back of his hands against the female frog's throat.

Straddle amplexus
A more unusual form happens in at least three species of ranids from Madagascar, belonging to the species Mantidactylus where the female forces her head beneath the male's hind legs while he clings to an upright leaf. As this always happens during rain, it is thought that the sperm is released on to the back of the female frog and will then flow down over the eggs as these are released by her.

Glued amplexus
For some frogs it is difficult as they have short limbs and are very rotund. For these frogs, the male secretes a sticky substance from his abdominal area and then attaches himself to the back of the female. This procedure has been confirmed in the microhylid genera Kaloula, Gastrophryne and Breviceps and is also thought to be practiced by other similarly-shaped spieces. After the eggs have been laid, the substance either breaks down or the female sheds her skin, and the animals are then free from each other.

Prolonged amplexus
Usually this whole procedure lasts for a few hours at most, but for some species it can take place for a few days or even weeks. This is so with frogs from the genus Atelopus. Males have been seen engaged with the female over a period of several months, the female continuing to feed as normal, but the male apparently unable to feed efficiently and thus becoming thinner and thinner.

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