Gastric Brooding Frogs include the Northern Gastric Brooding Frog (Rheobatrachus vitellinus) and the Gastric Brooding Frog (Rheobatrachus silus). These frogs have not been seen in the wild for a number of years and are presumed extinct (R. silus was last seen in the wild in September 1981 and R. vitellinus was last seen in the wild in March 1985).
R. silus only discovered in 1972 and R. vitellinus was only found in 1984. Prior to that time, it was thought that there were no aquatic frogs in Australia. It probably took such a long time to find the frog due to its timid nature and the fact that it may be found wholly submerged in water beneath stones etc.
The Gastric Brooding Frog was a peculiar frog because, unlike most frogs, the Gastric Brooding Frog lived mainly in water.
As a water frog, the Gastric Brooding Frog had eyes on the top of its head so that it could lie in water with its eyes above the surface.
Its skin was slimy.
Its feet had extensive webbing.
These aquatic frogs were very stranger critters indeed. This is because they actually gave birth to their young via their mouths!
This is a peculiar thing for any animal to do.
Females ranged up to about 55 mm. Males ranged up to about 40mm.
The frog actually brooded its young in its stomach.
It is not known whether the mother swallowed the tadpole eggs or the tadpoles hatched and then swam into the mother's stomach.
The tadpole, unlike other tadpoles did not have a mouth or coiled intestine. The tadpole lived off its yolk sak. The tadpole also had an undeveloped tail.
As the tadpoles grew inside their mother, her stomach expanded until it occupied most of the body cavity and she could not even fully inflate her lungs. The tadpoles could move a little in the stomach.
During the brooding, the stomach did not produce hydrochloric acid.
The gestation period inside the mother was probably about 8 weeks.
A large number of tadpoles could be within the mother - for example, 30.
The mother gave birth by opening her mouth. Baby frogs came to the mouth and then gradually left (the mother kept her mouth wide open).
If a baby tadpole wouldn't leave the mother's mouth, she re-swallowed it - to be born later.
For a little more on this frog and lots of other strange frogs, have a look at Dorota's Frogland.