Amphibians · Anura · Myobatrachidae

Southern Gastric Brooding Frog

Rheobatrachus silus

Extinct

No living individual remains anywhere in the world. See full glossary

The southern gastric-brooding frog is an extinct anuran amphibian of the family Myobatrachidae. It was the only animal known to be able to brood its eggs in its stomach, which it managed by apparently switching off its digestive enzymes by means of a substance produced by the eggs. This frog became extinct in 2002. Scientists at the University of New South Wales announced in March 2013 that the species was part of the Lazarus Project, which seeks to revive extinct species by cloning; they have managed to clone some embryos, but none has survived. In early 2020 geneticists at the University of New South Wales obtained fertile embryos of this species which will soon develop.

Size

3 cm – 5 cm

Diet

Insectivore

Feeds mainly on insects and other invertebrates.

Activity

Nocturnal

Active mainly at night.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Impossible (extinct)

RainforestMountainFreshwaterInsectivore Nocturnal Solitary Amphibian Rainforest Mountain Freshwater

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Fun facts

The female swallowed the fertilised eggs and the tadpoles developed in her stomach, which stopped producing hydrochloric acid altogether for six weeks thanks to a substance secreted by the young themselves. The mother did not eat in all that time and gave birth through her mouth.
Its disappearance was sudden: it was described in 1973, studied intensively for eight years, and by 1981 could no longer be found. A second species of the same genus, discovered in 1984, vanished in 1985.
The Lazarus Project has been trying since 2013 to bring it back by cloning from frozen tissue: early embryos have been obtained, but none has reached the tadpole stage.
It brooded its young in its stomach. The female swallowed the fertilised eggs and incubated them inside for six or seven weeks, until giving birth through her mouth to fully formed young.
To avoid digesting them, she stopped producing hydrochloric acid. This is achieved by a substance, prostaglandin E2, present in the egg jelly and later excreted by the tadpoles' gills, which switches off the mother's acid secretion.
During those weeks the female ate nothing, and with her stomach distended she stopped breathing with her lungs and switched to breathing through her skin.
It was discovered in 1972 and its mode of reproduction was described in 1974. It was last seen in the wild in 1981 and the last captive individual died in 1983.
Its disappearance cut short a promising line of medical research: understanding how it switched off gastric acid production could have helped in treating ulcers and in recovery after stomach surgery.
Since 2013 the Lazarus Project has been trying to clone it by nuclear transfer using the eggs of another frog. Early embryos have been obtained, but none has reached the tadpole stage.

Life cycle & biology

Skeleton type: Vertebrate - internal bony skeleton (amphibian)
Habitat & environment: Rainforest streams of the Blackall and Conondale Ranges, in Queensland, Australia
Gestation / incubation: 6 weeks of development in the mother's stomach
Litter / clutch size: 25 young

Sources consulted: https://es.wikipedia.org/wiki/Rheobatrachus_silus