The gastric-brooding frogs are a genus, Rheobatrachus, of frogs from East Australia. The genus contains only two species, and the assignment to a taxonomic family is being hotly debated - some class them with the Myobatrachidae, but others put them in their own family Rheobatrachidae.^[1] Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Typical Classes Subphylum Urochordata - Tunicatas Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... For other uses, see Amphibian (disambiguation). ... Suborders Archaeobatrachia Mesobatrachia Neobatrachia The Anura is the order of animals in the class Amphibia that includes frogs and toads. ... Families Allophrynidae Arthroleptidae Astylosternidae Brachycephalidae Bufonidae Centrolenidae Dendrobatidae Heleophrynidae Hemisotidae Hylidae Hyperoliidae Leptodactylidae Limnodynastidae Mantellidae Microhylidae Myobatrachidae Nasikabatrachidae Petropedetidae Ranidae Rhacophoridae Rheobatrachidae Rhinodermatidae Sooglossidae Neobatrachia are a suborder of order Anura, i. ... Genera Adelotus Arenophryne Assa Bryobatrachus Crinia Geocrinia Heleioporus Lechriodus Limnodynastes Metacrinia Mixophyes Myobatrachus Neobatrachus Notaden Paracrinia Philoria Pseudophryne Rheobatrachus Spicospina Taudactylus Uperoleia Myobatrachidae is a family of order Anura. ... In biology, a genus (plural genera) is a taxonomic grouping. ... Distribution of frogs (in black) Suborders Archaeobatrachia Mesobatrachia Neobatrachia - List of Anuran families A frog is an amphibian in the order Anura (meaning tail-less from Greek an-, without + oura, tail). ... Genera Adelotus Arenophryne Assa Bryobatrachus Crinia Geocrinia Heleioporus Lechriodus Limnodynastes Metacrinia Mixophyes Myobatrachus Neobatrachus Notaden Paracrinia Philoria Pseudophryne Rheobatrachus Spicospina Taudactylus Uperoleia Myobatrachidae is a family of order Anura. ...

The animals are remarkable for being the only terrestrial vertebrates to incubate the prejuvenile stages of their offspring in the stomach of the mother. Both species are considered extinct today.

Species and distribution

The Southern Gastric-brooding Frog (Rheobatrachus silus Liem, 1973) was discovered in 1972 and first described in 1973. However, there is one publication suggesting the species may have been discovered in 1914. R. silus inhabited the Blackall-Conondale Range in Southeast Queensland, North of Brisbane, between 400 and 800 metres above sea level. The rain forest habitat was limited to less than 1,000 square kilometres. Depending on the source, the species is described as missing since 1979 or 1982. The last captive specimen died in 1984. Emblems: Faunal - Koala (Phascolarctos cinereus); Floral - Cooktown orchid (Dendrobium bigibbum); Bird - Brolga (Grus rubicunda); Aquatic - Barrier Reef Anemonefish (Amphiprion akindynos); Gem - Sapphire; Colour - Maroon Motto: Audax at Fidelis (Bold but Faithful) Slogan or Nickname: Sunshine State, Smart State Other Australian states and territories Capital Brisbane Government Governor Premier Const. ... Brisbane is the capital and most populous city in the state of Queensland, Australia. ...

The Northern Gastric-brooding Frog (Rheobatrachus vitellinus Mahony, Tyler & Davis, 1984) was only discovered in 1984. It inhabited the Clarke Range in central Northeastern Queensland. This species, too, was confined to a small area - less than 500 square kilometres, between 400 and 1000 metres in altitude. Only a year after its discovery, it was never seen again and is therefore classified extinct.

Physical description

The gastric-brooding frogs are small frogs of dull colouration, with protruding eyes positioned close together and a short, blunt snout. Their skin is moist and coated with mucus. The fingers are long, and unwebbed, the feet are webbed and the legs are large in comparison to the body. The Southern Gastric Brooding Frog is a dull grey to slate colour, with small patches, both dark and light. The ventral surface is white or cream, occasionally with yellow blotches. The male Southern Gastric Brooding Frog is between 33 and 41 millimetres in length and females 44 to 54 millimetres in length.

The Northern Gastric Brooding Frog is a much larger frog, males reaching a size of 50-53 millimetres in length, and females 66-79 millimetres in length. This species is much darker in colour, usually brown, and its skin is bumpy and slimey. The ventral surface consists of vivid yellow blotches on a white or grey background. The body shape of the Northern Gastric Brooding Frog is very similar to the southern species.

Ecology and behaviour

The curiosity with these frogs is their unique parental care: following external fertilisation by the male, the female would take the eggs into its mouth and swallow them. It is not clear, however, whether the females swallowed the tadpoles or the eggs, as it was never observed prior to their extinction.

The ingested progeny produced the hormone prostaglandin E2, which inhibited production of gastric juices. The first few offspring to be swallowed are ingested, as prostaglandin E2 takes time to take full effect. While the larvae developed in a quasi-uterus, the female could not eat. After approximately two months, the fully metamorphosed offspring climbed from the mouth of their mother. This could be as many as 25 individuals. A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Chemical structure of prostaglandin E1 (PGE1). ... The uterus or womb is the major female reproductive organ of most mammals, including humans. ...

Cause for extinction

The cause for the gastric-brooding frogs' extinction is unknown. A direct threat to the habitats through human activities was not clearly apparent. Chytrid fungi may have contributed. Orders Chytridiales Spizellomycetales Blastocladiales Monoblepharidales Neocallimasticales Chytridiomycota is a division of the Fungi kingdom and contains only one class, Chytridiomycetes. ...

References

Much of the content of this article comes from the equivalent German-language Wikipedia article (retrieved 8th March, 2006)

1. ^ Heyer, and Liem (1976). "Analysis of the intergeneric relationships of the Australian frog family Myobatrachidae". Smithson. Contrib. Zool. 233: 14.

• Pough, F. H., R. M. Andrews, J. E. Cadle, M. Crump, A. H. Savitsky & K. D. Wells: Herpetology (3rd edition). – Pearson Prentice Hall, Upper Saddle River, New Jersey, 2003.
• Ryan, M. (Ed.): Wildlife of Greater Brisbane. – Queensland Museum, Brisbane, 2003.
• Ryan, M. & C. Burwell (Ed.): Wildlife of Tropical North Queensland. – Queensland Museum, Brisbane, 2003.
• Tyler, M. J.: There’s a frog in my throat/stomach. – William Collins Pty Ltd, Sydney, 1984. ISBN 0-00-217321-2
• Zug, G. E., L. J. Vitt & J. P. Caldwell: Herpetology (2nd edition). – Academic Press, San Diego, California, 2001.

External links

• Queensland Museum: "Frogs"
• Detailed information about Rheobatrachus silus