The frog I am going to discuss comes from my favourite family of frogs, the Myobatrachidae. The myobatrachidae are a family of Australian ground dwelling frogs. This is the boring description. Instead I prefer, the frogs that are so weird they lumped them together into one family.Within the myobatrachidae family is the turtle frog (Myobatrachus gouldii); pouched frog (Assa darlingtoni); Fleay’s barred Frog (Mixophyes fleayi); Southern Corroboree frog (Pseudophryne corroboree) and the gastric brooding frog (Rheobatrachus silus and Rheobatrachus vitellinus). The gastric brooding frog is the one I will be focusing on in this article but I definitely plan on discussing many of the myobactrachus family as they are all extremely fascinating. For example, the photo below features the turtle frog and anything that bizarre looking just has to be amazing.
There are two species of gastric brooding frogs and they are the southern gastric brooding frog (Rheobatrachus silus) and the northern gastric brooding frog (Rheobatrachus vitellinus). The main difference between these two species is their geographic location.
The gastric brooding famous is most famous for their method of reproduction. Frog reproduction begins (usually) with amplexus which is the frog equivalent of sexual intercourse. I have been unable to find a description of the specifics of the gastric brooding frog amplexus method but it is believed that female lays eggs that are then fertilised by the male. The fertilised eggs are then swallowed by the female. It might seem counter-intuitive to eat the eggs you just laid but nature is weird and this is how the frogs make sure their young have the best possible chance in life. Frog eggs are an extremely tasty and nutritious meal for a variety of parasites and predators. Tadpoles are also fair game for a multitude of organisms. Frogs often solve this issue by laying hundreds of eggs in the hope some may survive. Alternatively, some frogs guard their eggs until they hatch. The gastric brooding frog ultimately decided that this was not enough and the only way to keep their young safe was to eat them…
Once the eggs have been eaten by the female it will be six weeks until the juvenile frogs emerge from her mouth. The eggs whilst in the female’s stomach mature first into tadpoles and then to the adult form of a frog. This sounds simple enough but one of the most basic laws of the natural world is that energy can neither be created nor destroyed. Therefore, how are the tadpoles acquiring the energy to grow while they’re in their mother’s stomach and don’t have access to food? To further complicate matters the tadpoles lack an oral disc which is essentially a tadpole mouth. The gastric brooding frog tadpole’s oral disc however, is vestigial which, means it is not used. The answer is believed to be that the tadpole’s have a stomach filled with a yolk that will sustain them until they are regurgitated by their mother. In contrast, tadpoles of other frog species often feed on the eggs that they hatched from and eggs that are yet to hatch. The eggs usually only sustain the tadpoles through their early development until they are able to procure their own food. To be born with a stomach filled with food is quite unique. Remember, the food they are born with must sustain them until they are able to leave the relative safety of their mother’s stomach.
Now the really confounding part…. How can the female frog grow young inside of her stomach for six weeks? The stomach is a hostile environment dedicated to breaking down food. In any animal it is simply remarkable that the stomach does not digest itself. In the gastric brooding frog it manages to house its developing young in the organ dedicated to providing nutrients to the body. How does the female not digest her own young? Is the female able to feed while she is “pregnant”? How are the young able to survive the conditions of the stomach?
The best hypothesis I have come across is that the gastric brooding frog is able to ‘switch-off’ its stomach while it houses the young. The next issue is how is the female able to survive for six weeks with her stomach turned-off? We potentially have here an animal that can live without sustenance and raise its young for six weeks. The scientific and medical implications for such an ability are astounding. For example, this frog could help us cure a variety of stomach ailments such as ulcers and heartburn and may even provide new information on irritable bowl syndrome (IBS) and obesity.
If the female is unable to sustain herself during her pregnancy then does she die after the birth of her young? Is she ever able to reproduce again?
Usually I prefer to write to answer queries rather than leaving people more confused than when they first started reading. However, the gastric brooding frog has given me little choice. I can not answer the many questions surrounding this species because it is now believed to be extinct. It is incredibly sad when a species vanishes off the face of the earth. The gastric brooding frog I believe represents much of the plight of our natural world. It is an animal wrapped in mystery and simply confounds science by its very existence. We will never learn more of it and we will never understand how it was ever able to be. Every time a species goes extinct we may as well be burning books. We are losing something fantastic and unique from our world. Something may never be known or thought be drawn to it. The gastric brooding frog reminds us that this world is remarkable and we should be doing all we are able to save it.