Swallow the young for them to grow?

Figure 1: A tiny froglet emerging from its mother's mouth

Figure 1: A tiny froglet emerging from its mother's mouth

Isn’t amazing to see a froglet coming out of a tiny mama frogs’ mouth? It intrigued me to find out more about this mini frog. It has the common names known as “Gastric brooding frog” or “Platypus frogs” which were a genus of ground-dwelling frogs native to Australia. This genus was unique as it consisted of only two species, Southern Gastric brooding Frog (Rheobatrachus silus) and Northern Gastric brooding Frog (Rheobatrachus vitellinus), that breed the young frogs in the stomach of the mother and give birth through mouth.

From the photo, you can see how small the mother frog is compared to human finger. Hence, why do they have such a unique reproductive method?  Before Gastric brooding females swallow the fertilized eggs, females give up eating and drinking for those six weeks so as to reserve the stomach merely for the tadpoles. The developments of tadpoles take place in female’s stomach. Initially, scientists were puzzled by how the females manage to “switch off” the secretion of digestive fluids (hydrochloric acid) during brooding. From the research, they found out that the tadpoles produce hormones which cause the female to cease the production of digestive fluids. It protects them from being digested in the stomach of the mother.

The development manner of tadpoles in the stomach is same as the aquatic tadpoles of other species as they all feed off egg yolk, the labial teeth are absent and the intestines form at a later stage of development. However, where do the tadpoles in the stomach get the egg yolk? The eggs are significantly larger than the eggs of the other species which contain a yolk rich in proteins, adequate to feed the tadpoles for the entire period of development. Hence, after 6-7 weeks the females can give birth to up to 25 young, birth is done by the female widely opening her mouth and dilating her gullet (esophagus). The froglets are propelled from the stomach to the mouth, and then jump away, at intervals over a period of several days (Tyler and Carter, 1981).

The unique reproduction of Gastric Brooding Frogs which is also known as exclusive form of parental care makes them to be so special among vertebrates. However, this species is currently listed as Extinct by the International Union for the Conservation of Nature. No individuals have been observed in the wild since 1981, despite extensive searches. It is a sad thing to know about it.

References:

Image:

“Rheobatrachus silus — Southern Gastric Brooding Frog with baby in its mouth,” by D. Sarille. Save The Frogs, 20 April 2008. URL: http://www.savethefrogs.com/gallery/v/Extinct_Amphibians/Rheobatrachus_silus_with_baby.html (accessed on 5 April 2010).

Article:

“Rheobatrachus silus,” by Semeyn, E. 2002.Hosted on Animal Diversity Web: http://animaldiversity.ummz.umich.edu/site/accounts/information/Rheobatrachus_silus.html (accessed on 6 April 2010).

 

“Gastric Brooding Frog,” URL: http://www.global-greenhouse-warming.com/gastric-brooding-frog.html (accessed on 5 April 2010).

Journals:

Tyler, M.J. & D.B. Carter, 1981. Oral birth of the young of the gastric-brooding frog Rheobatrachus silus. Animal Behaviour, 29(1):280-282.

Corben, C. J., Ingram, G.J., & Tyler, M.J., 6 Dec1974. Gastric Brooding: Unique Form of Parental Care in an Australian Frog. Science, New Series, 186(4167): 946-947

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