Sunday, May 19, 2013

Necrophilic Frog Rhinella proboscidea

Sex is an important aspect of evolution. But exactly how important is it? Well, for a small Amazonian frog called Rhinella proboscidea, to the point of copulating with a dead partner. 

But wait, it goes beyond mere necrophilia.
Rhinella proboscidea. Image:
Necrophilia is pretty rampant in the animal kingdom. British Antarctic explorer George Murray Levick observed a male Adelie penguin trying to have sex with a dead female during his expedition of 1910-1913. IgNobel laureate C.W Moeliker won his IgNobel for documenting the first scientifically recorded case of homosexual necrophilia in mallard ducks.
A lot of male creatures sacrifice themselves for reproduction, most notably insects like praying mantis and spiders. But in the case of R. proboscidea, it's the female that has to bear the cost of mating.
The males form huge mating balls so heavy around a single female to the point where the female sometimes drowns. Undeterred, the males would then rhythmically press the sides of the belly of the dead female to extract the eggs, which would be then fertilized. That's a combination of necrophilia plus mutilation. Eww...
A male R. proboscidea with a dead female. Image:
Thiago Izzo from Brazil’s National Institute of Amazonian Research, who has seen and reported the case, calls it “functional necrophilia”. He kept an eye on the eggs and saw that they eventually developed into embryos.

Frankly, I can't see any benefit for the species because with this strategy, each female would have only one chance of passing on her genes, unlike other less "violent" species where the females could lay different batch of eggs.
Perhaps some other researcher can come up with a better idea?


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