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Japanese Giant Salamanders win "Dad of the Year"

     Unfortunately animal dads frequently get a bad rap. The male of the species is often the "lone wolf" type, who does not live with the females or take part in the raising of young. Of course there are several exceptions to this. One particularly interesting one comes from an underwater habitat in Japan.

Japanese giant salamander (Y. de Hoev.  Public domain, via Wikimedia Commons)
The Japanese giant salamander is a humongous amphibian. This ancient salamander can grow up to 5 ft long! The largest of the males of the species take up residence in freshwater dens. These "den-masters" create burrows and maintain the dens, which are only accessible to females. Females visit the den to mate and lay eggs, then they leave. The male salamanders stay to care for the eggs. Scientists recently identified three specific behaviors that the salamander dads exhibited when caring for their young. Their research was published in the Journal of Ethology. The three behaviors were: tail fanning, agitating and egg eating. The latter two might not sound like positive behaviors in the care of fragile eggs, but they do indeed have beneficial results.
     The salamander dads fan their tails over the eggs to oxygenate the water surrounding the eggs. Researchers found that in artificial den situations with lower oxygen levels the salamanders fanned their tails more vigorously to make up for the low oxygen conditions. The salamanders moved, or agitated the eggs with their heads and bodies. Researchers believe this prevents yolk from sticking to the sides of the eggs and causing the salamander embryos to develop incorrectly. Lastly, the male salamanders ate some of the eggs. It is not uncommon for males, and even females, to be egg cannibals. However, in this case the salamander dads only seemed to munch eggs that were cloudy and most likely dead, unfertilized or moldy. It is thought that this protects the other eggs from infection.
Japanese giant salamander pair (photo by V31S70)
     It may be possible that the Japanese giant salamander has relatives, such as the hellbender and the Chinese giant salamander,  that exhibit similar paternal behaviors. These new details may help in conservation efforts to save dwindling populations of the Japanese giant salamander. Population numbers have dropped due to habitat loss and hunting.






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