Tadpoles found to jump on backs of unknown adults to escape cannibalistic siblings

A pair of researchers, one with Vrije Universiteit Brussel and the other Trier University in Germany has found that splash-back poison frog tadpoles willingly seek out any adult that comes near them to escape their cannibalistic siblings. In their paper published in Journal of Zoology, Lisa Schulte and Michael Mayer describe their study of the tadpoles in a field laboratory they set up in northeastern Peru, what they found, and why they believe the tadpoles behave as they do.

Splash-back poison frog females lay their eggs, as the researchers note, in plants that rise above the water line. When the offspring hatch as tadpoles, they drop down into a small pool of water where they soon begin to turn on one another if they are not moved elsewhere. Normally, the father shows up and bends his backside down low to allow one or two of his offspring to climb aboard. He then makes his way to a different pool where the tadpoles are released. The father makes such trips until his little ones are dispersed. But, as the researchers also note, sometimes a father, for unknown reasons, chooses to ignore his offspring, leaving the tadpoles to begin eating one another until a single one is left. Sometimes, though, the research pair found, a frog who is not the father will make its way into the pool and the tadpoles will swim toward it hoping to hop aboard for transport elsewhere. To learn more about such behavior, the researchers collected multiple clutches of tadpoles and placed them in pools where they could be studied and filmed when fathers, other males, other females and even frogs of other species were introduced into the pool.

The researchers report that all of the tadpoles swam toward an adult regardless of its gender—even those of another species. Many of them attempted to hop on the back of the adult and two of them actually succeeded. They were not fooled by 3-D printed frogs, however; none of the tadpoles swam toward them. The researchers conclude that the tadpoles are more than willing to try to escape their siblings by almost any means necessary when their father fails to separate them.

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