Anuran tadpoles experience intense predation pressure during their aquatic larval stages. Over evolutionary time, numerous anti-predator strategies have emerged, including camouflage, chemical defenses, behavioral adaptations, and increased swimming speed. In the event of an attack, however, one of the most remarkable adaptations is the ability to regenerate injured tails. This regenerative ability, while beneficial, can come at the cost of reduced survival or future reproductive success.

A 2022 study published in Amphibian Herpetology (AH) investigated how tail injury affects survival and feeding behavior in Dendropsophus elegans, a neotropical treefrog native to Brazil’s Atlantic Rainforest. Egg clutches collected in the wild were reared under controlled laboratory conditions. Once tadpoles reached 25 mm in length, they were assigned to four experimental groups with different degrees of tail clipping (30%, 50%, 70%, and a control group with intact tails). Researchers measured time to metamorphosis, snout–vent length (SVL), and weight at metamorphosis. Additionally, feeding activity was compared between the control group and the group with 70% tail loss.

Tail regeneration occurred in all individuals within 12 days. Interestingly, the extent of tail clipping did not affect SVL or weight at metamorphosis. However, tadpoles with more severe tail injuries took significantly longer to reach metamorphosis. This response contrasts with that of other anuran species, in which tail injury often results in smaller or less developed individuals without affecting development time—making them more vulnerable to terrestrial predators post-metamorphosis.

Notably, severely injured tadpoles did not show an increase in feeding frequency, indicating that energy for tail regeneration is drawn from existing reserves rather than increased intake. This suggests a reallocation of energy toward tissue repair at the expense of growth.

The extended larval period observed in injured D. elegans is not without cost. A prolonged aquatic phase increases exposure to aquatic predators and may delay reproductive maturity after metamorphosis.

Read the full paper here.

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