© 2021. Published by The Company of Biologists Ltd | Journal of Experimental Biology (2021) 224, jeb242685. doi:10.1242/jeb.242685 INSIDE JEB Italian agile frog tadpoles can learn to evade crayfish terror scrutinised the movies, they found the tadpoles were afraid of the fed dragonfly larvae, freezing ∼80% of the time, while the fasted dragonfly larvae were almost as terrifying for the tadpoles. And when the youngsters did move after catching a whiff of their predator, they wove around more, in a bid to throw off the hunters, and switched course in all directions, to keep an eye out all around. However, the tadpoles were less savvy when Gazzola added eau de crayfish to their water. Only the tadpoles retrieved from a pond where crayfish reside showed any sign of toning down their activity to evade detection. The tadpoles from ponds A 25 day old Italian agile frog (Rana latastei) tadpole. Photo credit: Giovanni Scribano. with few or no crayfish didn’t alter their behaviour much, as if they didn’thavea care in the world. However, when An invader prowls the ponds and rivers of Collecting both predators from nearby Gazzola added a dash of water from the Northern Italy, taking out locals and waterways, Andrea Gazzola fed them on container of fed crayfish to the threatening entire species; can they fight Italian agile frog tadpoles, to make sure youngsters’ home, the developing ’ back? This is not a Hollywood movie; it s that they reeked of danger; predators amphibians became more wary. Even the happening right now in the gentle streams release the alarming aroma of their tadpoles that did not share their home of Lombardy and the chief intruders are dismembered victims in their vicinity. ponds with crayfish were slightly more ‘ alien red swamp crayfish. This highly Then, Pellitteri-Rosa retrieved freshly laid cautious, but less so than the youngsters … invasive and voracious predator can Italian agile frog frogspawn from ponds in from ponds where crayfish had already have dramatic impacts on freshwater three nearby areas, taking them to the lab taken up residence. fauna and alter aquatic ecosystems’,says to find out whether the stench of feasting Daniele Pellitteri-Rosa from the dragonfly larvae would affect when the It seems that Italian agile frog tadpoles University of Pavia, Italy. The crayfish tiny frog embryos emerged from their can learn to evade alien predators, have already devastated one local species: eggs. But it did not. The tiny embryos probably by learning to associate the scent Rana latastei the Italian agile frog ( ). But were unable to alter when they hatched to of devoured tadpoles with the invader’s hope for this threatened species could lie evade danger. So, how would the aroma. But Pellitteri-Rosa and colleagues in the form of the next generation. If youngsters fare in later life when faced are anxious that time might be stacked embryos in frogspawn can sense a lurking with peril? against survival for species that are threat, they may be able to alter when they already teetering on the brink. hatch to stand a better chance of survival. Filming 15 day old tadpoles swimming in Alternatively, tadpoles might be able to a cup, Gazzola then infused 2 ml of water 10.1242/jeb.242685 improve their odds by taking evasive carrying the odour either of unfed action when danger looms. Pellitteri-Rosa predators or of predators that had recently Gazzola, A., Balestrieri, A., Scribano, G., and colleagues decided to find out how dined on tadpoles, while continuing to Fontana, A. and Pellitteri-Rosa, D. (2021). Contextual behavioural plasticity in Italian agile Italian agile frog embryos and tadpoles record the tadpoles’ reactions. Sure frog (Rana latastei) tadpoles exposed to native respond to local predators – such as enough, when Giovanni Scribano and and alien predator cues. J. Exp. Biol. 224, dragonfly larvae, which they always Alessandro Balestrieri (University of jeb240465. doi:10.1242/jeb.240465 reside alongside – and the crayfish Pavia) and Andrea Fontana (Istituto Kathryn Knight invaders that threaten their future. Nazionale di Fisica Nucleare, Italy) [email protected] Inside JEB highlights the key developments in Journal of Experimental Biology. Written by science journalists, each short report gives the inside view of the science in JEB. Journal of Experimental Biology 1.