Like a Fish out of Water: Temporary Habitat Switching Detected in Aquatic Tadpoles Resting Above the Water's Surface

Amphibian tadpoles are typically aquatic and constrained to freshwater throughout development. These circumstances change at metamorphosis, whereupon individuals may complete a partial or full habitat shift towards terrestriality and gain the capacity to transition between habitat types. In this study, we present evidence of striped marsh frog tadpoles, Limnodynastes peronii, resting out of the water on floating vegetation mats in freshwater ponds, despite being fully aquatic and at a developmental stage far proceeding metamorphosis. We propose that this behaviour may represent a form of adaptive beaching to obtain survival benefits that are derived from being out of the water column. In particular, this may be a behavioural tactic of habitat switching to avoid aquatic predators, such as the introduced mosquitofish, Gambusia holbrooki, or to access oxygen from the air when the water becomes hypoxic. The capacity for aquatic tadpoles to exploit temporary refuges outside the water challenges traditional assumptions about their strict dependence on being continuously submerged below the surface for survival. While our findings are preliminary and based on a small sample size, they suggest the aquatic tadpoles of our focal species and perhaps others are not as restricted to their natal waterbodies as previously thought and that they have the capacity to move into habitats above the water's surface for resource gain.