Evidence toads may modulate landing preparation without predicting impact time

Abstract

Within anurans (frogs and toads), cane toads (Bufo marinus) perform particularly controlled landings in which the forelimbs are exclusively used to decelerate and stabilize the body after impact. Here we explore how toads achieve dynamic stability across a wide range of landing conditions. Specifically, we suggest that torques during landing could be reduced by aligning forelimbs with the body's instantaneous velocity vector at impact (impact angle). To test whether toad forelimb orientation varies with landing conditions, we used high-speed video to collect forelimb and body kinematic data from six animals hopping off platforms of different heights (0, 5 and 9 cm). We found that toads do align forelimbs with the impact angle. Further, toads align forelimbs with the instantaneous velocity vector well before landing and then track its changes until touchdown. This suggests that toads may be prepared to land well before they hit the ground rather than preparing for impact at a specific moment, and that they may use a motor control strategy that allows them to perform controlled landings without the need to predict impact time.

Cooperation behavior of fore‐ And hindlimbs during jumping in Rana dybowskii and Xenopus laevis

“…Generally, frogs’ jump can be divided into four phases: preparation, takeoff, flight, and landing. The first phase begins with a crouched stationary position, preparing for the takeoff phase; the takeoff phase of jumping involves rapid hindlimbs extension accompanied by loss of forelimbs contact; the flight phase is characterized by midair body and limbs rotations in preparation for landing; landing begins when forelimbs or body touch the ground, and then, the flexed hindlimbs rotate into position beneath the body, enabling the rapid preparation of another takeoff (Azizi et al., 2014; Cox & Gillis., 2016, 2017, 2020). To escape from external danger optimally, all phases should be in short duration.…”