Magnetosensitivity of amphibian morphological pigmentation is light- and eye-dependent and consistent with the radical pair mechanism

Weak magnetic fields influence a wide range of biological processes, yet the underlying mechanisms are poorly understood.

The radical pair mechanism (RPM), which involves quantum spin dynamics, is a leading hypothesis.

Here we show that weak magnetic fields modulate morphological pigmentation -- specifically, the number of perioptic melanophores -- in Xenopus laevis tadpoles in a field-strength-dependent manner.

The response is light- and eye-dependent.

The observed field-strength dependence is quantitatively consistent with a radical pair model.

These properties are reminiscent of the light-dependent magnetoreception that is thought to operate in migratory birds, and establish amphibian pigmentation as a tractable vertebrate system for the study of radical-pair quantum biology.