[HPsquared]

See also magnetic sensing (magnetoreception) in animals used for orientation and navigation.

https://en.wikipedia.org/wiki/Magnetoreception

There are other electromagnetic type things too, like use of light (camouflage, bioluminescence, eyes) and electricity (electric eels, bioelectrical cues for stem cell differentiation).

EDIT: Also the literal electrical potential within cells: the membrane potential, that is the voltage difference between inside and outside every cell.

An interesting area!