A frog: their eyes can detect a single photon of light | Helen Sullivan

Some species of frog have eyes so sensitive to light that they can detect a single photon.

Scientists dissected a frog’s eye and removed the lens.

A frog in space, moving further and further from the sun, would eventually start to see not a shrinking star, but tiny flashes of light: individual photons.

This is because as the photons travel further from their source, they are spread over greater areas.