“Amphioxus point of view”

Light, a crucial environmental signal, that drives lives of myriad creatures upon the Earth, regulating processes such as circadian rhythms, reproductive cycles, and visually guided behaviors. We all perceive light through specialized cells called photoreceptors. Behold Amphioxus, who possesses several distinct types of photoreceptors. It is also considered one of the closest living likenesses to the last common ancestor of all vertebrates. Although it lacks many vertebrate-specific innovations, it has a simple body plan and homologous structures shared with vertebrates. In this discourse, we shall cast our gaze more narrowly upon these photoreceptors of Amphioxus, to unravel their function and inquire whether they may reveal some glimmer of the origins whence the vertebrate visual systems first took its light.