Diodon holocanthus – The Gleaming Eye

The eye of Diodon holocanthus is one of its most striking features. Large and round, it provides excellent vision in the dim light of reef crevices where this nocturnal species often hides during the day. The eye has a reflective layer called the tapetum lucidum, which enhances its ability to see in low light by reflecting light back through the retina. This gives the eye a characteristic shine when illuminated at night. The dark iris contrasts with the silvery-blue ring of the cornea, contributing to the porcupinefish’s distinctive appearance and helping it detect predators and prey in its environment.