The tapetum lucidum of many vertebrates enhances night vision by reflecting light back to photoreceptors in the eye.

“The tapetum lucidum is a biologic reflector system that is a common
feature in the eyes of vertebrates. It normally functions to provide
the light-sensitive retinal cells with a second opportunity for
photon-photoreceptor stimulation, thereby enhancing visual sensitivity
at low light levels…

“Some species (primates,
squirrels, birds, red kangaroo and pig) do not have this structure and
they usually are diurnal animals. In vertebrates, the tapetum lucidum
exhibits diverse structure, organization and composition. Therefore,
the retinal tapetum (teleosts, crocodilians, marsupials, fruit bat),
the choroidal guanine tapetum (elasmobranchs), the choroidal tapetum
cellulosum (carnivores, rodents, cetacea), and the choroidal tapetum
fibrosum (cow, sheep, goat, horse) are described…

“The tapetum lucidum
represents a remarkable example of neural cell and tissue
specialization as an to a dim light environment and, despite
these differences, all tapetal variants act to increase retinal
sensitivity by reflecting light back through the photoreceptor layer.
These variations regarding both its location and structure, as well as
the choice of reflective material, may represent selective visual
adaptations associated with their feeding behavior, in response to the
use of specific wavelengths and amount of reflectance required.” (Ollivier et al. 2004:11)

Last Updated October 26, 2016