What is the tapetum?

What is the tapetum?

• A. A nerve fiber layer behind the retina
• B. A pigment layer behind the retina
• C. A reflective layer behind the retina in some nocturnal mammals that enhances night vision
• D. A layer that absorbs stray light

Answer: (C)

The tapetum lucidum is a reflective layer behind the retina found in many nocturnal mammals. Its job is to reflect light that has already passed through the retina back through it, giving photoreceptors a second chance to absorb those photons. This increases visual sensitivity in very dim light and is the reason eyes can appear to shine when illuminated at night. It’s not a nerve fiber layer, nor the pigment layer that sits behind the retina to absorb stray light; that pigment layer helps absorb stray light to reduce glare and scattering rather than reflect it.

The tapetum lucidum is a reflective layer behind the retina found in many nocturnal mammals. Its job is to reflect light that has already passed through the retina back through it, giving photoreceptors a second chance to absorb those photons. This increases visual sensitivity in very dim light and is the reason eyes can appear to shine when illuminated at night. It’s not a nerve fiber layer, nor the pigment layer that sits behind the retina to absorb stray light; that pigment layer helps absorb stray light to reduce glare and scattering rather than reflect it.