Which structure in animals is thought to enhance vision in dim light?

The tapetum lucidum is a structure found in the eyes of many animals, particularly those that are nocturnal, which enhances their ability to see in dim light conditions. This reflective layer of cells is located behind the retina and works by reflecting light that passes through the retina back into the eye, providing a second chance for photoreceptor cells (cones and rods) to absorb light. This results in increased light availability for vision, making it particularly advantageous for hunting at night or in low-light environments.

In contrast, the cornea, ciliary body, and limbus have different functions related to eye anatomy and vision. The cornea is responsible for focusing light and providing the primary refractive power of the eye. The ciliary body primarily controls the shape of the lens for focusing and produces aqueous humor, while the limbus acts as a boundary between the cornea and the sclera and plays a role in the nourishment of the cornea and the regeneration of corneal cells. None of these structures contribute to enhanced vision in low-light conditions to the extent that the tapetum lucidum does.