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Why do snakes that locate warm prey with infrared radiation not use photoreceptors for that task?

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details of the mammalian eye — Photoreception The mammalian eye has a cornea and a lens and functions as a dioptric system, in which light rays are refracted to focus on the retina.

Snakes that locate warm prey using infrared radiation do not rely on photoreceptors for this task because they possess specialized, distinct heat-sensing organs known as pit organs.21

These organs, found in pit vipers, boas, and pythons, are anatomically and functionally adapted to detect infrared radiation rather than visible light. The pit organs contain a thin, densely innervated membrane supplied with nerve fiber endings that respond specifically to thermal energy. Unlike the retina in the eye, which is specialized for light detection, these receptors are highly sensitive to rapid changes in temperature, allowing the snake to detect the heat radiated by warm-blooded prey even in total darkness.213

By utilizing these dedicated thermoreceptors, these snakes can accurately localize and strike at prey based on thermal signatures, a process that is distinct from the visual processing performed by their eyes.21