What is the primary function of the photophores located on the underside of the Viper Shark?

Answer

Counterillumination

The photophores found along the ventral surface of the Viper Shark serve the purpose of counterillumination. In the dim, downwelling light of the bathypelagic zone, these light-producing organs allow the shark to match the ambient light conditions, thereby erasing its own silhouette and rendering it invisible to potential predators looking upward from below.

What is the primary function of the photophores located on the underside of the Viper Shark?
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