Many shark species can see colors, helping them hunt in the deep blue ocean.

Marine biologists previously believed sharks were monochromatic, but recent studies have identified cone photoreceptors in several species. Research published in the journal 'Naturwissenschaften' by Dr. Nathan Hart and his team at the University of Queensland used microspectrophotometry to examine shark retinas. They found that while some species like the bull shark may be colorblind, others like the great white and hammerhead possess the biological hardware for color vision.The ability to see color is highly dependent on the shark's habitat and depth. In the upper 200 meters of the ocean, known as the epipelagic zone, sunlight provides enough spectrum for color detection. However, as depth increases, water acts as a filter that absorbs longer wavelengths like red and orange first. This leaves only shorter wavelengths, specifically blues and greens, to penetrate deeper into the water column.To adapt to these conditions, many sharks have evolved a 'tapetum lucidum,' a reflective layer behind the retina. This structure reflects light back through the retina a second time, significantly increasing their sensitivity in low-light environments. This evolutionary trait makes shark eyes roughly ten times more efficient than human eyes at capturing photons. By combining this sensitivity with the ability to distinguish blue-green contrasts, sharks can easily spot the silhouettes of prey against the ocean's background.