story of the Eye--

"The fish Bathylychnops exilis has four eyes: one set to look up, and one set to look down; but at what? Nobody knows. The surface-feeding fish Anableps anableps can see clearly both in and out of the water. Mantis shrimps use polarised light to swap messages that no other animal can see. Even a kilometre below the sea’s surface there is, incredibly, still plenty of material my story could have drawn on, if only there were room. Bioluminescent photophores tattoo the sides of lanternfish, fang-toothed fish dangle lures baited with light-making bacteria, and one deep-water fish, Aristostomias, communicates with others by generating pulses of red light – a colour no other neighbouring species can see..."