Animal Vision: Gazing into the abyss

Dr Ilse Daly continues her series with a look at sight in the deepest reaches of the sea

Given that over 70% of our planet is covered in water, it is hardly a surprise that the oceans are the least explored corners of our world. Each excursion we make into the depths reveals strange new animals whose lives are almost unimaginably different from our own. In this article, I will highlight some of their weird and wonderful visual systems; nevermind outer space, aliens, it turns out, live right here on Earth.

The ocean is broadly divided into four zones: the sunlight zone (0-200m), the twilight zone (200-1,000m), the midnight zone (1,000-6,000m), and the sinisterly named abyssal zone (below 6,000m). As the names of these zones suggest, the deeper the water, the darker it gets. That is because light does not travel as well through water as it does through air.

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