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Invisible message

When stimulated with ultraviolet light, the cock-eyed squid (Histioteuthis sp.) becomes covered with bright red dots. The experiment was carried out aboard the University of São Paulo (USP) research vessel Alpha Crucis, and it is not yet known what the results tell us about the animal, which lives at depths of between 200 and 1,000 meters. Sunlight only reaches these depths in shades of indigo, and the vision of animals that live there is usually limited to that color. The red spots, possibly produced and seen only by these squid, could work like the invisible ink used in spy games, decipherable only to those who know the secret of how to decode it.

Image submitted by biologist Marcelo Souto de Melo, from USP’s Oceanography Institute and recognized by the photography competition celebrating 20 years of FAPESP’s Biota Program