Can penguins (Spheniscidae) see in the ultraviolet spectrum?

It has been postulated that ultraviolet reflectance is important in mate choice in King Penguins Aptenodytes patagonicus , although not in other penguin species that do not have body parts that reflect UV light. However, this theory has been challenged. Here we aimed to determine the transmission of the ocular media in the large King Penguin as well as the smallest penguin, the Little Penguin Eudyptula minor , and a medium-sized penguin, the Gentoo Penguin Pygoscelis papua , to determine if the penguin eye is capable of seeing ultraviolet light. In all species the cornea absorbed the most damaging rays at 300 nm or below but it was the lens that predominantly determined the transmission of light between 300 and 400 nm. The lenses of a young King Penguin absorbed almost all light less than 370 nm and had 50% transmission at 406 nm, thus ultraviolet perception in the King Penguin is very limited. In contrast, 50% lenticular transmission was 329 nm in the Little Penguin and 367 nm in the Gentoo. Therefore, we suspect that ultraviolet light may be more important in the behaviour of smaller penguins than in the King Penguin, where it is unlikely to play a significant role.