Proc. R. Soc. B doi:10.1098/rspb.2009.2248 (2010)

Credit: R. SOC.

Box jellyfish (Cubomedusae) have a complex system of 24 eyes that comprises pits, slits and two types of lens (a set of six eyes is pictured). But whether they can perceive colour has been a matter of debate.

Now, Megan O'Connor of Lund University in Sweden and her colleagues have identified the visual pigment present in the lens eyes of the Chiropsella bronzie jellyfish. Using microspectrophotometry and antibodies for zebrafish visual pigments, they found just one type of pigment. For colour vision, two or more are necessary.