Nature: June 2008 Archive Page

Usually, cuttlefish eggs lie in an envelope full of black ink. But this clears as the embryos grow older, leaving them growing within translucent eggs. These unborn cuttlefish also have fully developed eyes. That leads the researchers to conclude that the cuttlefish embryos must peer through their eggs, and learn to recognise their prey, a behaviour which will help give them a head-start in life.