The eyes of visually competent animals such as vertebrates, insects and cephalopods serve many visual tasks, and are involved in controlling a large part of the behaviour in these animals. But when the first eyes originated more than 500 million year ago, it is unlikely that they started out as the multi-purpose organs we see today. Rather, the first eyes are expected to have been simple organs originally serving a single task. As evolution went on, new and more complex visual tasks have been added, one after the other, leading to the multi-purpose eyes we see today in many animals.
If we are going to understand how eyes first originated we must work out what the first visual tasks were, and what requirements these placed on eye structure and physiology. Luckily there are still many primitive animals around that can tell us what the first visual tasks were. We investigate a handful of primitive animals, but have focused mostly on Box Jellyfish. Here we study visual behaviour, eye structure, visual physiology, neuroanatomy and information processing in the nervous system. Our results so far indicate that vision is used solely for maintaining the animals in a suitable habitat.