Chameleons have "zygodactyl feet" (toes grouped in opposition to each other), which are a perfect adaptation for life in trees. Chameleons do not change colour to match the colour surrounding them. The reason for colour changes in chameleons is often in response to emotional changes, or to communicate with other chameleons. Different colours and patterns indicate different messages: happy/content, food/hungry, tired/sleep, alert/uncertain, stressed etc. Chameleons have very poor hearing, they also have no sense of smell. Despite this, they do have excellent vision.