Figure 1 (IMAGE) Institute for Basic Science Caption Structures and functions of bird’s eye. (a) Bird vision. (b) Deep central fovea and four types of cones. (c) Foveated vision and tetrachromatic vision. Credit Institute for Basic Science Usage Restrictions Attribution Required License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.