Fig. 5

The very unusual apposition compound eyes of stomatopod crustaceans or mantis shrimps. Panel a shows the tall eye of Lysiosquillina maculata, while Panel b illustrates the more spherically shaped eye of Odontodactylus scyllarus. In both species, the eye is formed from three functional arrays of ommatidia: the dorsal and ventral hemisphere arrays, and the midband array, formed from six parallel rows of ommatidia. See the text for an explanation of how these very unusual eyes function in vision. The tall eye is well adapted for flat-world environments (much like the fiddler crab eye illustrated in Fig. 4d–e), while the spherical eye is adapted to a more complex visual environment, such as might be found in a rubble field or on a coral reef. Note the dark patches visible on parts of these eyes (particularly the right eye of L. maculata). These indicate the patches of ommatidia that receive light from the direction of the camera, and are called ‘pseudopupils’. The presence of three pseudopupils in a single eye shows how the eye views a single point in space from three independent patches of ommatidia. Photographs by R.L. Caldwell