Taxonomy
A scanning electron micrograph showing the diffraction grating on a single hair of Azygocypridina lowryi with a ridge spacing of 600nm. © A Parker
Among ostracods, Azygocypridina lowryi has a unique lateral eye, consisting of a triangular flap with some photo-pigment and some hairs. This eye cannot form images, however, but rather detects the intensity of light falling upon it.
Azygocypridina lowryi could be considered a “living fossil” since some other members of the genus Azygocypridina, appearing near identical to Azygocypridina lowryi, are known from Cretaceous fossils, 145-65 million years old. In the evolutionary tree of the ostracod family Cypridinidae, the genus Azygocypridina appears at its base, in this case suggesting that Azygocypridina is actually around 350 million years old.
Hairs on the first antennae of Azygocypridina lowryi show spectacular iridescence due to diffraction gratings, like those found on a CD or in holograms on credit cards. This varies from violet to red, as the eye moves around the antenna. In more derived species of Cypridinidae, where this iridescence is far more pronounced in males than in females, it is used as a courtship display. However, its function in Azygocypridina lowryi is unknown.