An insect with 100 eyes has left scientists, well, surprised

Parasitic insects known as Strepsiptera are so named for their twisted wings, from the Greek word strepsi, meaning twisted or turned, and ptera, wings. But wings are not their only warped feature, as scientists have found out. Indeed, these creatures, which prey on other insects such as paper wasps, have freaky peepers as well.

BUG'S-EYE VIEW. Eyelets in Strepsiptera each process a chunk of visual information, as opposed to the single points registered by the facets in compound insect eyes. Individual retinae invert the separate chunks as shown above. In reality, though, there is most likely less overlap between them.

Most bugs sport what are known as compound eyes, made up of hundreds--and sometimes thousands--of lenses that each sample an individual point in the visual field. Strepsiptera, however, have fewer and larger lenses, dubbed eyelets, clustered on either side of their head. Whereas the fruit fly Drosophila melanogaster may have some 700 facets per eye, one Strepsiptera called Xenos peckii has only 50 eyelets. And 15 fruit-fly lenses would cover the same area as one of X. peckii's lenses.

RECONSTRUCTION of part of the Strepsipteran visual system shows several individual eyelet lenses (yellow), retinae (red) and receptor cells and lamina (blue), as well as the tissue between eyelets (green).

Given such differences, researchers long suspected that eyelets might actually process whole chunks of a visual scene, not just separate points. But they had no proof. How do you view the world through Strepsipteran glasses?

Recently, though, the theory has gained solid support from a series of optical and neuroanatomical studies. Postdoctoral researchers Elke Buschbeck and Birgit Ehmer, along with Professor Ron Hoy of Cornell University measured numerous properties of X. peckii's eyelets and visual centers in the brain, all of which suggest that eyelets are in fact image-forming. Their work, published in the November 4th issue of Science, shows that Strepsiptera eyes may most closely resemble those of trilobites, marine invertebrates that swarmed in the earth's oceans 590 to 410 million years ago.

FLUORESCENT STAIN highlights individual eyelets inside this scanning electron microscope of X. peckii's eyes.

Buschbeck and company first performed several optical measurements and found that, based on their plane of focus and spatial cutoff frequency, each eyelet should be able to resolve several thousand points in the bug's-eye view. Moreover, the light-gathering power per eyelet was at least 30 times greater than that of the individual facets in traditional compound eyes. Approximations of the eyelet's sensitivity also indicated that they captured enough light so that the 100-odd photoreceptors in their retinae might each resolve a single image point.

EYELET, shown in this microscope section from an X. peckii pupa, has a thick lens covering its retina.