Post-embryonic development of the lateral eye of <i>Cloeon</i> sp. (Ephemeroptera: Baetidae) as revealed by scanning electron microscopy

Abstract

Post-embryonic developmental patterns of the lateral eyes of both male and female Cloeon sp. are described and compared with each other morphometrically on the basis of scanning electron microscopy. In the larvae number of ommatidia, ommatidial size, and total corneal surface area of the eye increase towards the subimaginal moult. It is then that clear differences between males and females begin to occur: while further increases in the number of ommatidia are recorded from the lateral eye of subimago and imago females (accompanied by decreasing facet sizes and interommatidial angles), males show decreasing numbers of ommatidia and total corneal areas in their lateral eyes as they prepare to leave the water. Consequently, the lateral eyes of a female are larger than those of a male imago. It appears that the enormous development of the dorsal eyes of the males has occurred at the expense of the lateral eyes. In male as well as female lateral eyes two major facet shapes are encountered: squares with rounded corners which are predominantly found in the central and upward looking areas, and hexagons which are dominating the lateral and ventral-facing regions. The different roles of the lateral eyes in male and female baetid mayflies is discussed in relation to their flights and the intriguing idea is presented that females might choose males with the largest dorsal eyes.

Compound eyes of insects and crustaceans: Some examples that show there is still a lot of work left to be done

“…Turning to the corneal surface now, we find shallow and irregular microprotuberances like those seen in the pollen-feeding beetle (Xanthochroa luteipennis; Mishra & Meyer-Rochow, 2006b) and we may see distinct structures referred to as corneal nipples and microridges in numerous insect species (see below). When present at all, such structures seem to be restricted to the adult stages and in aquatic insects do not appear until metamorphosis into the terrestrial adults (Gupta et al, 2000). By covering their eyes' facets with nanostructured nipples or microridges, insects create a layer that acts as a broadband antireflection coating.…”

Spectral sensitivity transition in the compound eyes of a twilight-swarming mayfly and its visual ecological implications

“…Although remarkable changes in the anatomy of eyes throughout different life stages both for females and males have been shown in Cloeon sp. [16], spectral sensitivity of any mayfly eyes has been measured only in very few cases, and as far as we know, no larvae were measured. Hence, we also measured the spectral sensitivity of larvae.…”