Friday, January 9, 2009

Long Long Eyes : For vision and fighting.
Just imagine our range of vision if we had our eyes at the end of long stalks like this stalk eyed fly. These flies use thes telescopie eyes to see, to fight and even to attract maximum females towards them. This Stalk-eyed fly is insect of the dipteran family. The family is distinguished by the possession of eyestalks: projections from the sides of the head with the eyes at the end. These species have bizarre head projections such as antlers, eyes that project out of the head, or eyes that are on stalks. The exaggeration of eye-stalks can be extreme, with males having an eyespan greater than their body length. Stalk-eyed flies are up to a centimeter long and have a largely terrestrial habit. There are several hundred species in the family, with the greatest diversity found all over the world and especially in Asian and African countries. Adult Diopsids are typically found on low-lying vegetation in humid areas, often near streams and rivers, where they feed on fungi and bacteria on decaying vegetation. The larvae develop in rotting vegetation.
Many stalk-eyed flies exhibit sexual dimorphism for eyespan, with males having much greater eyespan than females, and this has evolved many times within the family. Members of dimorphic species tend to disperse in moist undergrowth and low vegetation during the day and roost together at night in nocturnal clusters on rootlets or leaves. In some species males compete with each other to control these nocturnal aggregation sites, by literally "eyeing each other up": rearing up, spreading their front legs alongside their eye stalks and trying to knock each other over. The powerful male with the longer eyestalks forces the other to back off. Always when there is a female fly present during battle, the winner will mate with her. After mating the male fly guards her, keeping other males away to ensure that her offspring will be his. They release a special breeding scent from glands, visible on the fly as a lump on the underside of his abdomen. Females prefer to roost and to mate more frequently with large eyespan males. In contrast to many other invertebrate species, the basis of female choice is clear and willing to experimental investigation. The winner takes control of rootlets where females aggregate. Most mating occurs at dawn the following morning, before individuals disperse for the day.
Yuwaraj Gurjar.

No comments:

Post a Comment