This dragonfly is readily recognised
by the dark drown markings on a yellowish to yellowish-brown background
on the wings; the abdomen is dark-coloured. Widespread commonly found around
water.
These dragonflies hunt on the wing,
gathering in swarms when food is abundant and capturing flying insects
in their legs which have bristles that interlock to trap the prey. The
legs project forward so that the food can be easily moved to the mouth
in flight. A pair of large eyes covers most of the head, so that the animal
can see in all directions with only a slight turning of the head. Each
eye has thousands of individual lenses that give the dragonfly a mosaic
image of the world. Body length around 33mm, the wingspans around 100 mm.
The male and female fly in tandem,
the male using special structures at the end of its abdomen to hold the
female's head. While in flight, the female bends her abdomen so that its
end touches the middle of the male's body, picking up sperm. Then she straightens
up and they continue to fly in tandem as the female lays eggs on the surface
of the water.
The eggs hatch about a week later
and the larvae (called nymphs) live in the water, taking in oxygen from
the water through gills that project from their guts.The nymphs feeding
voraciously on small aquatic animals such as insect larvae and crustacea.
They grow rapidly, repeatedly outgrowing their exoskeletons that are cast
off by the process of moulting. Just prior to the final moult, the nymph
climbs a plant into the air. There it undergoes its final moult and metamorphoses
into a winged adult. Blood is pumped into the wing buds that soon expand
into the beautiful lacy wings.
The purpose of the wing markings
is unknown but a curious evolutionary convergence sees similar markings
on a distantly-related dragonfly from North America: Celithemis eponina.
Rhyothemis graphiptera is found along
the north and east coasts of Australia as well as Indonesia, Papua New
Guinea and New Caledonia.
References:
http://www.flickr.com/photos/25747229@N00/2232500624/
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