|Copyright: Miguel Angel Menegotto (miguel5526) (107)|
|Date Taken: 2010-01-02|
|Exposure: f/8, 1/500 seconds|
|More Photo Info: [view]|
|Photo Version: Original Version|
|Date Submitted: 2014-05-16 3:01|
|[Note Guidelines] Photographer's Note [Spanish]|
|The life cycle of dragonflies from the egg stage to death in adulthood, spanning six months to six or seven years. Female dragonflies lay eggs in or near water , often on floating or emergent plants . When some species are laying eggs in the water , submerge completely in order to lay their eggs on a good surface . Sometimes , females lay eggs in small cracks in the mud or moss. The eggs hatch into nymphs . While they are in the nymphal stage feed on mosquito larvae. Most of the life of a dragonfly spent nymph shaped , below the water surface , using extensible jaws to capture other vertebrates and invertebrates or even fish tadpoles . They breathe through gills in their rectum, and can rapidly propel through the water that suddenly ejected by ano.Algunas nymphs hunt on land , an ability that could easily have been more common in ancient times when terrestrial predators were clumsier .|
The larval stage of large dragonflies may last up to five years. In smaller species , this stage may last between two months and three years. When the larva is ready to metamorphose into an adult , it climbs up a reed or emerging plant . Exposure to air causes the larva to begin breathing. The skin splits at a weak spot behind the head and the adult dragonfly crawls out of its old larval skin , moves its wings up and down, and flies to feed on mosquitoes and flies. In flight the adult dragonfly can propel in six directions : up, down, forward, backward and side to side. The adult stage ( flying ) of the larger species of dragonfly can last up to five or six months.
In the distant past there were much larger species. The largest , found as a fossil , is a call Protodonata Meganeura monyi dating from the Carboniferous with a wingspan of 70-75 cm. The largest species of modern odonatas , the Anax strenuus , endemic to Hawaii, and the giant Central America, Megaloprepus coerulatus have 19 cm wingspan . The smallest modern species recorded is Nannophya pygmaea , in Asia, with a wingspan of only 20 mm.
The common dragonfly, Anax junius , is one of the largest and faster and can reach a speed of 85 km per hour.
Source : Wikipedia
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