Posts Tagged ‘cast skin’

Emerging Common Sanddragons

June 29, 2014

Two emerging Common Sanddragon dragonflies (Progomphus obscurus) were spotted on 15 June 2014 during the “Advanced Dragonfly Studies” adult class and field trip to the Patuxent Research Refuge. The field trip was led by Richard Orr, renowned expert on odonates of the mid-Atlantic region, and Stephanie Mason, Senior Naturalist, Audubon Naturalist Society.

emerge: to leave water and undergo metamorphosis into an adult; emergence is thus both from water and from exuvia Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 11593-11594). Princeton University Press. Kindle Edition.

The first two photos show a sanddragon emerging from its exuvia (plural exuviae), also known as a “cast skin.” Notice that its wings have not started expanding.

Common Sanddragon dragonfly (emerging, teneral, exuvia)

Common Sanddragon dragonfly (teneral, exuvia)

The wings, folded like accordions, then begin to fill from the base with fluid transferred from the body and fairly soon reach full length. The fluid is then pumped back into the abdomen, and it expands. Finally, the wings open up, and very soon the teneral adult flies away. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 466-468). Princeton University Press. Kindle Edition.

The last photo shows a teneral adult (upper right) and its exuvia (lower left). Since it takes approximately 30 minutes for dragonfly wings to expand, we can infer this sanddragon emerged before the other one.

Common Sanddragon dragonfly (teneral, exuvia)

Copyright © 2014 Walter Sanford. All rights reserved.


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