Dragonfly nymph 3rd Instar Aeshna palmata - dorsal view

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svalley
Posts: 343
Joined: Sun Dec 03, 2006 7:07 pm
Location: Albany, Oregon

Dragonfly nymph 3rd Instar Aeshna palmata - dorsal view

Post by svalley »

A dorsal view of a 3rd instar nymph of the dragonfly Aeshna palmata. This is the same nymph that was shown in http://www.photomacrography.net/forum/v ... hp?t=36700

Note the tubercle behind each eye. In the 3rd instar it has gained another spine. There is some speculation that it may have a sensory function to make up for the lack of well developed eyesight in the early instars.

Image

A 100% crop of the tubercle.

Image

Shot with a Nikon D810, Mitutoyo 20x M Plan mounted on a Micro-Nikkor 200mm, Flash (transmitted light), ISO 64, f5, 207 frames stacked with Zerene PMax.
"You can't build a time machine without weird optics"
Steve Valley - Albany, Oregon

MarkSturtevant
Posts: 1946
Joined: Sat Nov 21, 2015 6:52 pm
Location: Michigan, U.S.A.
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Post by MarkSturtevant »

Interesting sensory hairs on those tubercles behind the eyes. They are against a projection of cuticle, which I suppose means they can't be bent backwards.
Living in dimly lit water, I suppose it would be useful to have sensory projections to help the critter navigate past obstructions. Kind of like whiskers on a nocturnal mammal.
Mark Sturtevant
Dept. of Still Waters

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