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Photo#207439
Pachydiplax longipennis? And Related Question - Pachydiplax longipennis - male

Pachydiplax longipennis? And Related Question - Pachydiplax longipennis - Male
Liberty, Missouri, USA
June 8, 2008
I think this is Blue Dasher, but I do have a question! This is probably something I should know, but I am going to ask anyway! In the photos, (you may have to enlarge it to see) but there's a hole/indentation type thing right behind his/her eyes and I am very curious as to what this is and what it's purpose might be??

Moved
Moved from Dragonflies.

Male Blue Dasher
Nice pic. Dragonflies' heads have to move almost 360 degrees in any direction, so I think the indentation allows greater freedom of movement. The actual point where the head attaches to the thorax is surprisingly small and pretty weak, sacrificing strength and sturdiness for flexibility. Very different from something like a beetle's head, which is usually firmly attached but has limited range of motion.

 
Thank you! Very interesting info!
When I got home and looked at the pic, I got more and more curious as to what that was for!

Thanks again!

 
Christina,
Take a look at this image for a little more detail of the head/neck area.

Eastern Pondhawk (Erythemis simplicicollis)

 
From that angle, on your example, it shows
clearly the connection of the head, which is very neat to see. On my photograph, even viewed large, it looks like a hole of some sort, and looks quite different. Is that because of the camera angle or what?

 
Camera angle is part of the difference...
The best example I can think of to illustrate how it work and what we are seeing in the two different angles would be to stick your fist in a mixing bowl. Your arm and fist being the body/neck and the bowl being the head. The head of the dragonfly is shaped like a bowl. this allows plenty of room for the head to move just like the bowl would move around your fist.

In my picture from straight down, the neck is partially blocking the view inside the bowl-shaped head. In you picture you are looking over it's neck and can see deeper into the head.

And the fact that they are different species with slightly different shaped body parts might make a little difference also...

 
Thanks for the info!
I love learning more about these guys. I never stopped to pay attention to the way their heads are designed, until I took this photo. It's very interesting and amazing. Thanks for sharing your great photo and for answering my question!

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