Dragonfly question

[Lesinlondon]

Why do dragonflies rapidly twist their head clockwise and/or anti-clockwise? I'm assuming it's to get an all round view of their surroundings, maybe scanning for prey or intruders? Normal view coverage must be pretty wide anyway.

I have been trying to get a pic of this recently - but too rapid for me (so far), so here's a Common Darter (Sympetrum striolatum) being uncooperative yesterday.

[RoyW]

Although the eyes are large, and there is some degree of vision over a large field of view, there is evidence from the structure of the eyes that the best vision is more restricted.
Changing the viewing angle no doubt helps the dragonfly to get a better picture of what's around.

[Lesinlondon]

Thanks Roy, I guess it has to be the reason. Those I have seen recently seemed to do this more frequently when there were Emperor's about, or on my approach, though they settled down once they became used to my prescence - hence no pics.

I never previously gave a thought to the size of Common Darters, all I have seen being about the same size, but today there was an abundance of young about, and these were only around two inches. Anyway, thanks. Les.