InTecht Vodcast Pilot
Fresh from production, the first episode of our video podcast covers the topic of dragonflies. Insufficient funds and poor executive planning lead to the episode needing to be split into two parts. Part two will (not) be released soon!
InTecht Episode 1: Extras
The aforementioned lack of planning also meant that some interesting details were left out of the video. We'll cover them below.
Differentiated Eyes
You may have noticed that species in the order "Odonata" (the group that contains dragonflies and damselflies) usually have two colors on their eyes, which, for damselflies, makes their eyes look more like ours. This is because dragonflies and damselflies both have areas on their eyes where the "sight hexagons," called ommatidia, are different. For dragonflies, their eyes are separated into two regions: an upper "Dorsal" region and a lower "Ventral" region, creating that color difference between the top and bottom of the eyes. The ommatidia in the top Dorsal region are adapted to identify objects and prey against the bright blue sky, whereas the Ventral ommatidia are specialized to identify prey against the relatively darker backdrop of the ground.
For damselflies, in addition to the top and bottom differentiation, they have an additional area that manifests as a dot at the front of their eyes, looking much like a pupil. It's theorized (or, rather, I theorize, since, as far as I know, this isn't backed up by any research) that this difference may have come about because of the slight differences in the hunting behavior of damselflies and dragonflies. Whereas dragonflies tend to perch in more open areas, damselflies tend to hunt while hiding amongst vegetation, and, as such, may make increased use of the front of their eyes.
Optical Differences
In addition to the eye regions mentioned prior, dragonflies and damselflies also differ in how their brains perceive sight. Scientific research has shown that, at least in species with eyes that touch at the top of their heads, dragonflies lack depth perception, process sight much like a computer with two monitors; objects can be seen on one eye or the other, but not both at the same time. Damselflies, on the other hand, can, allowing them depth perception. It's been theorized (this time, by actual researchers) that this is also because of the hunting differences; determining an object's exact distance would prove far more useful when hunting in vegetation with many obstacles than if you were in an open area, where you can essentially just book it towards the target.
My mom taught me to always cite my sources when I want to: Science Direct
Physical Differences
Now, we're starting to encroach on content that would have been covered in "Dragonflies: Part 2," but, it's fine, I wasn't really going to make it anyway.
One of the more noticeable differences, is that dragonflies spread their wings out to the side at rest, whereas damselflies hold them together, above their body. That said, there are quite a few exceptions, and even exceptions to the exceptions.
Another, somewhat reliable difference is their bodies; dragonflies tend to be larger, and have thicker, more burly bodies, while damselflies have thinner, more elegant looking bodies. This difference isn't just appearances; dragonflies are known to be much stronger, better fliers than damselflies.
One of the reasons for this is also the most reliable method for differentiating between them: the shape of their wings. Damselfly wings are all identically shaped and sized, whereas the hind-wings of dragonflies are larger than their forewings. This allows them to produce more lift and fly more efficiently than their counterparts. The wings of damselflies are also significantly thinner closer to their bodies, and thicken further out. Not only is this not as noticable with dragonflies, in fact, their hindwings are actually thicker towards their bodies, and thin as they go out.
I feel like citing sources again: A-Z Animals
Credits:
Created with an image by Said - "dragonfly close up with blurred out background"