Crocothemis servilia servilia - Scarlet Skimmer
A few more scarlet skimmers. Not the bright red normally associated with the males of this species, but a male none the less. If you zoom in on the root of the abdomen, just behind the wing you can see the accessory genitalia. Dragonflies evolved a very unusual system for mating, were the male’s sperm is transferred to a false penis, a spigot just behind the thorax, in the underside of the second segment of the abdomen. Odonata are the only insects to use this method of sperm transfer.
I have been unable to find an explanation for this evolutionary development, but feel the need to offer my hypothesis.
Dragonflies have been around for approximately 400Ma and are one of the oldest bugs around. Flight was important for survival, but I will come back to that in the future, with more ideas.
Once long wings and a long thin body had started to evolve, it became advantageous to have longer wings which in turn meant that a longer body needed to evolve for balance. There became a limitation; the centre of gravity of the wings and abdomen meant that the dragon could not walk, all it could do was hook on. This meant that conventional abdomen tip mating was not possible. So the limiting factor for the length of the abdomen and consequently the length of the wings, was the CoG and the ability to walk and position for mating.
I can see a spigot at the base of the abdomen evolving, as it is a straight forward deformation. What I find amazing is that the dragon learned to use it, but he did, and it worked better than conventional, otherwise the faulty genes would not have spread.
Once the need to walk was no longer essential to life, the abdomen and wings could continue to develop. All this must have happened very early on, long before the split to damsels and long before the earliest fossils. I feel that this one evolutionary step is what enabled the odonata to develop beyond a crane fly geometry.
The above is not proven, accepted or scholarly fact, just my ideas on the subject.
The legs of the modern dragonfly are a series of hooks and levers, that push and pull on the perch to achieve stability, as seen above.
Location is Bandung, West Java, Indonesia. Alongside a stream and paddy fields.
The Scarlet Skimmer or Crimson Darter is a species of dragonfly of the family Libellulidae, native to east and southeast Asia and introduced to Florida and Hawaii.