I balk at the hyperbole of nature documentaries: “miracles of life” and “everything connected” and creatures “perfectly adapted” to their environments. But the transformation of a dragonfly from nymph to adult, no matter how many times I watch it, strikes me as utterly miraculous.
The metamorphosis is at once a fairy tale, a cheesy monster flick, and a Bildungsroman. I can’t help but frame the journey from aquatic monster to living fighter jet in these terms. The fragility of the newly-emerged teneral is striking compared to the toughness of both nymph and adult, and the lethal beauty of the adult opposes the ugliness of the (incongruously named) nymph.
I will try to tone down my rhetoric, though, and let the pictures speak instead.
Here is a nymph that’s crawled out of the water on one of my enclosures as it prepares to shed its skin. Notice the wing stubs on its thorax: they barely extend a third of the way down its abdomen. Speaking of which, its abdomen is fairly round and squat, whereas adult dragonflies are long and slim.
(Many of the photos I’m including are of the same individual, but because moulting can take several hours, I’ve also used pictures of other dragonflies that I found at an earlier or later step in the process. They also, I think, represent two different species, but I’ll have to get back to you with the IDs.)
The nymph’s exoskeleton splits along its back to allow the adult to crawl out. First come the head and thorax, followed by the legs, which at this point are too soft to hold onto anything. The dragonfly bends backwards as it pulls out of the old skin, while thin white threads hold it back.
The dragonfly’s wings are folded like origami and its legs are basically useless. It is hanging upside down over the water, and it will take an hour or more before it can do anything about this. Once a voracious predator underwater, it is now completely vulnerable. As soon as its legs are sturdy, it will do a fairly epic situp and crawl out of its old skin. (I managed to catch the latter step on video!)
Now the shapeshifting begins. The nymph had gills; the dragonfly is now breathing air for the first time and essentially inflating itself. (The air helps it force haemolymph, the insect equivalent of blood, into its folded tissues.)
The abdomen lengthens and narrows; the tightly folded wings bit by bit unfurl. The dragonfly’s colour changes from vivid green to darker green and brown, or, in other species, bright reds or blues. As the wings stretch out they become transparent. They are still very fragile, and wind or rain could damage them at this stage, potentially crippling the dragonfly.
Its wings are held together above its body, like a butterfly’s. Then suddenly they snap apart, fully extended. The powerful muscles in the dragonfly’s thorax begin to warm up. When it takes to the air, a dragonfly can reach 50 km/hr. This one is almost ready to go: