Dragonflies

Originally published July 21, 2010 (The Manitoban, Vol. 98, No. 2)

Do you remember how much you loved Filmon Fridays when you were a kid? A whole day off school?! Man, it was incredible. What have we got that can compare these days? Lackluster dreams of bringing back the Winnipeg Jets? Perfectly good streets quietly and without fanfare being renamed after football players? Come on, Katz-- I want action. I want novelty. I want good ideas. I want a political platform that includes the introduction of a 'Dragonfly Appreciation Week'.

You might think this a departure from the vision of Zoological Investigations, to write about a common and typically well known animal such as the dragonfly, but there are many wonderful facts about dragonflies that I am willing to bet whole packages of Popeye cigarettes the average person on the street just simply doesn't know. 

For starters, dragonflies have been gracing this lovely old rock with their presence for the last 300 million years! They are thought to be one of the first insects that evolved wings (which are derived from the integument or skin, not the limbs) and the ability to fly. The ancestors of today's dragonfly species had wingspans of 20 to 50 centimetres! Just think about that for a second, will you? Popular belief tells us they were able to grow so freakishly huge because the atmosphere during that period (the Carboniferous) contained way more oxygen than it does today, enabling dragonflies to ventilate such a massive body (no lungs for insects, only spiracles and a tracheal system, thank you). Today there are about 5 000 described species of dragonflies and their close relatives the damselflies. 

 

Next up on the list of Odonatous wonders: those four lovely wings. They can beat them synchronously or individually, allowing such elegant flight maneuvers as hovering, taking off backwards, unbanked turns, rapid acceleration (up to nearly 40km/hr) and basically as far as flight goes, they just own the sky. They can fly in tandem while mating, kind of like those crappy love scenes in the old Superman movies. Dragonflies have compound eyes made up of repeating units of a simplified visual receptor called an ommatidium. They have up to 30 000 ommatidia per eye that receive light from whichever direction they are pointing in, giving them an almost 360 degree viewing field. Their vision is binocular, allowing them to judge distances accurately and they see in colour (except red), UV, and detect polarized light. The eyes are also highly sensitive to motion and can detect movements separated by up to 1/300^th of a second, which would make watching a movie look like a series of still photos. The main downside to this masterpiece of an idea is that because the focus cannot be changed near images appear blurred but with all those other great features, who cares? Most things tend to look worse up close anyhow, except perhaps lady dragonflies. 

 

As most of us know, dragonflies are voracious predators of other insects in the adult stage, but they are also magnificent killers during their juvenile, or nymph phase of life, which can last anywhere from months to several years in different species. Dragonfly nymphs hang out in the water, eating most anything they can catch with their big, nasty extensible jaws (think Alien). They've even been known to bite humans. They breathe through gills in their rectum, which makes me giggle but don't get me wrong, I respect the hell out of dragonflies. On the subject of rectum, the nymphs can propel themselves suddenly by rapidly ejecting water out of their anus, like some kind of super-fart sneak attack.

Is this sampling not enough to convince you of the merit Dragonfly Appreciation Week holds? Well, dragonflies are all over the place in folklore because they are historically known for being super badass and way cool. In Romania, dragonflies were said to be horses possessed by a devil and in Sweden, folklore states that the devil uses the dragonfly to weigh people's souls. With the number flying around in my backyard these days I can't tell if it's a good or a bad sign, but I am a bit nervous after hearing that one.

Dragonfly larvae are aquatic

Adult dragonflies are not.