Wednesday, March 31, 2010

Birth of a dragonfly

The cobbled, narrow streets of the ancient Guatemalan city of Antigua. As our crew rolled into town in our magic birding bus, I noticed Wandering Gliders, Pantala flavescens, patrolling these lanes, darting through traffic. Wandering Gliders are one of the world's most widely distributed dragonflies, so it wasn't that surprising to see them here.

The lovely grounds of Los Andes, a very eco-friendly finca that we spent time at. The following drama all took place in that little hemispherical-shaped pool, just to the left of those blue chairs.

The shed exuvia of a Wandering Glider, with a one Quetzal coin for a size comparison (about the size of an American nickel). One evening, Chuck and Barbara Vellios and myself took a nocturnal prowl around the grounds of Los Andes, and spotted this very nymph climbing from the water. Once high and dry, it locked itself to the wall and we were witness to one of the most spectacular transformations in the insect world.

After a short while, we could see the top surface of the nymph begin to rupture, as the dragonfly contained within struggled to escape. Dragonflies live most of their lives in the larval stage - nymph - and are competely aquatic during this phase. Wandering Gliders are certainly among the quickest to go from egg to adult - they can do so in five weeks or so. Some large dragonfly species might live several years under the water as a nymph.

It didn't take long for the fledgling dragonfly to burst out of its shell - termed an exuvia by this point - and reach the position pictured above. Note the tiny whitish wing buds, barely projecting. The whitish threadlike filaments are termed tracheal tubes, and transport oxygen to the young dragonfly.

Not long after I took the previous photo, the dragonfly began energetically flexing and stretching its legs. Then, it snapped around like an acrobat, flipping over in less than a second and reversing its position. This movement freed its abdomen from the cramped confines of the exuvia, and allowed it a far superior position to commence full expansion.

About 15 minutes later. Note the dramatic expansion of the wings. At this point hemolymph - the dragonfly version of blood - is being energetically pumped throughout the insect, causing body parts to expand and harden.

Less than an hour after emerging, the young glider had reached this point. The very broad wings, characteristic of this highly migratory species, are already evident.

A scant ten or fifteen minutes later, and the wings have nearly expanded completely, the network of veins conducting fluid throughout their length and breadth. At this point the animal is defenseless and very vulnerable to predation; this is why dragonfly nymphs typically emerge from the water and transform at night, when fewer potential predators are about.

Not much longer than an hour after emerging from the exuvia, the glider looked like this. Wings are nearly fully expanded, but not yet snapped to the horizontally extended position of a mature adult. The eyes are gaining much of their color, as is the tissue of the thorax and abdomen.

In th blink of an eye, the wings suddenly folded to the horizontal position.

In about an hour and a half, the Wandering Glider looked like this. At this fragile stage, it is termed a teneral, not yet fully hardened nor capable of swift and agile flight. Probably 24 hours later, this glider was on the wing and far away, or at least I hope so.

Dragonflies, especially this species, are not rare so the transformational event that we just saw isn't rare either. Nonetheless, it was amazing to watch and I feel fortunate to have had the opportunity.

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6 comments:

Janet Creamer said...

Very cool, Jim!

Tom said...

Yes, very cool. Although I know that the wandering glider has a worldwide distribution, seeing your photos from Guatemala of the same species that I see cruising over the parking lot at Fountain Square is pretty cool.

On another note, somebody found one outside the office a few years ago- they thought it was dead, but I think it was really just cold. After a few minutes in the office warmth, we had a glider wandering the cubicles of building F.

Tom

Ian Adams said...

Jim:

Excellent photos of the "birth of a dragonfly". I imagine that our warm early spring days will herald the arrival of a few odonates in the Buckeye State over the next couple of weeks.

Enjoy...

Ian Adams

Lisa at Greenbow said...

I am so glad you showed this. I have never seen such a metamorphosis.

Dave Lewis said...

That was the best post on a blog I have seen!
Thanks Jim!

OpposableChums said...

Just amazing that that transformation could happen so dramatically and so quickly.

Excellent post. Much thanks.