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Posts Tagged ‘exuvia’

Whenever I walk along the edge of a pond, I always like to look for damselflies, which love to perch on the vegetation growing out of the water. Footing can be a bit problematic and more than once I have slid down a slippery bank into the water. Normally, though, I just lean out as far as I dare to get some shots.

Last weekend as I was exploring Jackson Miles Abbott Wetland Refuge, I spotted this beautiful little damselfly that was looking in my direction. I knew that depth of field would be a problem from that position, but did my best to focus on the damselfly’s beautiful eyes. When I returned home and began to review my shots, I was a little shocked to see what looked to be the discarded exoskeleton (exuvia) of another damselfly (or possibly a dragonfly) on the underside of the leaf on which “my” damselfly had perched. How did I not notice that when I was shooting?

I really like the way that the head of the exoskeleton is facing that of the damselfly and the shadow in between the two of them. Is it the shadow of the one looking down or the one looking up? Common sense says that it is the former, but the slight degree of ambiguity adds interest to the photo for me.


damselfly

© Michael Q. Powell. All rights reserved.

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When I noted in a recent posting called Transformation, that I had not yet witnessed the remarkable metamorphosis of a dragonfly, I never suspected that only a few day later I would somehow manage to observe such a transformation of a Common Sanddragon dragonfly (Progomphus obscurus) from start to finish at relatively close range.

Nymphs of this species of dragonfly crawl out of the water onto a sandy beach to begin the process and I knew of the bank of a stream where this had been taking place over the past week or so, having observed there newly emerged teneral dragonflies and the discarded exoskeletons known as exuviae. However, what were the chances that I would be able to be at the right location at precisely the right time? I figured the odds were about the same as winning the lottery.

Last Friday around noon I spotted several exuviae in the sand as I was walking along that section of the stream. I bent down, picked them up, and placed them in the palm of my hand in order to get a good look at them. Having spotted Unicorn Clubtails in this location along with Common Sanddragons, I wondered if these was a way to tell which species of dragonfly had emerged from a given exuvia. As I continued to walk, I suddenly became aware that something was crawling around in my hand—one of my presumed exuviae was in fact a live nymph.

I experienced an initial moment of shock, but realized pretty quickly that I needed to get the nymph back onto the sand. If I had been thinking a little more clearly, I might have chosen a spot that optimized my chances for capturing good images, but instead I selected a location where I could see another exuvia and gently placed the nymph there.

I placed my eye to the viewfinder of my camera and began to wait and to watch. Within a very short period of time I began to see signs of movement in the thorax area of the nymph, just behind the eyes, and before long the head of the dragonfly appeared as it began to pull its body out of the soon-to-be-discarded shell. It took about eight minutes for the body to be entirely free of the exoskeleton.

The dragonfly changed positions so that it could extend its abdomen and begin the process of extending its wings, which at this stage were merely nubs. Over the next twenty minutes or so, the wings and the abdomen grew larger and larger. My original shooting position was no longer optimal, so I ended up standing in the stream to get a view of what was happening. The water was about six to eight inches deep (15 to 20 cm) and my non-waterproof boots were quickly soaked. As I crouched to get as close as I could to the eye level of the dragonfly, I suddenly realized that the seat of my pants was getting wetter.

Twenty seven minutes after the process had started, the wings of the newly emerged dragonfly snapped open to the familiar position of dragonfly wings. At this moment they were very clear and obviously very fragile and I experienced a moment of concern for the vulnerable dragonfly when a slight wind kicked up. Fortunately, though, I had chosen a somewhat sheltered position and the dragonfly was safe. The wings continued to harden and six minutes later the dragonfly flew off to some nearby vegetation to begin its new life.

I took a lot of photos of the process of metamorphosis and it was hard to choose which ones to post. In the caption area of each of them,I have indicated the time at which the photo was taken. The transformation began at 12:19 and the dragonfly flew away at 12:52.

Fellow dragonfly enthusiast and photographer Walter Sanford witnessed the emergence of a Common Sanddragon at a nearby, but different location on 1 June and did a blog posting on it today. Be sure to check out his posting for some great photos and a detailed explanation of what is happening within the dragonfly’s body as it undergoes this dramatic metamorphosis.

Common Sanddragon

12:19 indications of first movement

Common Sanddragon

12:21 head starts to become visible

 

Common Sanddragon

12:22 dragonfly starts to pull out of shell

Common Sanddragon

12:22 body of dragonfly starts to be visible

Common Sanddragon

12:23 body significantly out of shell

Common Sanddragon

12:24 side view of dragonfly pulling body out of shell

Common Sanddragon

12:25 struggling to get abdomen out of shell

Common Sanddragon

12:27 body completely freed

Common Sanddragon

12:27 straightening the abdomen

Common Sanddragon

12:28 starting to extend wings

Common Sanddragon

12:29 continuing to extend wings

Common Sanddragon

12:31 wings extended

Common Sanddragon

12:40 wings reach final length

Common Sanddragon

12:48 wings fully opened

Common Sanddragon

12:52 close-up of newly emerged dragonfly

© Michael Q. Powell. All rights reserved.

 

 

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Dragonflies spend most of their lives as nymphs in the water.  When the time is right, they crawl out of the water, break out of their exoskeletons, and turn into the colorful aerial acrobats that I love to watch and to photograph.

Although I have seen photos and videos of this amazing transformation, I have not yet witnessed the entire process in person. However, this past weekend I did spot some newly emerged Common Sanddragon dragonflies (Progomphus obscurus) at Huntley Meadows Park. Nymphs of many dragonfly species attach themselves to vegetation as they undergo their metamorphosis, but Common Sanddragon nymphs merely crawl out of the water onto a sandy area at the edge of a stream.

After I had spotted the dragonflies, I scoured the sandy stream bank and managed to find some cast-off skins (exuviae). Looking at the exuvia in the photo, you can see how the nymph has broken through the shell just behind the eyes and crawled out. The stringy white things on the top of the exuvia are breathing tubes used by the nymphs.

My last image is a visual reminder of how complicated and delicate this transformation can be be. The dragonfly obviously had some kind of a problem in expanding its wings and it is doubtful that it was able to survive for very long.

Common Sanddragon

Common Sanddragon

Common Sanddragon

Common Sanddragon exuvia

Common Sanddragon

© Michael Q. Powell. All rights reserved.

 

 

 

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