After getting up this morning, I went out to check my tanks to see if anything had happened during the night or might happen. I was greeted by one of the Large Red Damselfly nymphs just sitting below the surface and in the other tank, a Hairy Dragonfly nymph doing the same. There are a few reasons why during the winter months for the past couple of years I have decided to rear a few species through to dragonflies and damselflies. One is to be able to photograph the emergence of the species which I may not be able to see otherwise and more importantly I suppose, to be able to study the nymphs in the tank under the water as they go about their business and try to learn something new about their lives or identification features. Today, I may have just done that..... or maybe not! Whilst watching the Hairy Dragonfly nymph which was sitting on the top of some weed, I could clearly see that the back of its head was slightly clear of the water and I was drawn to two white specks on the back of the head. The more I looked at these, they looked like gills or openings but as far as I knew or thought I knew, I assumed they raised their heads out of the water to start to breathe air as we do through the mouth. I went and got the camera and took a few photos which clearly show this opening.
Hairy Dragonfly Nymph
Maybe I am completely wrong and this opening is not that and just aids the head to turn but maybe I have found something that I never knew. Feeling a bit confused I then looked in the other tank at the Large Red Damselfly nymph and could see the same feature on this species. Wanting some answers, I then looked through some books I have and then looked on the internet but both failed to deliver any information. I hope that someone reading this or looking at the photos will be able to reach a conclusion and let me know but either way, its another fascinating aspect to what can be learnt if you put in the time and study these superb insects.
Hairy Dragonfly Nymph
A truly excellent excersise of the observation/study/and illustration of these creatures Marc, you must be up with the leaders in this field in my view....Brilliant.
ReplyDeleteMany thanks for your kind words Pete, much appreciated. Always looking to learn.
DeleteHey, I found this text from Wikipedia: Larvae breathe gills: delicate dragonflies have external gills at the tip of the rear of the body, (Anisoptera) gills are inside the rectum.
ReplyDeleteMany thanks Anne for this. I was aware that the hawkers breathe through their rectum but wasn't sure about the process of changing from water to air. All interesting stuff to know abd learn.
DeleteVery interesting facts Marc,amazing captures.
ReplyDeleteJohn.
Many thanks John. I still have no answer yet though.
DeleteFantastic images Marc, you get better each time.
ReplyDeleteThanks Bob, appreciated.
DeleteWonderful observation and images, Marc! Perhaps you have discovered something new to science? It's certainly another feather in your cap, anyway!
ReplyDeleteBest wishes - - - - Richard
Many thanks Richard. Its certainly a feature that I was not aware of before. Hopefully it will be solved soon.
DeleteInteresting stuff
ReplyDeleteI suspect its nothing to do with breathing. The following comes with the disclaimer that this is from memory and my understanding of others work! Dragonfly nymphs are secondarily aquatic, ie.e they evolved from terrestrial insects, and they have internal gills that effectively allow them to breathe air underwater in a way. The oxygen diffuses from water into air in their tracheae, a network of tubes that carry air/oxygen around the body. When a dragonfly nymph moults into an adult you can see white tubes linking the gills to the spiracles on the abdomen allowing it to breathe just before and during the moult, which drop off once they fully emerge and the adults breathe through the spiracles. I have even seen soon to emerge hawker nymphs sticking their rectum above the water to breathe. One individual turned upside down and went inactive when I put it a deeper pot thinking the water was too shallow, but revered when put back in shallow water.
Interesting the bit protruding from the water appears to be the area the nymph skin/exoskeleton splits. Perhaps this is not a coincidence and it is checking the condition above the surface to see if they are suitable for emergence - temperature, moisture, wind speed etc. ? Just guess tbh
Thanks Neil. An interesting read. All good stuff to learn and understand. I will continue to monitor but its certainly a good learning curve. Still interested why just this area sticking out of water though. Your theories may well be correct.
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