Who's on Top?
Since the previous post several people have asked me to explain the unusual mating position of dragonflies and damselflies. Look closely at this mating pair of Orange Bluet damselflies. Can you figure out what is going on?
Something of a puzzle isn't it? These beautiful creatures are in a "copulating wheel" -- supple acrobats performing a most unusual method of sexual reproduction. Both partners have long thin abdomens which appear firm and straight when we see them in flight or at rest. But when it comes to sex, flexibility is the key. Examine the damselfly on the bottom: it seems quite remarkable that what usually appears to be a straight, rigid abdomen is in an extreme bend upward with the tip positioned flat against the first segments of the top damselfly's abdomen.
What a peculiar mating position. Most of us assume male and female animals, including insects, have their reproductive organs on the end of their abdomens and that the two ends must join together for sexual reproduction to occur. Then why this odd anatomical arrangement for damselfly and dragonfly species?
Here are two dragonflies in the mating wheel. Who is on top? Is the female on top receiving sperm from the male on the bottom? Or is it the other way around?
To know the answer you have to understand the sexual anatomy of male odonates. Picture this: the penis of male dragon and damselflies is not even connected to the part of the body that makes the sperm! Male odonates have sex organs located in two separate places on the abdomen. In order to mate, the male must physically transfer sperm from his gonopore, (located on his ninth abdominal segment near the end of his abdomen) to his secondary genitalia, a sperm reservoir and penis, located under his second and third abdominal segments (the part of his abdomen closest to the thorax).
A few years ago on one summer day while walking along the edge of a pond, I found myself very fortunate to witness this exchange. I watched a male Variable Dancer damselfly, perched on a reed, repeatedly curl his lower abdomen forward to transfer sperm from his gonopore onto his genitalia located further up. Curling and tapping, curling and tapping -- he went through this motion a number of times. When he was through, he sat and watched in search of a mate. Then suddenly he took off. Here he is with his abdomen in mid-curl:
To capture his mate, he would grasp her behind her neck with the pair of cerci located at the tip of his abdomen. The female would hold on curling the end of her body upward touching his penis with the tip of her abdomen to receive his sperm. Thus their mating wheel would be formed.
Here is one more photograph: it's a pair of mating Meadow Hawk dragonflies. And with the above information and the description of male odonate anatomy in particular, you now know who is on top!
Linda, these are gorgeous photographs, and it's wonderful that you can explain to the rest of us what the insects are doing. And how you can find these creatures in the act of mating is amazing. Thank you for sharing it all!
By Jove I get it… But it took 3 readings!
Linda, you must have been going in circles making sure your explanation was clear enough for your readers to understand what was going on! What patience to get all these photos at the right moment.
Amazing information and equally amazing photographs! Bravo!
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