Flesh Fly regurgitating its 'Cooling Bubble'

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dunksargent
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Flesh Fly regurgitating its 'Cooling Bubble'

Post by dunksargent »

Flesh-Fly-Inflating-its-Cooling-Bubble-PF.jpg
Flesh Fly observed November 6 2020 at Langdyke Countryside Trust's, 'Swaddywell Pit Nature Reserve' near Peterborough UK. The Flesh Fly was basking on a warm limestone cliff face in the heat of the afternoon Sun and continually 'regurgitating' and then 'reingesting', its 'cooling bubble' ... a regurgitated warm mix of digested liquid food. During such behaviour, as the 'bubble' evaporates, the 'evaporative cooling' process dissipates heat ... whence the cooled bubble is reingested ... to be warmed again by excess body heat ... and is then vomited into another 'evaporative cooling bubble'. Thus the fly's body temperature is regulated ... in a similar way to a domestic refrigerator cooling its contents.

Nikon 1 J5 / Nikon 1 70-300 / 4.5-5.6 VR / third party auto extension tubes / Zacuto 2.5x mag. optical finder. Small Gitzo aluminium tripod fitted with Novoflex fork mount; 300mm 1/200sec f11 ISO400 ... FF equiv. 810mm (1" sensor thus 2.7 crop factor)

A long lens, and thus long lens to subject distance, enables a high 'hit rate' for this type of photography.

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Last edited by dunksargent on Mon Nov 16, 2020 7:03 pm, edited 2 times in total.
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Lou Jost
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Re: Flesh Fly Inflating its Cooling Bubble

Post by Lou Jost »

Very interesting. I wonder why the fly doesn't just move to the shade though. That would be far more efficient than this laborious process.

dunksargent
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Re: Flesh Fly Inflating its Cooling Bubble

Post by dunksargent »

Lou Jost wrote:
Sat Nov 14, 2020 9:21 pm
Very interesting. I wonder why the fly doesn't just move to the shade though. That would be far more efficient than this laborious process.
Also part of its digestive process.

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Lou Jost
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Re: Flesh Fly Inflating its Cooling Bubble

Post by Lou Jost »

Yes, that makes more sense than the thermal explanation. It may be similar to what bees do with their gathered nectar to make honey. That gives it a reason to be in the sun. If so, it is not trying to cool, just the reverse.

dunksargent
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Re: Flesh Fly Inflating its Cooling Bubble

Post by dunksargent »

The whole 'evaporative cooling' process: https://www.nature.com/articles/s41598-018-23670-2

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Lou Jost
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Re: Flesh Fly Inflating its Cooling Bubble

Post by Lou Jost »

Thanks for the link. Very interesting. Almost all of the things they found could be just as well explained by the digestive hypothesis, but the fact that they do this bubbling behavior with higher frequency as soon as the lights go out does suggest that at least one of its functions is to cool the fly. It is too bad they didn't examine the relative cooling advantage (or disadvantage) of sitting in the sun and bubbling, versus sitting in the shade. Or maybe they would get too cold in the shade?

dunksargent
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Re: Flesh Fly Inflating its Cooling Bubble

Post by dunksargent »

Lou Jost wrote:
Sun Nov 15, 2020 8:31 am
Thanks for the link. Very interesting. Almost all of the things they found could be just as well explained by the digestive hypothesis, but the fact that they do this bubbling behavior with higher frequency as soon as the lights go out does suggest that at least one of its functions is to cool the fly. It is too bad they didn't examine the relative cooling advantage (or disadvantage) of sitting in the sun and bubbling, versus sitting in the shade. Or maybe they would get too cold in the shade?
From what I've read, different parts of an insect's anatomy are at different temperatures and it's advantageous for an insect's wing muscles to be warm ... Moths 'shiver' to keep their wing muscles warm ... hence some moth species are 'flight ready' on very cold nights. A fly 'in the shade' might not keep its wing muscles and wings as warm (and thus not optimally flight ready) as a fly basking in sunshine. Maintaining flight readiness assists a fly's ability to escape its predators. Some photomacrographers chill their specimens to prevent them escaping / flying.

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