What is this I wonder...

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D0c
Posts: 267
Joined: Mon Nov 30, 2020 9:13 pm
Location: England

What is this I wonder...

#1 Post by D0c » Thu Feb 11, 2021 7:01 pm

What is this I wonder.

Have spent quite a few hours now looking through all my online PDF books and I cannot find a name for this little critter.

It moves damn quick and is very hard to image.

EDIT: It might be is a Metopus but it's not like the normal shaped ones I see, but then it does twist while it swims.

https://www.flickr.com/photos/154534235 ... datetaken/
https://www.flickr.com/photos/154534235 ... datetaken/
Leitz SM-Lux

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: What is this I wonder...

#2 Post by Bruce Taylor » Thu Feb 11, 2021 7:15 pm

Caenomorpha. You must have some low-oxygen water, there. :)

D0c
Posts: 267
Joined: Mon Nov 30, 2020 9:13 pm
Location: England

Re: What is this I wonder...

#3 Post by D0c » Thu Feb 11, 2021 7:34 pm

Is it the same as this one as I've identified this i think to Caenomorpha medusula because of the posterior spine

https://www.flickr.com/photos/154534235 ... datetaken/

As far as the low oxygen water, these are from a 2 litre jar that I keep all my samples in, I do supply it with oxygen a few times a week via an air stone pump.
Leitz SM-Lux

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: What is this I wonder...

#4 Post by Bruce Taylor » Thu Feb 11, 2021 8:33 pm

To my mind, it looks different. The one you're calling C. medusula has a very long posterior spine under a bell-like hood, giving the whole thing a Medusa-like appearance. The other one has a more screw-like body, perhaps suggesting C. sapropelica. However, I wouldn't settle on a species until I'd reviewed all the literature (which I haven't done).

Caenomorpha is an anaerobe, so I guess there some pockets of low-oxygen water in your jar. :)

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