Diptera.info :: Identification queries :: Other insects, spiders, etc.
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 Freshwater Cladocera
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| blowave |
Posted on 06-01-2012 20:36
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 Member Location: LINCOLN, UK Posts: 3151 Joined: 27.06.07 |
Hello, I have searched high and low and cannot find anything which looks like this. They were floating near the suface in shallow water in my pond on a warm day on 15th October, near Lincoln UK. Size no more than 2mm, one photo shows a Chaoborus larva amongst them. Janet blowave attached the following image:  [140.34Kb] http://cubits.org... |
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| blowave |
Posted on 06-01-2012 20:36
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Member Location: LINCOLN, UK Posts: 3151 Joined: 27.06.07 |
....
blowave attached the following image:  [140.81Kb] http://cubits.org... |
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| blowave |
Posted on 06-01-2012 20:37
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Member Location: LINCOLN, UK Posts: 3151 Joined: 27.06.07 |
cropped from the above shot..
blowave attached the following image:  [133.07Kb] http://cubits.org... |
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| blowave |
Posted on 06-01-2012 20:38
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Member Location: LINCOLN, UK Posts: 3151 Joined: 27.06.07 |
I'm not sure if this is the same..
blowave attached the following image:  [92.84Kb] http://cubits.org... |
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| Moo |
Posted on 07-01-2012 08:52
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Member Location: Posts: 21 Joined: 31.07.08 |
My guess is that the last image is a basically dorsal view, and the previous is a lateral view. An unusual subject for diptera.info! I had a search and couldn't find anything that looked right either. |
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| atylotus |
Posted on 07-01-2012 11:02
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 Member Location: Amsterdam, NL Posts: 1126 Joined: 29.05.09 |
You already guessed that it was a Cladoceran for it has a single median dorsal eye, two "valves" on either side of the body and two "legs" which are in fact the antenna. All crustaceans, inclucing Cladocerans, have 2 pairs of antenne. There is also a single true leg, but this is placed at the ventral side of the body, moving between the valves. However, I think I see a large ventral spine (a pointed extension of these valves), so the genus Daphnia seems the most likely candidate. And 2 mm is quit large for a Cladoceran, and to my knowlegde Daphnia reaches this length. |
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| blowave |
Posted on 08-01-2012 17:10
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Member Location: LINCOLN, UK Posts: 3151 Joined: 27.06.07 |
You could be right about the dorsal view Moo, but I wasn't sure as the big antenna at the top didn't seem to correspond with one on the opposite side in the first photo. All those in the photo with the Chaobrus larva looked to be swimming with a big antenna at the top, apparently lacking one at the bottom but having some sort of a leg at the bottom or ventral side. The last photo shows two antennae, equally on either side. atylotus, I had a lot of what looked like Daphnia within a very short time of building and filling the pond in 2009, since then I have had ducks which visit from late February for a few months then they disappear but they must feed on these. There's also a lot more foliage cover so I can't see as much as I did in the first few months! The Daphnia I have seen all look to have an eye and antennae near the 'head' end, this has both further back much more like a Cyclops but it doesn't seem to fit any of thos I can find either. I have found several keys but can't fit this anywhere. There is a picture based key albeit in the USA but Ihaven't found anything close there either.. http://cfb.unh.ed...index.html There might be something in this pdf but I haven't been able to pick anything out, there's 75 Cladocera of which 73 are present in the UK. http://www.boxval...osters.pdf The pdf is from Norway, I couldn't get the site link last night but it's now coming up.. http://www.nina.n...ceans.aspx Links from the Cladocera Interest Group UK, I may be able to find more out there but thought someone here might recognise it. http://www.boxval...ads.asp#SP I have photos from September 2009 of a few different Cladocera, there was a lot of very small ones similar to this, the one with the egg shell nearby gives an idea of the size. The egg case was ~1mm or very slightly more in length. blowave attached the following image:  [149.09Kb] http://cubits.org... |
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| blowave |
Posted on 08-01-2012 17:12
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Member Location: LINCOLN, UK Posts: 3151 Joined: 27.06.07 |
Close up of the very small ones, they look to belong to the same group.
blowave attached the following image:  [189.95Kb] http://cubits.org... |
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| Tony Irwin |
Posted on 09-01-2012 20:52
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 Member Location: Norwich, England Posts: 7226 Joined: 19.11.04 |
I contacted Adrian Chalkey about this. Adrian runs the Cladocera Interest Group ( http://www.boxval...cindex.asp ). He only looked at photo 3 which I sent to him while the site was down. He said "I've been looking at the photo - or squinting at it I should say, rather blurred so it helps a bit. The swimming antennae seem to have two similar length, long branches - and though you cant clearly see how many segments they have it just seems to me to have the jizz of Daphniidae. That said the head looks small compared to the body shells. What threw me at first was the long oval shape of the body, then I realised the photo is taken, not from side on, but mostly from above and only slightly from one side, you can just see the two halves of the shell separating below the head. So the angle of the photo distorts the height of the waterflea, compressing it, though the width is correct. Allowing for that, with the small head and relatively large radius of the shell below the head I'd say it is probably a Simocephalus species. Obviously I can't say if it is S. vetulus, S. exspinosus or S. serrulatus, the three species we have in Britain. Interesting photo, I'm far too used to seeing Cladocera under a microscope at 90 degrees or whilst alive and moving so it's good to try to work out a still image taken whilst swimming. I don't get sent many casual snaps of waterfleas!" Tony ---------- Tony Irwin |
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