Springtail tales... and tail (Great update 2/13)

[Charles Krebs]

Well Bruce... he made it off the microscope OK, but became airborne before I got him back outside! So last I know it was hopping around my kitchen.

When you look at the first and last images, it is interesting to me how the configuration of the eyes, and the head shape would seem to block all "sensing" of anything below. Must be an optimistic creature since everything is "looking up".

[rjlittlefield]

Must be an optimistic creature since everything is "looking up".

Or maybe all the threats come from above...

--Rik

[Charles Krebs]

When I originally posted this I tried to ID the species, but there were a few that were very close in appearance (at least to me!). I sent an email to Frans Janssens, Department of Biology, University of Antwerp, Antwerp, Belgium from the link on the excellent site http://www.collembola.org/ . He was gracious enough to help with an ID, and as a bonus was extremely informative about the eyes. So here is the info from his response:

Your determination is close. Quite close. IMHO, this specimen is Dicyrtomina cf. saundersi. Which is a very very close relative of
D. ornata. The difference bewteen the 2 species is easiest to spot if you look at the black pigment patch at its butt. If this patch
is roughly shaped as a rectangle , it is ornata. If the patch is shaped as a Maltheser cross, it is saundersi. In your pictures this
patch is not well pigmented, so hard to recognise, but it seems there are some transversal stripes (= part of the Maltheser cross).
A second character to distinguish the two species = the colour pattern of the 2nd antennal segment. If the colour is uniform or
gradually changing from light to darker, it is ornata. If the 2nd antennal segment is apically and basally lighter in colour (and in
the middle darker), it is saundersi. This can be observed clearly in the last picture of your series of photographs.
I use the clause 'cf.' in the name to indicate that this name is not (yet) used in the USA. Currently, US taxonomists use the name
D. minuta. But this name is used in Europe for a different species... In summary: while in Europe 3 different species names are used
for 3 different but related colour forms of Dicyrtomina, in the US these 3 related species are lumped together under 1 species
name... As long as this taxonomic mess is not resolved I prefer to use the cf. clause to name the US specimens with the associated
European names.

I was not able to post a reply to the forum. There is no guest account...
With respect to the discussion about the terminology of the eyes, I would like to add that the eyes of Collembola are not 'compound'
eyes but 'composed' eyes. In the literature on Collembola, the single eyes of such composed eye are often called ocelli for
convenience. But they are in fact a kind of ommatidium. But be aware that the ommatidia of insects are quite different by internal
structure from the ommatidia of Collembola. E.g. ommatidia of insecta have a cuticular lens, while ommatidia of Collembola lack such
a cuticular lens. Ommatidia of insects have a crystaline cone that serves as an optical guiding device to deliver the by the
cuticular lens focussed light beam at the optical sensitive nerve cells. Ommatidia of Collembola have a spherical crystal to focus
the light beam at the optical sensitive nerve cells. The crystaline device of insects is an intracellular product, while that of
Collembola is extracellular. The ommatidia of insects are 'touching eachother' forming as such all together the compound eye.
Ommatidia of Collembola never touch eachother. That is why this kind of eye is called 'composed' and not 'compound'.
Could you post this to the forum, pls.


Kind regards,

Frans

My appreciation to Frans for his detailed, informative reply.

[rjlittlefield]

My appreciation to Frans for his detailed, informative reply.

I'll second that!

I especially appreciate the info about eye structure. It is much more detailed and helpful than anything I found before.

Frans, I assume you're watching even though you can't post. The reason that we don't have a guest account is to prevent spamming. We can barely keep away the porn- and drug-peddlers even using administrator-approved registrations.

Again, many thanks!

--Rik (site admin)

[Harold Gough]

Rik 1 and 2 are indeed anesthetized

Using CO2?

Harold

[Charles Krebs]

Harold,

Clove oil. The slide with subject was placed in a small container with a piece of paper towel soaked in the oil. I suppose it's the eugenol in the clove oil. It was removed from the container while very "groggy" (too long would likely kill it.)

[Harold Gough]

A devilish ruse!

Thanks for that , Charles.

Harold