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

Charles Krebs · Post by **Charles Krebs** » Fri Feb 09, 2007 9:33 am

Inspired by Ken's shots, I decided to rummage through some moss and look for some of those cute little springtails. Found a few right away! After taking an overall shot I moved in to take a closer look at the unusual eye, and then the feature for which it was named... the tail that allows it to "spring"... the furcula.

I believe the correct ID for this particular springtail is Dicyrtomina ornata.

rjlittlefield · Post by **rjlittlefield** » Fri Feb 09, 2007 9:45 am

WOW!

OK, Charlie, you've got me baffled again. These all look stacked. Pics 2 and 3, those I can understand, though I can only dream of ever producing this quality work. But pic 1, I can't figure out. These guys seldom hold still for long enough to get even a single good shot, let alone a stack. Is this another one of your CO2 jobs, or did you use some other trick to immobilize the beast, or am I just miscalibrated about what "stacked" looks like?

Many thanks for clearing up my poor confused head!

--Rik

PS. Nice touch on pic 1, positioning the beast so that just a bit of the furcula is visible underneath!

Charles Krebs · Post by **Charles Krebs** » Fri Feb 09, 2007 10:09 am

Rik... 1 and 2 are indeed anesthetized

... 3 is a different specimen, and...well.... not exactly anesthetized

The little bugger in 1 & 2 started doing its "springing" soon after these shots, so that was the end of that photo session. (Fortunately it stayed within the confines of the ping-pong ball dome... and was removed from the microscope stage!)

Stacks of 15, 13, and 67 respectively. (I'm not crazy about #3, wasn't adequately flat, required too many images... but it is an interesting feature, so I included it).

#1 was with 4X and 1.67X photo-eyepiece
# 2&3 were with 10X and 1.67X photo-eyepiece

beetleman · Post by **beetleman** » Fri Feb 09, 2007 10:34 am

A really strange looking creature Charles and a super set of photos also. I can see where it gets the name ornata

The eye is just fantastic...what a strange looking eye. Funny how the reflections make it look like eyeballs

Ken Ramos · Post by **Ken Ramos** » Fri Feb 09, 2007 11:24 am

Excellent images Charlie, especially those "eyes." A lot of argruments as to whether those are just ocelli or actually facets (ommatidia). I never found or ran across an agreement as to which.

rjlittlefield · Post by **rjlittlefield** » Fri Feb 09, 2007 12:19 pm

Once upon a time, I tracked down & posted quite a bit of information about the eyes of these beasts.

From http://www.photomacrography1.net/forum/ ... php?t=4417:

Ken,

You're not the only person to waffle about how to describe those eyes. At http://delta-intkey.com/britin/ord/www/collembo.htm, Watson and Dallwitz describe the Collembola as: "Compound eyes present and well developed (but composed of eight or fewer omitidia), or vestigial or absent. Ocelli 0–16 (the distinction between compound eyes and ocelli here being indistinct)."

http://www.cals.ncsu.edu/course/ent425/ ... ollem.html provides a similar description.

Other authors say that the collembola do not have compound eyes at all, e.g. http://entomology.unl.edu/lgh/insectid/ ... rygota.htm and http://www.cals.ncsu.edu/course/ent425/ ... photo.html. (The latter makes the additional refinement of calling the units "lateral ocelli = stemmata", and amusingly enough is inconsistent with the description at the closely related site linked in the previous paragraph.)

Obviously the beasts have what they have, and I doubt that the various authorities would disagree about the beasts themselves.

But in these on-the-edge cases, considerable confusion can arise in the descriptions, when one author for example decides to call the structure a collection of ocelli, and somebody else looking at the beast or a picture of one says "nope, can't be that -- this here is clearly a compound eye".

Ah, terminology, always a challenge -- can't live with it, can't live without it!

--Rik

Bruce Williams · Post by **Bruce Williams** » Fri Feb 09, 2007 2:49 pm

Amazing photos Charles - especially pic2. Now, are they reflections of your equipment in each eye component (whatever it is) or are we seeing some internal eye structure or surface colouring?

Bruce

rjlittlefield · Post by **rjlittlefield** » Fri Feb 09, 2007 4:41 pm

Bruce, let me go out on a limb here and speculate "some of each". The repeated white-eyeball-with-iris-and-pupil pattern looks ever so much like the inside of half a pingpong ball with the end of an objective sticking through it. But in each ommatidium, that pattern is overlaid or interrupted by some irregular brown markings. Everything I can see is consistent with reflection from a convex surface that's mostly shiny (where the eyeball pattern shows), with irregular patches of rougher stuff forming the markings. I doubt that we're seeing inside the eyes at all, but maybe it's possible to test that.

Charlie, do you happen to have any really high resolution shots of just the eyes? If the DOF in a single frame is significantly less than the depth of a single ommatidium, it would be interesting to know if there are any instances of seeing detail at the same position but two different depths, e.g. surface reflection & internal detail.

--Rik

Charles Krebs · Post by **Charles Krebs** » Fri Feb 09, 2007 7:51 pm

You are certainly seeing my ping-pong ball and the tip of the objective, but there may be something else there as well. Can't really say. Normally I would study these details as best I could, but this guy was slowly waking up, so I really only concentrated on quickly getting the images I needed. As Rik requested, here are a few images from a stack... greatly magnified (and I did not rotate them 180 degrees, as was done with #2). Sort of creepy looking actually... looks like he's been partying!

I'll probably look at this subject again, and I'll see if I can concentrate on this question.

MacroLuv · Post by **MacroLuv** » Fri Feb 09, 2007 8:01 pm

WOW! That is breathtaking!

I'm not surprised what his eyes looks like. You got him drunk Charles, remember?

Well, guys, if you proceed with this things you will force me to buy the microscope!

Charles Krebs · Post by **Charles Krebs** » Fri Feb 09, 2007 8:40 pm

OK... I know I'm over limit for today... but if you are going to try to analyze the reflections in the eyes this image is important. It's a top view of this critter, and it provides a perspective on the location of the eyes, and how they could be picking up reflections from the body, head, and antenna.

Charles Krebs · Post by **Charles Krebs** » Fri Feb 09, 2007 8:43 pm

Watch out Nikola... this can be an expensive place to visit if you get "hooked"!

rjlittlefield · Post by **rjlittlefield** » Fri Feb 09, 2007 10:56 pm

Charles Krebs wrote:OK... I know I'm over limit for today... but if you are going to try to analyze the reflections in the eyes this image is important. It's a top view of this critter, and it provides a perspective on the location of the eyes, and how they could be picking up reflections from the body, head, and antenna.

Um, yeah, you're way over limit for the day, but I guess as followup response to a question in the same topic we can cut you a little slack. Take a break tomorrow, OK? (Says Rik, the admin...)

Now, on the subject of what we're seeing, I'm still gonna go with the surface reflection theory. The newly revealed detail that's apparently below the surface of the eye facets looks exactly like the inside of a pingpong ball, with the slanted metal tip of the objective reflecting two hot-spots (I'm guessing you were illuminating from two sides, with the fiber tips pretty close to the ball), and a black hole in the middle where the objective's lens would be. And being "below the surface of the eye facets" is exactly what we'd expect for the reflection from a convex mirror. I guess if we knew the surface curvature we could compute where the reflection should appear to be, but that's a bit beyond me at the moment.

It's hard to tease out this kind of information. I guess one way might be to vary the lighting and see what stays the same. Dunno, have to think about this for a while.

--Rik

Bruce Williams · Post by **Bruce Williams** » Sat Feb 10, 2007 4:24 am

Very convincing follow up photos and arguement - thanks guys.

So, he or she was checking out your equipment then Charles (hmmm - wording rather open to misinterpretation

). Yes you can clearly see that it is multiple reflections of the ball and objective lens (comprehendable yet still amazing when you consider just how small those "eyes" actually are!).

That last photo's a real cutie - I hope he's safely back home with his mother after his big adventure - he is isn't he Charles?

Bruce

Ken Ramos · Post by **Ken Ramos** » Sat Feb 10, 2007 6:22 am

You know the more that I look at these, for the lack of a better term "eyes," they seem to be or to me anyway, vestigial tissues of what would have been compound eyes, had mother nature not changed her mind. Much like the "webs" between our fingers or our toes! Was it once intended that man would or should have had webbed appendages, enabling him to move about in an aquatic environment much more effeciently than what he does now or attempts to do now and that preconcieved idea/notion aborted, for what would be now obvious, reasons?

So maybe the Springtails were once intended to have compound eyes but considering their environment they were really not really necessary, seeing as how they are detritivours and not an agile hunter species of insect. So the formation of compound eyes was aborted.