# The "Pearl Crack" Experiment



## cloud jaguar (Jan 7, 2009)

What follows is the Pearl Crack Experiment. Ok so my wife and i are not geneticists, or biologists, or any other type of ists. Our brand of science is that peculiar to disciples of the liberal arts who merely dabble in keeping mantids. That said, this is what we did:

METHODOLOGY:

Purchase 1 packet of "Pearl Crack." In case you are wondering, this is crackle texture origami paper made in japan. Pearl crack gets its name because it is textured with all of these cracks and ridges, not just in color but in actual shape. Also it is irridescent / opalescent. www.sasugabooks.com/product_info.php?products_id=43448 or www.kidstoyo.co.jp

Some on this forum strongly believe that texture vs color enhance polymorph color in test subjects S. Limbata, that is why we used the crack textured paper, to cover both bases, so i guess we will never resolve this mystery. We taped the pearl crack outside their enclosures thusly:

4 covered 1/2 of surface area with neon pink,

4 electric blue, and

4 golden yellow.

TEST SUBJECTS:

Test subjects are 12x L3 S. Limbatas that all were born green phase.

CONTROL:

4 L3 s. limbatas green phase. 20 s. limbatas L1 mixed phase mostly mottled brown.

Ok so we put them in yesterday and will now wait for the multi colors to occur with crossed fingers - won't hold our breath for too long though!

~Arkanis


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## Rick (Jan 7, 2009)

Interesting but I don't think it's gonna happen. Keep us updated.


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## Peter Clausen (Jan 7, 2009)

So, you're testing for color then? (all surfaces are equally textured?) So, this wouldn't be a color vs. texture experiment. It's a color experiment. A flat piece of paper has a texture value (equals nearly zero).

I am very interested in the results, but my expectations are in line with Rick's. I've placed different colors near mantises in the past and observed no changes in mantis color. But, maybe I didn't have enough color AND texture!

Your sample sizes are too small to really draw safe conclusions from. However, just because you get a result, doesn't mean it would _not_ fall precisely in line with the true nature of things.


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## chun (Jan 7, 2009)

it's a good idea to control for genetics (i.e. by using the nymphs from the same ootheca) and environmental conditions (temperature, humidity and photoperiod) so that any subsequent polymorphism occuring are results of the variables you are testing (colour and texture) rather than the uncontrolled variables (genetic, environmental conditions etc). As Peter mentioned, the sample size is too small, the absolute minimum sample size for each variable should be 5 for (albeit, very weak) statistical analysis. Otherwise, the conclusions drawn from this investigation would be very weak and inconclusive.

out of interest, why are you only covering 1/2 of the surface area with pink neon? Also, what are you actually controlling for in the 'controlled' variable?

Hope this helps with your experimental design.


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## Orin (Jan 7, 2009)

Texture color changes noted in insects (green versus brown) have to do with the 'perch' texture such as a smooth wire versus a rough coated wire or coated plastic screen versus metal screen.


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## kamakiri (Jan 7, 2009)

Hey Arkanis,

Good to hear you're taking more formal action on this than I am. I'm just using a few colored post-it notes outside some of the deli tubs, and will transfer some later to colored top critter keepers.

Also got two colored aquatic plants (got ones with suction-cup bases):







Probably going to also get some red and pink silk flowers.

G-


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## PhilinYuma (Jan 7, 2009)

How cool is that, Arkanis!

I'm not sure that the experiment is very rigorous scientifically, but it certainly reflects your and your wife's liberal arts background.

This sounds a lot like the experiment conducted by the Syracusans on the defeated Athenians during the Peloponnesian War. For those whose bent is more narrowly scientific than classical, thousands (an admirably large "n") of captured Athenian and allied soldiers were placed in a quarry with black, wrinkled sides* and left there for a little over two months to see if their skin would turn black and wrinkled like their environment. Many specimens accomplished this transmogrification, but in every case, unfortunately, it was followed by death. Perhaps they were irreversibly weakened by their efforts.

I have read somewhere, Arkanis (though not in Thucydides), that during the experiment, Syracusan mommies and daddies would picnic with their children at the top of the quarry and watch this interesting experiment as it took place, so this should make a good family activity  

Good luck with both the experiment and the introduction of your kids to a timeless classic.

O.K., O.K. I know that Greek marble is typically white when cut and polished, but in the absence of any evidence to the contrary, I am assuming that the raw marble here was dirty gray with large black inclusions. Otherwise, they wouldn't have conducted the experiment, would they?


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## nasty bugger (Jan 7, 2009)

I've got my mantis' in jars with branches from the tree outside, looks like a euchlyptis, but doesn't smell like one, and the babies started brown, but some turned green with age, and now the leaves are dead and mottled brown, and the mantis' are more brown than they were, so I think they do disguise themselves to a degree.

I have a larger one in a container with an air plant, that is green and has some brownish tinges and roots, and the mantis is a not-so-lime, more of a green on it's edges,like the plants green, and brown in the other area's, like the roots and edge of the 'leaves or fronds' tone. He does appear, to me, to be blending somewhat well.


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## Christian (Jan 8, 2009)

Texture has no effect on mantis coloration. If you want to get some color effect, you should paint all the cage (including branches etc.!) in the color you are testing for. Just a piece of paper behind them isn't sufficient. Be sure that you have a control group. By the way, you should test natural colors. Start with red, blue and yellow and go to black, white and purple if you have more mantids to test.


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## revmdn (Jan 8, 2009)

How about having at least two more groups: one with the color enhancement and high humidity and one with just the high humidity (for control). I think the humidity has more to do with it, but this is purely my own personal thought.


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## Christian (Jan 8, 2009)

Humidity does influence coloration as well (the relation between the green and brown phases), but if he wants to test for color effects of the environment, he has to keep humidity (and luminance by the way) absolutely constant.


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## Katnapper (Jan 8, 2009)

Christian said:


> Texture has no effect on mantis coloration. If you want to get some color effect, you should paint all the cage (including branches etc.!) in the color you are testing for. Just a piece of paper behind them isn't sufficient. Be sure that you have a control group. By the way, you should test natural colors. Start with red, blue and yellow and go to black, white and purple if you have more mantids to test.


I'm curious if you did this test, must the paint be opaque? What about lighting? Would it have to be artificial... and inside the colored enclosure? Thank you.


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## Christian (Jan 8, 2009)

It is not important if the other factors are more natural or artificial as long as you keep them identical for all.


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## chun (Jan 8, 2009)

Katnapper said:


> I'm curious if you did this test, must the paint be opaque? What about lighting? Would it have to be artificial... and inside the colored enclosure? Thank you.


Ideally, you'd want to control for the lighting but that won't be practical for a small scale investigation, but it's probably best if you subject the experimental specimens, the mantids, to the same light source throughout the investigation. As this investigation is proposing that coloured background causes polymorphism, if this was to be done properly, then light source (light wavelength) must be taken into consideration and as a possible variable for the cause of colour variation. For instance, if fluorescent lighting was used then the wavelength of the light produced would be slightly blue and thus, the light receptors in the mantid eye would be biased towards blue (someone please correct me if i'm wrong as i have little background in physics and eye physiology).

*ps, didnt read christian's reply before posting*


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## Katnapper (Jan 8, 2009)

I guess to expand on my question... I mean if you painted the entire enclosure a certain color (all 4 sides, top and bottom), if it was opaque paint and not a see-through tint, then it would make the interior of the enclosure entirely dark... so you'd have to have a light source of some sort inside the enclosure if that were the case... no? Or else the mantids would be living in the dark all of the time, and furthermore as a result not see the color anyway?


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## Christian (Jan 8, 2009)

I get the point now. Of course you should paint it in a way that light can shine through. Either by painting only the dark parts or by using translucent colors for the screens.


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## Katnapper (Jan 8, 2009)

Christian said:


> I get the point now. Of course you should paint it in a way that light can shine through. Either by painting only the dark parts or by using translucent colors for the screens.


I see...  Thank you, Christian.


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## kamakiri (Jan 8, 2009)

Christian said:


> If you want to get some color effect, you should paint all the cage (including branches etc.!) in the color you are testing for. Just a piece of paper behind them isn't sufficient.


Why not?

The pink/other morphs we are looking for have formed in the wild without such all-or-none conditions. I don't see the benefit in testing a completely colored cage. The 100% color could introduce other environmental stress factors we are not aware of. Even for my casual test with colored post-its and pen markings, it appears that the mantises will tend to stay in areas that are green, green/pink, and pink areas over the clear deli-tub sides or the plain white top areas. Probably better to let them choose where to go...more like they would in the wild.

Just my thoughts for my 'improper' experiment!  Anyone else is more than welcome to do their own to the most exacting standards!


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## Katnapper (Jan 8, 2009)

chun said:


> Ideally, you'd want to control for the lighting but that won't be practical for a small scale investigation, but it's probably best if you subject the experimental specimens, the mantids, to the same light source throughout the investigation. As this investigation is proposing that coloured background causes polymorphism, if this was to be done properly, then light source (light wavelength) must be taken into consideration and as a possible variable for the cause of colour variation. For instance, if fluorescent lighting was used then the wavelength of the light produced would be slightly blue and thus, the light receptors in the mantid eye would be biased towards blue (someone please correct me if i'm wrong as i have little background in physics and eye physiology).


I want to apologize for not addressing your post, Chun, at the time I replied last. I wanted to... but was really tired and couldn't write or think any more at the time.

I think your idea for control of the same type of lighting is right on. I agree you would have to keep the type of lighting (different wavelenghs and hues) the same to test for the other variables. Good point.

I don't plan to do any color testing experiments myself right now. But it's interesting to me to see what results, if any, others might get.


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## Christian (Jan 9, 2009)

> The pink/other morphs we are looking for have formed in the wild without such all-or-none conditions. I don't see the benefit in testing a completely colored cage. The 100% color could introduce other environmental stress factors we are not aware of. Even for my casual test with colored post-its and pen markings, it appears that the mantises will tend to stay in areas that are green, green/pink, and pink areas over the clear deli-tub sides or the plain white top areas. Probably better to let them choose where to go...more like they would in the wild.


There are several problems arising here. First of all: the tested mantids are *not* in the wild, but under captive conditions. So you can't expect them to do what they would do in the wild. One point is that the cage as such is a small compartiment, regardless how large it is; and in most such cases space is reduced in favor of sample size. Ever asked why mantids always hang on the mesh? It's not only because they get a better grip, but because it's the highest point (away from the ground) they can reach. Particularly the arboreal species live at a certain height. So, even an understorey species like _Deroplatys_ or _Euchomenella_ perch at about 1-4 m height, that is more space than most people would allow their mantids to live in. The larger the species the more obvious this problem. And the larger the cage, the more the mantids space out in it and aren't confessed to the top screen.

The point here is: neither does the mantid behave in captivity as in the wild, nor can it choose a perch as in the wild. A typical case are the so-called flower mantids including _Hymenopus_, who would sit everywhere except on the flowering plants we are offering them.

The other important point is that color change in mantids is induced by an *overall* impression of the environment. An arborel species always has a green "forest" impression when "it looks around". A grass dwelling species is surrounded by an ocean of light green (or tan, when the grass fades). Our mantids are in a lab or at home and the only impression of the environment they get is tan or grey. Putting a leaf or a pink flower or sheet inside its cage doesn't change the mantid's impression that it lives in a brownish environment. Thus, if you want to see any effect whatsoever, you have to change the mantid's impression of its ovarall captive environment. You have to paint everything in the color you are testing for, or, filter the light in a way as it is, for instance, filtered and reflected by natural foliage.

And here the last obstacle arises: light spectrum. You cannot achieve the full spectrum of natural color changes under artificial lighting. But you get some results and they are worth testing them. In order to achieve natural color changes you have to use a greenhouse with plastic roofing (UV should pass through). You should at least try to get the best spectrum available. The terraristic sector offers some good alternatives in the meanwhile.


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## kamakiri (Jan 9, 2009)

Christian said:


> The other important point is that color change in mantids is induced by an overall impression of the environment. An arborel species always has a green "forest" impression when "it looks around". A grass dwelling species is surrounded by an ocean of light green (or tan, when the grass fades).


Well, that's oversimplifying it a bit...what about the blue sky, or the depth perception that manitses have? Painting the whole container one color will 'enclose' the mantis too much. That's the stress I'm talking about. A better example of what you're suggesting would be putting a mantis in a clear enclosure in a large room painted the target color on the lower half, blue on the upper half and have cove lighting with simulated daylighting or skylights. I can't afford that  



> Our mantids are in a lab or at home and the only impression of the environment they get is tan or grey. Putting a leaf or a pink flower or sheet inside its cage doesn't change the mantid's impression that it lives in a brownish environment.


That's too broad an example. We're talking about a species that frequently perches on flowers on 2'-4' shrubs that are normally green plus a flower color...often in the red, pink, and white range.



> Thus, if you want to see any effect whatsoever, you have to change the mantid's impression of its ovarall captive environment. You have to paint everything in the color you are testing for, or, filter the light in a way as it is, for instance, filtered and reflected by natural foliage.


Seems you've drawn you own conclusion on this. But then why would pink morph form when there are no conditions that are pink as far as the eye can see? Why does the orchid mantis evolve to be white when there is no completely white environment...but just the white blooms in a green and brown forest?


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## Christian (Jan 9, 2009)

> Seems you've drawn you own conclusion on this. But then why would pink morph form when there are no conditions that are pink as far as the eye can see? Why does the orchid mantis evolve to be white when there is no completely white environment...but just the white blooms in a green and brown forest?


Your suggestions show me that you don't have much experience in field ecology or behavioral biology. Orchid mantids aren't just pink because they have to sit on flowers. The camouflage works also without any flower in sight. You are confounding two adaptive principles here: protective coloration (the issue we are talking about) and special resemblence. The latter comprises species like leaf, stick and flower mantids. Those are "working" with a different mechanism than those species that exhibit different color phases.



> Well, that's oversimplifying it a bit...what about the blue sky, or the depth perception that manitses have? Painting the whole container one color will 'enclose' the mantis too much. That's the stress I'm talking about. A better example of what you're suggesting would be putting a mantis in a clear enclosure in a large room painted the target color on the lower half, blue on the upper half and have cove lighting with simulated daylighting or skylights. I can't afford that


You did not understand that you don't have to copy the natural environment to get an effect. You can't copy the natural environment either, so you have to simplify everything down to the effect you want to show. This is not something you can't afford.

The mantis isn't stressed by painted enclosures. Noone said that you should keep them in tiny boxes. As long as you offer adequate space, perch sites and some cover, they will do fine. Mantids are hidden in the wild, that's why it's difficult to find them. I am not talking here about the old field species facing an almost two-dimensional environment (grass and weed layer) but about arboreal tropical species in three-dimensional environment (even though the effects can be demonstrated in field species, too). Those mantids hang on the underside of leaves and the understorey dwellers among them hardly see any "blue sky". What they see is forest. Even the savanna species don't adjust their coloration to the sky but to the perch sites.



> That's too broad an example. We're talking about a species that frequently perches on flowers on 2'-4' shrubs that are normally green plus a flower color...often in the red, pink, and white range.


Where is this data from? Have you ever found an orchid mantid? They aren't good for testing this issue as they are white already. They can only switch between whitish, pinkish and yellowish. _Pseudocreobotra_ and _Creobroter_ species are better candidates and those ones usually sit on weeds, not in bushes!!

You have some romantic impression of what a flower mantid should be. Reality is often rather different from this - and more astonishing regarding the real adaptive principle of such a coloration. However, it is good to start the experiment with one of the species that switch between a green and brown phase (_Sphodromantis_ etc.). Thus, you can test which colors they are able to adapt to: just green and brown or more?


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## kamakiri (Jan 10, 2009)

Christian, I am primarily talking about _limbata_ mantises as that's all Arkanis and I are using for this. I only made *one* specific reference to the orchid mantis. Nothing to do with your entire last paragraph there.

We're obviously not communicating very well...so that's all from me on this subject.


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## Christian (Jan 10, 2009)

Noone ever mentioned _St. limbata_ in this post. If you want correct answers you should post correct questions. However, all I said previously can be tested with _St. limbata_ as well. It can be tested with all species exhibiting several color phases.


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## Notanothernickname (Jan 12, 2009)

I may have misunderstood, but would it not be better to have some mantids in a particular colour and some in a particular texture rather than all of them (apart from the controls, of course) in a particular colour and texture, because that would give two variable and make it hard to draw a conclusion as to which caused any change which may occur?

Of course, you could always test whether either has an impact, and then do some further testing to see which it is.


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## chun (Jan 12, 2009)

Will said:


> I may have misunderstood, but would it not be better to have some mantids in a particular colour and some in a particular texture rather than all of them (apart from the controls, of course) in a particular colour and texture, because that would give two variable and make it hard to draw a conclusion as to which caused any change which may occur?Of course, you could always test whether either has an impact, and then do some further testing to see which it is.


sometimes, in nature, certain morphological traits are caused by a combination of more than one variables. Good experimental design is an art, it's not as easy as most people think.


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