The "Pearl Crack" Experiment

[Christian]

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.

 

[kamakiri]

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?

 

[Christian]

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?

 

[kamakiri]

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.

 

[Christian]

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.

 

[Notanothernickname]

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.

 

[chun]

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.