# Camouflage Analysis Of The “African Leaf Mantis” Phyllocrani



## chun (Aug 22, 2006)

i found this article whilst browsing through my old backup CDs, and thought it might be of some interest to people on this forum  It was written by me and julian camilo. Anyway, i hope you guys enjoy it as much as we enjoyed composing it. This article is composed with our personal experience and from other hobbyists' experience as well, along with some related lieterature. this was done when we were 15 so please excuse the lack of referencing to scientific literatures (and the lack of proffessionalism). enjoy  

*Camouflage Analysis Of The “African Leaf Mantis” Phyllocrania Paradoxa Burmeister, 1838 *

The first time you see the “African Leaf Mantis”, it is obvious why it is so called. It, like all other mantids, which fall under the “leaf mantis” category, display evident signs of crypsis. Leaf mantids come in various forms, be they crumpled dead leaves, crumpled live leaves, or smooth dead leaves. This species falls under the live and dead crumpled leaf categories. In this article we will be analysing the camouflage methods, which Phyllocrania Paradoxa utilises to remain unseen.

The first clue to the appearance of this mantis is in the name. The ‘Phyllo’ part of the name suggests something saw-like, or something sharp. The ‘crania’ part is definitely referring to its head, so if we put them together, we get some kind of “saw-head”, or “sharp head”. This is referring to the saw-like protrusion from the mantids’ head. The Paradoxa part of the name suggests double meaning (paradox), and so is probably to do with the cryptically nature of the mantid’s appearance.

Now we will look at colour. The colour of this species is one of the most varied among mantids. It ranges from a very bright green to a black with dark brown tinges. Also, unlike many species, it keeps its colour variation into the adult stage, rather than reverting to a certain colour scheme in the moult into adulthood. The variation in colour is thought to be caused by its rearing conditions, namely humidity, temperature and light intensity. Heat seems to play a rather subordinate role in determining colour. The green end of the colour variation spectrum is due to high-end humidity, and low-end light intensity. The dark brown/black end is caused by lower humidity and high light intensity. This is because the mantis changes its appearance in terms of colour to suit its surroundings. To understand the mantis’ camouflage strategy, we must first understand what it is trying to blend in to. In the rainforest, there is a thick canopy that lets little light through to the main floor of the forest. On the forest floor there are many plants and lush green vegetation which have adapted to survive on very little light. The animals and insects that wish to be here and remain camouflaged must adapt to this. In the rainforest there is a very high humidity level, and underneath the leaves where the mantis will usually perch there is not much light. This leads to the mantis becoming green in these conditions. The other end of the variation spectrum is the dark brown/black end. The plains and grasslands of Africa are also home to this species. They are not covered or sheltered by much, and so there is high light intensity, and very low humidity level. The plants here being in constant view of the sun causes them to often be very dry, and in many cases dead. This leads to the mantis having to become very dark, or just brown, to remain unseen. In some cases, species of insects which are typically brown or green, change to black. This is caused by bush fires in African grasslands, and this is often the case for mantids. It is assumed that fire melanism is an environmentally induced polymorphism, although this has never been proved. The colour of the mantids changes usually from one moult to another, if the change in conditions is drastic enough. This is because dry and ‘dead’ plants can be revitalised by rain in days, and so the mantis will be left looking very conspicuous if it does not change its colour drastically. Sometimes the change occurs over a series of moults. This usually occurs when the change in conditions is not very drastic, so the mantis changes slightly in case the change in conditions is only short, giving the mantis a chance to still remain camouflaged, but able to return to its previous colouration, should the conditions revert back to normal.

Next we will look at the features of the mantis. Both sexes of the species have a small protuberance on their heads, between the two main eyes. This is most likely mimicking the tip of a crumpled leaf. This is often curled or crumpled, and rarely straight and flat, which helps with the crypsis. Next we have the forearms. They are shaped in mostly the same way as other species of mantis. However, they are able to become tucked underneath the head and into the thorax more. This allows them to make their profile more smooth and uniform, a strategy also adopted by grass mantids. This helps as it dissociates itself from the profile and outline of a typical mantis, and more into the outline of a typical dead leaf. The thorax is plate-like, but is crumpled and bumpy, rather than flat and smooth, which looks a little like a small dead leaf, but also helps to conceal any trace of forearms when viewed from above. The wings of the mantis are narrow and fairly long. In males, they are very delicate, and cover the entire abdomen, which cannot be seen from above. The females, as ever, are more cryptic, and the sides of the abdomen have leaf-like protrusions, which extend past the sides of the wings, so that they are viewable from above. By breaking through the line of the edge of the wings, the mantis again dissociated itself from the typical mantis outlines, and becomes more like a small group of leaves, as the protruding “lobes” disrupt the outlines and make it irregular. The “lobes” are also bent and crumpled at the tips, another similarity to dead leaves. Each leg has two “lobes” or protrusions extending from them, much like Hymenopus corronatus’ petal-like extensions, but smaller, and larger than those of, say Gongylus Gongylodes. The crumpled and twisted protrusions from the legs make the legs seem like small twigs with a few small dead leaves on them. Even though this is not so apparent and convincing when the mantis is perched conspicuously on your hand or other place, it is very effective when in the jungle amongst all the foliage.

The males of this species are not nearly as cryptic as the females, as is the case with many species. This is partly due to the fact that males have less need to remain unseen. They are the only ones who fly in this species, as the adult females are too bulky and heavy, and their wings are not as large. The females tend to stay in much the same place in the wild, occasionally releasing pheromones to attract a mate, and maybe moving around to catch prey, although they are mostly sit and wait predators. The male is the one who must do all the chasing and flying in order to find a mate. Because the female is less agile, and thus less able to escape a predator attack, it must use another method to remain alive. Thus, it is more cryptic to make sure it is not seen in the first place, because it has little chance at surviving when it is seen. The male is able make long jumps helped by some flapping of the wings, and also capable of free flight. His ability to escape means he does not need to be so cryptic. Also, the male does not live too long, and so if he is eaten or killed because of his lack of crypsis, then it does not matter as much. The male’s only purpose in life is to secure his genes in the next generation, and once this is done there is not much need for him to remain alive, unless more females are to be mated. The females however, live for much longer, and once mated still have the task of producing as many viable and properly formed ootheca as possible, and the females can often live for many months if not eaten or killed, because the high level of crypsis helps to keep it unseen. To maintain the projection of a dead leaf, Phyllocrania paradoxa has a strategy to come round this. They maintain this projection by egesting more often than most other mantids to basically lose weight, so the abdomen would not be bloated and ruins the mantid’s attempt to be as cryptic as possible.

Another strategy this species employs to remain unseen is to play dead. As the nymphs get older, this strategy features in a higher percentage of the total defensive strategies, and is very common when adults. When feeling sufficiently threatened and with no other option, the mantis will jump, pull all its legs tightly inwards, and just remain in this position. In the wild, this could mean a large fall to the forest floor, by which time the predator or threat will have lost sight of the mantis. If they have still followed it to the floor, they will find it hard to make out the mantis amongst all the dead leaves, which litter the floor. Also dead preys do not appeal to predators. The mantis often lands on its back, and does not move until it feels the initial threat is no longer present. It then rights itself and begins to either make its way to its original position or find a new place to perch.

*Written by Julian Camacho and Chun Siew*


----------



## Johnald Chaffinch (Aug 23, 2006)

great info!

i was wondering does anyone know where the simple eyes on Phyllocrania paradoxa are? i've taken some macro shots of their heads but i cant see any sign of extra eyes -

http://i24.photobucket.com/albums/c41/john...ys/STA60002.jpg

http://i24.photobucket.com/albums/c41/john...deys/000000.jpg

also, i've noticed slight shade variations from one day to the next in this species, maybe it was just because the mantis was drier though i cant be sure


----------



## chun (Aug 23, 2006)

it's quite hard to find it on those photos, but in picture like this you can see the ocelli pretty clearly between the 2 antennae

http://www.dynamicbalancingtaichi.co.uk/MantisHead.jpg


----------



## Johnald Chaffinch (Aug 23, 2006)

yeah, i know that's the case with other species.

where's the extra eyes on Phyllocrania paradoxa ?


----------



## Rob Byatt (Aug 23, 2006)

Hey John,

the 'extra' eyes, known as ocelli, are situated on the front of the head (antero-dorsally) between the eyes, forming an inverted triangle.

Hope that helps !


----------



## Johnald Chaffinch (Aug 23, 2006)

cool ,thanks. i still cant see them though, they must be totally invisible with this species


----------



## sean (Aug 24, 2006)

take a look at some of the head shots of p paradoxa on this site...

http://www.photo.net/photos/siwanowicz

i think you can see them on one or two pics.


----------



## chun (Aug 24, 2006)

you can see it quite clearly in this picture

http://www.photo.net/photodb/photo?photo_id=3927705

despite viewing these pictures so many times, i am still in awe everytime i see them! truly beautiful pictures!


----------



## Johnald Chaffinch (Aug 24, 2006)

thanks, i was starting to think they didnt have them.

yeah they are some of the best insect photos i've ever seen


----------

