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by: Marijcke Jongbloed


  I was watching a documentary video that was shot by remote control camera on Jebel Samhan in Southern Oman. The scene was a steep hillside with a narrow track that curved around some boulders. Suddenly there was roar that seemed to come from one of the boulders. There was an answering call from the valley below. The ‘calling boulder’ turned out to be an Arabian leopard, so well camouflaged that even I, forewarned as well as familiar with the leopard’s appearance, had not detected it.

  Where African leopards have a background colour that fits the browns and yellows of their habitat of grass and trees, ‘our’ leopards have perfect camouflage for their habitat of grey rock and dark shadows.

  Most wild animals can blend in with their surroundings – something that humans never seem able to do! The general colour scheme in mammals is of a mixture of grey and tan on top, lighter brown on the flanks and creamy white underneath. Few wild mammals have any pure white patches of hair, unless they live in the arctic. The only exception to this rule is that some species have a bright white patch on the underside of their tail, called a flag. This spot is visible when the tail is raised and is mainly meant as a guide for their young to follow. When the animal does not want to be noticed, the tail will be kept down. In other species the tip of the tail takes on the flag function and can be white, as in sand foxes.

Towerhead grasshopper in varied vegetation

  Reptiles that live closer to the ground have earth colours, sometimes patterned with black stripes or spots that can make them disappear in a clump of grass. Most people have heard about the sand viper that hides under the sand as it lies in wait for passing prey. Sometimes you can find the print of its hiding place if you are out in the early morning before the wind has wiped out the signs in the sand. The sand viper is sand coloured and would be hard to spot even if it did not hide under the sand. Its cousin, the carpet viper, is darker coloured with a black and sometimes white pattern, which provides good camouflage when it hides in a bush or between rocks. These snakes do not need to hide to avoid being killed, but they need their camouflage so that their prey does not notice them until they are close enough to be caught.

  The true masters of camouflage, however, are those at the bottom of the food chain. They need to be able to ‘disappear’ in order to stay alive, unless they can instil fear by signalling their being poisonous or evil tasting. This latter ability is less widespread. In the UAE it occurs for instance in the Diadem butterfly. The male is black with some white and blue iridescent spots on its hind wings. The female looks entirely different, namely like an exact copy of the Plain Tiger butterfly. Any bird worth its salt knows to avoid Plain Tigers because they taste terrible. By mimicking the appearance of the Plain Tiger the female Diadem profits from this instinctive knowledge.

  Most insects have a less complicated manner of survival. They hide. Or they try to look like something else. One of my favourites is the caterpillar of a small moth that builds a cocoon consisting of small twigs around its vulnerable body. When it feeds on its food plant (Fagonia spp.) it looks like a small clump of the buff coloured Fagonia thorns – a foolproof protection against predators. In fact, I would never have imagined that something alive was inside the small structure, when I first came across it, if I had not read about something like this just the day before. There is a gastropod in the sea that has a similar strategy: it adorns its shell with sand grains, bits of seaweed and other debris that it finds, so that it looks like a (sometimes moving) bit of seabed.

  Another interesting feat of camouflage occurs with the caterpillar of the already mentioned Plain Tiger butterfly. When it is very young it is black with an irregular shaped white spot right across the middle. When it sits on its green food plant, it is very conspicuous. Not good for a small morsel like that, you might think. But what does this slow moving creature look like: a small bird dropping. And which bird would think of eating a dropping? Later on in life the caterpillar takes on very brilliant colours: white, black and red. Now they are warning colours: “Don’t eat me, I don’t taste nice”. If threatened, it can give a warning spurt of its evil-tasting juices from some glands just behind its head. In the wadis you often find these caterpillars on food plants that are members of the carrot family. If you irritate the caterpillar very lightly - with a blade of grass for instance – it squirts some drops of the most intense carrot-smelling fluid that would only appeal to a rabbit.

  The same colours of white, red and black are used by a small day-flying moth, but not as warning colours. It seems unlikely that black and red spots on a white background could make a flying insect disappear in a world of sand and small green bushes. But I found out that it is perfect camouflage for this moth, Utetheisa pulchella, when I tried to photograph it. I would follow it as I saw it flitting from one bush to the other, taking good notice of where it landed. Then creeping up to it slowly with my camera at the ready, I would never see it in time to catch it in repose. Its coloration made it blend with the sand so well, that the only times I managed to take a picture of it were when it landed on green vegetation. It made me reflect on what sand is made up of - orange, black and cream coloured grains! The caterpillar of this moth must taste bad, because it advertises the same red and blacks on a background of such bright silver that it even reflects the sunlight!

  Praying mantises and grasshoppers are also very good at disappearing into their surroundings.

  Stick insects are in the same family and are represented by several species in the Emirates. They conform to their name – they look like jointed twigs as they climb around in the dun-coloured desert vegetation.

  A close cousin of theirs is the Towerhead grasshopper (Truxalis procera). The first one I saw sat in a clump of drying grass – still green near the roots but turning yellow at the ends. The insect was exactly the same: green near the body turning brown towards the end of its legs and antennae. Later I saw the same insect in different surroundings – a light brown one on light brown rocks, a dark green one with black spots in a dark green bush with black shadows.

  I am not sure if these are all the same species, that turn colours like a chameleon, or if there are several different species around.

  Once I was taking photographs of the pretty flowers of the Tamarix bush, when I noticed a rather beautiful praying mantis on the bush. It was a young one, with its abdomen still curved upwards. Its coloration was exactly the same as the colour of the Tamarix flowers, and the unusual shape of its body fitted the irregular shape of the sprays of flowers exactly. When the film was developed I noticed that the insect was present in the first picture I had taken of the bush, long before I had noticed what was living on the bush. I had taken it for one of the flowers!

  The absolute champion of camouflage was a spider I found on a sandy plain some years ago. If it had not moved I would never have seen it at all. I took a picture and when it was developed I thought I had missed it after all. But looking very closely I could just make out the eight black eyes on its head and the long curves of its legs – but only because I knew it had to be there. I should have taken a second picture after placing it on a dark background.

  One tiny camouflaged insect that occurs locally is a hunter and not a prey. Just like the snakes mentioned before it lies in wait for prey to come close enough so that it can pounce and catch it. This is the crab spider (family Thomisidae) that sits on flowers and has the same color as the flower petals, so that it is almost invisible. I have seen them yellow on sunflowers (only visible when they happen to be sitting on the heart of the flower), white on the flowers of a blossom, dusty green on similar-colored Caralluma stems in the desert, and striped red and yellow on the petals of the Gaillardia in my garden. As happened before with the Tamarix mantis, I once photographed a bee on a white blossom and did not notice the crab spider just about to pounce, until after I saw the developed picture!

  With such little miracles around us all the time, I can never understand why anyone would spend their time reading science fiction!

   

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