| A fossil of a leaf-imitating insect from 47 million years ago bears a striking resemblance to the mimickers of today.
The discovery represents the first fossil of a leaf insect, and also shows that leaf camouflage is an ancient and successful evolutionary strategy that has been conserved over a relatively long period of time.
Scientists led by Sonja Wedmann of the Institute of Paleontology in Bonn, Germany, unearthed the remains at a well-known fossil site called Messel, in Hessen, Germany.
The 2.4-inch-long insects had the physical characteristics similar to the oblong leaves of trees living there at the time, including Myrtle trees, legumes, such as alfalfa, and Laurel trees.
It also shared features with modern insect relatives in size, shape, and the designs used for camouflage. For instance, the fossil had foliage-like extensions from its abdomen.
During the day to hide from overhead predators, a leaf insect can stay still for long periods of time, tucking its head into its body to strengthen the leafy camouflage appearance. The fossil insect apparently did the same, as the scientists found its fore legs were curved and formed a notch where the insect’s head could be inserted.
At night, when the nocturnal bugs are active they rock back and forth like a leaf fluttering in the wind.
The camouflage appearance has changed little since the Eocene times, suggested the researchers in this week’s issue of the Proceedings of the National Academy of Sciences.
Sea fauna has the same camouflage phenomena and in the same wide dimensions: fishes, lobsters, and other organisms living at bottom level due to its color and uniformities of the surface of the body, it is very difficult to distinguish them from the bottom where they live; the similarity increases more in some cases with the capability to change its color depending on the color of the bottom, for example, Cephalopoda molluska, some fishes and lobster types. This action takes place automatically, controlled generally by the eye retina. Light irritation is transferred to pigment cells with spreading fibers — chromatophores, which are capable to reduce, expand and put a halo not depending on one on another by creating the multiple color combinations. The mechanism of similar phenomena and Lyob is determined as tele photography of an image appearing on the retina, onto the surface of retina, onto the surface of body and a diffusion transfer from the retina to the skin.
One of the excellent adaptations in color is noticed among the pelagic animals of the sea, which are freely swimming in the water: among them only there are many shapes not having any color with glass transparent bodies. For examples, Salpidae, ctenoids, some mollusks and worms and even fishes (larwa of sea eels Leptocephalidae), for which all the tissues of the body, nerves, muscles, blood are made in a transparent form like crystal.
Adaptations to known conditions of illumination, playing of the light and dark are also noticed among the different cases, the so called harmonic painting. Animals, which in abnormal conditions of life are with bright colors and heterogeneous, actually may tone and blend with the color of their surroundings. Bright, dark and yellow cross sectional stripes of a tiger hides it from the eyes in bushes of rocks and bamboo, where it lives, by merging with the play of light and dark of the vertical stems and the leaves hanging down around it. The rounded spots on the skins of some wild animals have the same purpose: fallow deer (Dama vulgaris), panthers, and ocelot; here these spots match with rounded patches of light, with which the sun plays on the leaves of trees. Even the heterogeneous skin of the giraffe is not an exception: at some distance, it is very difficult to identify it from the overgrown lichens of old trunks of trees, between which it is pastured.
We can notice similar phenomenon with bright, heterogeneous colored fishes of the coral reefs.
Camouflage and Mimicry of shape:
Finally, there are cases when animals obtain an extraordinary similarity not only in color but also in shape with individual objects among which they live. This is called imitation, M. especially many examples we can find among insects. The caterpillar of the butterfly-geometrids (Geometridae) lives on branches of plants, with which it is similar in color and has the habit to expand and hold firmly its body in the air using the rear legs. In this relation, they appear as small branches of plants, and the result of which is it is very difficult to notice for even experienced eyes. Other caterpillars have similarities with the excrements of birds and with overgrown catkins of the birch tree.
Tropical orthopterous insects from the Phasmidae family have wonderful adaptations: with their color and shape of their body they imitate — some dry sticks of several vershoks of length. When butterflies of the Kallima kind in the Sunda islands with bright colors on the top of the wings are landed on a branch and their wings are folded, it looks like a flaccid leaf: with a short growth of rear wings the butterfly rests in branch, and it will have a similarity with a leafstalk; the figure and color of the rear side of the folded wings are very similar to the color and venation of a dried leaf because of which it is very difficult to differentiate the butterfly from leafs. Similar camouflage examples are known from sea fauna; small fish from the family of sea Prosopium cylindraceum, Phillopteryx e ques, which lives on the banks of Australia, owing to the multiple tape type and thread type skin growths of the body, it has a similarity with algae, among which it lives. It is obvious what type of benefit the animals get from these types of camouflage adaptations in avoiding their enemies. |
[ Camouflage shapes and coloring was successful evolutionary strategy for many insects, which allowed them to blend with environment and hide from predators. ]
