Download Animal Camouflage by Adolf Portmann PDF

By Adolf Portmann

The rugged define of a mountain height appears like a human face; the markings on a moth convey a cranium and crossbones. Mere coincidences we are saying, and brush off the problem as one other freak of nature. but if we come upon an animal that appears like a leaf or a spray, we commence to ask yourself. This likeness has to be greater than chance--it needs to play an enormous half within the animal's survival. This brings us immediately to the crux of our challenge: the functionality of outward appearances.

We have all visible bugs which are the colour of bark and brooding pheasant hens whose feathers look like the fleeting shadows in their nesting floor. We could have chanced upon a moth whose basically defense is the coloring that makes it resemble a wasp. every one of those animals pretends to be anything it isn't, and it does this with a purpose to live to tell the tale. sleek armies use camouflage to guard their infantrymen, weapons, ships, and army installations; the result's facts optimistic of the protective price of such options. The reader aren't shocked then, if we inform him that our topic has performed a favourite half in all discussions concerning the foundation and the evolution of dwelling organisms. Charles Darwin was once one of many first to emphasize the significance of camouflage, and because his day the topic has shaped one of many strands of organic thought.

This isn't really to claim that the professionals all agree. What a few decide to clarify as camouflage, others describe in altogether diversified phrases. a bunch of experimenters has got down to turn out many of the theories, yet regularly with ideal clinical detachment. the matter of mimicry, particularly, has develop into a veritable no man's land of organic battle.

These are issues our ebook will discover. Casting our look over an enormous canvas, we will try and hint the
meaning of a few of the colourful brush strokes that went into its portray.

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Additional resources for Animal Camouflage

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Publication Year: 1959. Page Number: 54. 52 title rigid posture, the open beak and eyelid resembling cracks in the bark, and the wings and tail looking like part of a branch ( Fig. 64, left ). The bird seems to be part of the tree on which it perches, and it keeps its rigid posture even during brooding. Resemblance to branches and to bark may be restricted to the most helpless--the earliest--period in a bird's life. Thus, the Indian tree swift (Hemiprocne longipennis), which is a powerful flier, has no need for protective coloration once the wings are fully developed.

51 ). The deception can be increased by further modifications. Thus, the deadleaf butterfly (Kallima), for instance, displays transparent or white spots that look like fungi, and some South American grasshoppers exhibit skeletonized leaf effects, fungus growths, and typical leaf discolorations. Some wings even resemble leaves that have been bitten through by caterpillars ( Fig. 52 ). Only the careful examination and comparison of both fully extended wings will reveal the symmetrical arrangement of these indentations.

The thorax and the first abdominal segment become mightily inflated and two eyespots suddenly make their appearance. The three pairs of legs in the center of the "snake's head" are pressed close to the body, and the head keeps rearing up and down until the caterpillar is reassured and returns to the resting position. The whole process of inflation and rotation involves a very high degree of behavioral organization. An African FIG. 77. A caterpillar of a South American hawk-moth (Leucorhampha triptolemos).

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