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An Alpine chough in flight at 3,900 m (12,800 ft). Organisms can live at high altitude, either on land, in water, or while flying.Decreased oxygen availability and decreased temperature make life at such altitudes challenging, though many species have been successfully adapted via considerable physiological changes.
Typically mammalian skin consists of collagen fibers arranged in a felt-work pattern, with no preferential fiber orientation. [12] However, the structures of skin in bats, birds, and gliding lizards are very different from those of typical mammalian skin. The structural arrangement of the fibers within bat wing skin enables the bat to act like ...
Amniotes are distinguished from the other living tetrapod clade — the non-amniote lissamphibians (frogs/toads, salamanders/newts and caecilians) — by the development of three extraembryonic membranes (amnion for embryonic protection, chorion for gas exchange, and allantois for metabolic waste disposal or storage), thicker and keratinized ...
Higher eumelanin levels also can be a disadvantage, however, beyond a higher disposition toward vitamin D deficiency. Dark skin is a complicating factor in the laser removal of port-wine stains. Effective in treating white skin, in general, lasers are less successful in removing port-wine stains in people of Asian or African descent.
Compared to mammalian skin, that of reptiles is rather thin and lacks the thick dermal layer that produces leather in mammals. [97] Exposed parts of reptiles are protected by scales or scutes, sometimes with a bony base , forming armor. In lepidosaurs, such as lizards and snakes, the whole skin is covered in overlapping epidermal scales. Such ...
Chronobiology – field of biology that examines periodic (cyclic) phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. Dendrochronology – study of tree rings, using them to date the exact year they were formed in order to analyze atmospheric conditions during different periods in natural history.
Human skin shows higher variation in colour than any other single mammalian species and is the result of natural selection. Skin pigmentation in humans evolved to primarily regulate the amount of ultraviolet radiation (UVR) penetrating the skin, controlling its biochemical effects. [17]
The word skin originally only referred to dressed and tanned animal hide and the usual word for human skin was hide. Skin is a borrowing from Old Norse skinn "animal hide, fur", ultimately from the Proto-Indo-European root *sek-, meaning "to cut" (probably a reference to the fact that in those times animal hide was commonly cut off to be used as garment).