What kind of hair serves as insulation for a mammal

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Create your free OpenLearn profile. Course content Course content. Studying mammals: A winning design Start this free course now. Free course Studying mammals: A winning design. Question 12 From your general knowledge, what characteristic is shared by those tropical mammals that have little or no fur? Answer In general, they are very large animals - think of the rhinoceros and the elephant. Figure 4: Clutton-Brock, J.

Figure 4 A vertical cross-section of the skin of a typical mammal. The upper outer epidermis consists of tough, dead cells. The inner dermis has glands and nerve endings that impart sensitivity to touch. View larger image. Figure 5: Willmer, P. Figure 5 The temperature at different sites within and outside the fur of a mammal adapted to arctic life. The temperature at the surface of the epidermis is close to that of deeper tissues below the dermis, i.

The close match between these measurements shows that nearly all the insulation is provided by fur, notably by the air trapped between the hairs. Previous 5. Next 7 What's special about placental mammals? Print Print. Take your learning further Making the decision to study can be a big step, which is why you'll want a trusted University.

OpenLearn Search website Back to top. Our partners OpenLearn works with other organisations by providing free courses and resources that support our mission of opening up educational opportunities to more people in more places. The top photo shows a variety of colors. Detail bottom photo reveals patterns of cuticular scales. Moles live underground and are subjected to dirt and water. Each hair is made with a broad spatulate shield region tip. If wet, these shields stick together and help prevent dirt or water from penetrating the fur to the skin.

In a burrow, a mole may have to back up if it comes in contact with a hard object. The resulting change in direction of the hair could allow dirt to fall among the hairs.

As an adaptation against this, there are several thin areas strictures , which allow the upper part of the hair to move without disturbing the basal region. Shields and strictures both can be seen in this photo. The structure of mole hair makes it so soft that it is the namesake of a bandage called "moleskin.

The medulla in river otters fills about one-third of the shaft width. Note the pigment in the cortex brown flecks. In the beaver, the cortex fills most of shaft. In fact, the medulla may be absent, very thin and sometimes broken , but at most only about a third of the shaft width. All three conditions can be seen in hairs in the photo.

In felids, the medulla is wide and typically vacuolated. The vacuoles are various sizes and the shape of a spindle, or football. We do not know when hair evolved, as it is usually not preserved in fossils. Pits in the fossilized rostrum of the some Cretaceous therapsids may be an indirect indication of the presence of vibrissae McLoughlin, ; if so, these provide the first direct evidence of hair.

The small body size i. So it is likely that these animals had hair, and most reconstructions of them show their bodies covered with fur e. But was insulation the primitive function of hair, the reason why it originally evolved? Insulation is the most conspicuous and perhaps the most universal function of hair in modern mammals, but hair doesn't serve as effective insulation until it is fairly well developed as pelage.

It may be that the first hairs evolved as sensory outgrowths between the scales of some ancestral therapsid, and only later took on the function of insulation. DeBlase, A. A manual of mammalogy. Second Edition. Brown, Publishers. Dubuque, Iowa. Mayer, W. The hair of California mammals with keys to the dorsal guard hairs of California mammals. American Midland Naturalist, Miles, W. Studies of the cuticular structure of the hairs of Kansas bats.

Search, Univ. Kansas Publications, Pough, F. Heiser, and W. Vertebrate Life. Third Edition. Macmillan Publishing Co. Savage, R. Mammal Evolution, an Illustrated Guide. Facts on File Publications, New York. Teerink, B. Hair of West-European Mammals. Cambridge Univ. Press, Cambridge. Vaughan, T. To cite this page: Myers, P. Espinosa, C.