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MAMMALS

Started by Traditionalist, October 25, 2011, 03:18:01 PM

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Traditionalist



Photo by kind permission of Peter Palms.

Mammal hair or fur grows in cycles and actually goes through three separate phases: anagen, catagen and telogen. In the anagen phase, hair is actively and continuously growing. Afterwards, hair goes through a short period of growth recess (catagen) and enters into telogen in which hair stops growing.

Hair and fur also "wears" constantly, and is shed and replaced at various intervals.

The exact control of the hair growth cycle in mammals is still not fully understood. Under normal conditions, it is predominantly controlled by photoperiod. Various animals in northern climes shed mainly in spring and autumn ( fall) . Other factors such as genetics, nutrition, and hormones also affect hair growth cycles.

Hair and fur are the same substance, ( mainly keratin). How they form, and their resultant properties are the result of genetic programming and environmental factors.

The terms "hair"and "fur" are technically completely interchangeable.

http://en.wikipedia.org/wiki/Hair

http://en.wikipedia.org/wiki/Fur

"Underfur" is the crinkly soft fur close to an animals skin. Often also referred to as "down". Mainly for insulation.It often varies in colour according to location on the animal, as does the guard hair, although some animals have "single colour" fur.Also, many animals have very specialised fur. Mole fur for instance is "unidirectional".

Depending on the animal, and the location of the fur on its body, there may be little or no underfur present. In some locations, there is underfur, but no guard hair, and variations of these combinations are also extant.

"Guard Hair", is the long hair which grows through the underfur, gives the animal protection, waterproofs it where required, and also defines its visible colour. However, the hair may vary considerably in colour along its length, and acording to its location on the animal.The tips might be white, and the base black or brown etc. Or various mottling or barring be apparent. The guard hair might be dark brown, and the underfur blue, or white, for instance.

There are various ways of removing hair from the skin, depending on what it is, and what you want to use it for. For many furs simply cutting it off with scissors works well. For other furs, various tools are useful, like a dubbing rake.For a lot of things, I like to just pinch the fur out with my thumb and fingernail. This only works if you take SMALL! Pinches, and you need a little practice as well, in order to avoid making a mess of the skin.One may also use good solid tweezers to remove hair.

Feathers have evolved to enable flight, among other things, and many of them have peculiar aerodynamic properties, even single fibres or bunches of fibres. Many flies dressed with feathers, either slips or bunches, will "Helicopter", most especially if they are not very carefully balanced in size and shape. The weight distribution when flies are dressed "upside down" aggravates this propensity, and will often hopelessly twist and damage a fine tippet after a couple of casts. With few exceptions, feathers have interlocking fibres. like tiny zip fasteners, and these "catch the wind" It does not matter much what you do, this will always happen. Also, when on the bird, feathers are constantly preened to keep them in order, and reasonably waterproof. On water-birds this is absolutely vital. If you degrease a water bird, it becomes waterlogged immediately, sinks and drowns. This is why the major bird kills by oil spills are not caused by the oil itself, although this is shocking enough, they are caused by the detergent used to fight the spill, which degreases the birds, and so they drown.

Fur and hair have not evolved to enable flight, otherwise pigs, and a host of other things might fly! They have evolved primarily to keep their bearers warm and dry. Of course there are specific hairs with specific properties on fur bearing mammals, but not in the same manner or diversity as with feathers. Also, and of primary interest here, is the fact that hairs and furs have no interlocking fibres. This means that air moving over them merely goes "through" a bunch, "over" a clump, or " around" a single fibre. The hair does not offer resistance in any specific direction, and so wings and similar things on flies which are made from it don´t "helicopter".

There are some exceptions. If one makes the wings too dense, or completely unbalanced ( One heavy wing and one very light one) then they may twist somewhat, but still not as badly as feathers, and this is in any case then a design fault, and not the fault of the material. This also mainly occurs on "stiff" hairs like deer hair and similar. Which is mainly why I don´t like deer hair for these flies. It is also far more difficult to use. Of course it works, and so do feathers, but not as well. A steam engine works very well, but I bet you drive a car with an internal combustion engine?

That is the basic explanation. One could go on at length about various properties here, but it would not really serve any useful purpose.

TL
MC

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