Why do we get Goose Bumps when it is cold? Goose bumps are a vestige from the days when humans were covered with hair. When it's hot and you need to cool down, little muscles at the base of each hair relax. Your hair becomes relaxed. Your sweat glands pump out body heat in sweat. Your blood vessels get big to take more heat to the skin to get rid of it. When it's cold, the arrector muscle pulls the hair up. The duct to the sweat glands gets small to conserve heat. Our blood vessels also get small to save heat.
Why Do Bats Hang Upside Down? Because they need to put their feet up. Since bats are the only mammals who can fly, with wingspans ranging from 6" to 6', they failed to make great strides in the walking-about, or in the standing departments. Their legs and feet are simply not strong enough to support these functions for great lengths of time. For this very reason, bats, when in their bat caves, or roosting in trees, take the weight off of their tired limbs by hanging upside down.
Why is the sea blue? There are two reasons for the color of the sea; both of them contribute to the answer. A. The sea reflects the sky: you have probably noticed that the sea is not very blue-looking when the sky is overcast. Water reflects and scatters the light that strikes it; this is shown by the fact that you can see your reflection in puddles. When the sky is brilliant blue, the sea is also, because it reflects the blue of the sky. B. The sea refracts light just as the sky does. Blue light is more easily bent, or refracted, than red light; thus, light refracted back from the surface of the sea appears blue. Furthermore, when you are underwater the water around you appears blue because more blue light is scattered back to your eye than red light.
Why do we get hiccups? When you hiccup, your diaphragm involuntarily contracts (the diaphragm is a dome-shaped muscle that separates the chest cavity from the abdomen. It plays an extremely important role in breathing.). This contraction of the diaphragm then causes an immediate and brief closure of the vocal cords, which produces the characteristic sound of a hiccup. What actually causes the hiccup is difficult to say - in most instances, there is no obvious cause. Attacks of the hiccups seem to be associated with a few different things: eating/ drinking too fast or being nervous and excited.
Why is some hair curly and some hair straight? Hair is curly or straight, depending upon the number of disulfide bonds between hair proteins found in the hair shaft. The greater the number of links, the curlier the hair, and the fewer the number of links, the straighter the hair.
Why do we have eyebrows? Those tiny, little hairs above our eyes play a very important role in keeping moisture out of our eyes. Just like an umbrella keeps our bodies dry from the rain, our hairy eyebrows keep our eyes dry from rain or sweat.