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Why Don't Penguin's Feet Freeze?

And other Last Word questions from

New Scientist magazine

Grey is default colour of hair. Youthful colour comes from pigment cells at base of each hair follicle. As you age, these cells die and stop producing pigment.

'Photic sneeze': response to bright sunlight, affects up to a third of population, inherited. Possibly because reflexes of eyes and nose closely linked (when we sneeze our eyes close and water). Has been recorded since Francis Bacon 1635.

Penguins feet don't freeze, Leah, because they have an unusual blood circulatory system, and because they have unusual control over the amount of blood flowing to their feet. The circulatory system is unusual in that there are many small blood vessels in the legs which lose heat to the veins carrying blood back to the heart, so that little heat is carried down to the feet. And penguins can, like humans, restrict the flow of blood to extremities (which is why our hands go white when cold). Net effect is to keep feet just enough above freezing point to avoid frostbite.

More books on Animals

Ants can survive in microwave because 'waves make hot and cool patterns (the turntable provided to even these out). Ants can use the cue to move to cooler areas. And, the floor tends to be cooler than rest of interior.

Tiny insects don't get knocked out of the air by falling raindrops because the drops create small pressure waves which push the insects aside.

Bird dropping are white because they are not crap, but (solid) uric acid. Animals can afford to cart around enough water to dilute their urea, birds cannot. Also, growing in eggs means don't want to produce water soluble toxins. An alternative answer suggested that birds use the white paste as a way of keeping track of successful hits on cars.

The black mould that infests tile grout can't be removed with household cleaners or bleach. Try garden fungicides, a dilute zinc sulphate solution, or potassium permanganate crystals.

Counter-intuitive, but hot water often freezes faster than cold water. Probably because hot water improves thermal contact between container and ice of the fridge, with the circulation removing the heat faster. (The question was first raised in 1969 by a Tanzanian student who claimed, to widespread scepticism, that warm ice cream froze quicker than cold.)

Superglue doesn't stick to the inside of the tube because water (vapour) is excluded (which is also why you don't use too much - air and water have to reach all the glue for the bond to take).

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