Why do all cats have white whiskers?

Why do all cats have white whiskers?
Nearly all felines appear to have white whiskers. Normal cat hair comes in various colors — black, white, orange...  But whisker hair differs from fur.  It’s thicker, the roots delve deeper and a dense, tough bag filled with blood vessels and nerves surrounds the whisker.  For some reason, though, the cat whisker usually does not access (or, possibly, retain) melanin (the dye that colors hair) and, therefore, cat whiskers are white. When a cat is an embryo, the whiskers and pigment cells form in the same skin layer.   A whisker starts as a single ring of skin cells at the root.  Soon a new ring of skin cells develops at the root, and this new ring pushes the older ring up, toward the skin surface.  In this fashion, ring-by-ring, a whisker is born — formed of concentric rings of skin cells.  But, as new cells push the cone of skin cells upwards the surrounding tissue squeezes the cell cone inward and the skin cells die.  Eventually the cone emerges from the skin as a whisker, composed of dead skin cells which have no pigment so they are white.

Why do rabbits twitch their noses?
A rabbit twitches his nose to detect the faintest odor that might mean danger. He twitches it constantly — 20 to 120 times a minute — to expose more sensing pads in his nose. With his 100 million receptors (compared with a mere 5 or 6 million that we humans have), he’s well equipped. Rabbit noses twitch rhythmically and only quit when they are totally relaxed, probably asleep.