The colors come from their skin playing with light.

Chameleons have the ability to change the color of their skin. And, researchers at the University of Geneva have uncovered the secret.

The chameleon’s skin is made up of two layers. The bottom layer is yellow. The top layer has tiny crystals inside it that play with light.

When the male chameleon is relaxed, the crystals in the top layer of the skin are close together. White light, which contains all the colors of the rainbow, shines onto the skin, but only blue bounces back from the top layer. This color combines with the yellow color from the bottom layer to make green.

This phenomenon of creating colors with patterns is what scientists call structural color. Structural color is pretty common in the animal kingdom. Many insects (beetles and butterflies) and birds (peacocks) create color this way. Light shines onto the patterns and only certain colors come off. You can think of the skin as tiny mirrors that select the colors that will be seen.

Structural color occurs in everyday life too. If you look at a soap bubble, you’ll see hints of color. Or if you look at the bottom of a CD, you’ll see hints of color too. Both the soap bubbles and CDs are clear, but the patterns that are on their surfaces play with light to create color. Next time you are at the gas station and see oil on the ground, you’ll see bands of color. This is structural color at work too as the film goes from thick to thin.

When the male chameleon gets angry or wants to attract a mate, it changes the distance between the crystals in its skin. This time when white light shines on the skin, only red bounces back. And that red color combines with the yellow from the first layer to make orange.

Interestingly, the tiny crystals in the skin are too small to see with the human eye. They are a nanometer in size. A nanometer is equal to one-one hundred thousandths of your hair. To find them, researchers had to take a small sample of the chameleon’s skin and measure it with a special microscope. Scientists took samples when the chameleon was relaxed and then again when it was agitated.

Now, researchers are now trying to find out how chameleons know the change the distance between the crystals. And, engineers want to use these patterns to make computer screens with less glare.

What there is no camouflaging is how clever chameleons are.

Without your nose, the world would be pretty tasteless.

Try this simple experiment: Hold your nose and put a jellybean in your mouth. Chances are you can taste that it is sweet, but you cannot taste the exact flavor. However, if you let go of your nose, you’ll be able to taste the exact flavor of the jellybean. This is because your nose is key to tasting food.

When you think about tasting food, you usually think of the tongue. Your tongue is a sensor. It has thousands of taste buds that can sense sweet, sour, salty, bitter, umami and fat. Umami (said: oo-mommy) is a savory taste, which can be found in meats, cheeses, and soy sauce. Some scientists believe there is a six taste for fat too. Each one of your taste buds has chemical sensors. More precisely, your nose can sense chemicals for sugar, acid, salt, complex repulsive tastes, savory flavors, and fat content.

However, foods would be pretty boring with just those flavors. This is where your nose comes in. Your nose can sense over a thousand different flavors. These flavors are detected as they pass through the nasal cavity, but also as they travel from the back of the mouth up into the oral cavity.

When you are congested or have a cold, you cannot taste food because the flavors cannot get to your nose’s sensors. But, this eventually clears up. However, the inability to taste food does not clear up for the elderly. The sensors in the nose become less effective with time. This is why it is hard for the elderly to detect if milk has gone bad or to taste the flavors of their favorite foods. Fortunately, scientists and inventors are coming up with schemes to help keep food flavorful for those in their golden years.

So use your nose and taste all the wonderful flavors out there  …  while you can.

Salad might be one way to reduce our dependence on oil.

Every year 2 billion tires are sold. Each tire is made from 7 gallons of oil. The oil, which comes from fossil fuels, is converted to make the synthetic rubber. Many are worried about this way of doing business because it isn’t sustainable.   What is needed is another source of rubber for tires.

Enter Lettuce.

Scientists at the University of Calgary in Canada found another source of rubber and that is lettuce. Lettuce makes natural rubber. Dr. Dae-Kyun Ro found that lettuce makes rubber and can be cultivated in cold climates like the US and Canada.

Tires used to be made from natural rubber, which came from the Brazilian rubber tree. Even Thomas Edison in the 1930 sought other plants to make natural rubber and found that the Canadian weed called the goldenrod was a good candidate. Edison, with Henry Ford and Harvey Firestone, tried to produce high quality natural rubber from it. But, that work was abandoned once chemists found how to make synthetic rubber from oil. Now, modern scientists are picking up where Edison left off.

Lettuce produces a flowering stem. Inside this stem is a milky substance that contains key ingredients to make natural rubber.

“We found it [lettuce] produces very high quality natural rubber but of a very low quantity,” Ro said. He continued, “the quality is almost the same as that from the Brazilian rubber tree.” This group is also exploring other plants to make natural rubber.

The work is still in the early stages, so it will be some time — five to ten years — before you see a tire with the words “Made from Lettuce, “ on the side. However, what needs no dressing is how impactful lettuce will be.

 

Next Generation Science Standards: NGSS LS2.A

The color of a leaf is a dance as one molecule exits and others make their way to center stage.

A leaf might seem very simple, but inside it is a chemical factory. Inside the leaf is chlorophyll, a green molecule, which trees use to turn sunlight into energy to grow.

Leaves act just like a factory. In it, one thing goes in and another thing comes out. Leaves take in light from the sun, carbon dioxide from the air, and water from the soil and change them to make sugars and starches. What goes in is sunlight, water, and carbon dioxide; what comes out is energy.

At the heart of this factory is that green chlorophyll molecule, which is working hard during the hot days. However, as the temperature drops at night and the amount of sunshine lessens, the trees know it is time to shut down for the winter. The chlorophyll in the leaves starts to break down and the green color starts to exit the leaf.

One secret about leaves is that hidden underneath the green molecule are other molecules that make the colors of yellow and orange. As the temperature drops, these colors are revealed. As for the reds and purple colors in leaves, they come from other molecules that the tree starts to make as the cold temperatures kick in.

Some years the colors in trees are bright. Other years they are dull. The best conditions for maximum color are cool days that are dry (but not too cold). If there is too much rain or wind — like during a storm — the fall foliage will not be ideal since leaves will fall off the trees. Also, an early frost makes the colors less bright. Interestingly, the colder it gets the redder the leaves will be, since the molecule that makes red prefers the cold.

So as you can see, fall foliage is a delicate dance of molecules. It only happens for a short time. So enjoy the fall colors and all that beautiful and vivid chemistry at work.

References:

Fall Colors in Upstate New York