#900 Why are blueberries blue and strawberries red?

Why are blueberries blue and strawberries red? Because of the animals the plants want to eat their fruit.

Flowers and fruit tend to be a certain color because they have either evolved to attract a certain kind of animal or to repel a certain kind of animal. A lot of flowers and animals as well use color as a method of warning.

It actually turns out that how blueberries are blue is just as interesting as why they are blue. If you have ever made a blueberry smoothie, you will have noticed that it is not blue. Any blueberry drink you make will come out a deep purple because the pigment that makes blueberries blue is not inside them. Blue is a very rare color in nature and only about 1% of animals and plants that appear blue are actually blue. This is because there are very few natural compounds that release blue light. You might think that is not true because there are blue butterflies, blue frogs, and, obviously, blueberries. However, not all of them are not actually blue. The blue poison dart frog is actually blue. It’s skin contains a rare pigment called pumiliotoxin that reflects blue light. Blue butterflies are not blue. They don’t have any blue pigments. What they have is a microscopic arrangement of cells on the surface of their wings that scatter the light, making them appear blue. A lot of blue animals have this property. You can tell if the animal is really blue or not by looking at it from a different angle. If the animal is blue, the color won’t change. If it isn’t really blue, but just reflected light, the color will change with the angle.

Blueberries fit into this refracted light category. Blueberries are a deep purple or red color, and I think purpleberry is a pretty cool name. They don’t have any blue pigment. They have is a dark red pigment called anthocyanin. Strawberries also have this pigment and it can make bright reds as well as darker reds. What blueberries do have is a waxy covering on the fruit that has nanostructures that scatter the light, making them look blue. You can test this for yourself by rubbing the waxy coating off the blueberry. It will lose its blue color and become a dark purple. This wax has a number of purposes. Its job is to keep the berry waterproof and to stop infections or parasites. It is also to make the berry blue.

So, why are blueberries “blue” and strawberries red? Fruits and flowers tend to be the color that attracts the most beneficial insects or animals to that fruit or flower. Or that warns away the most animals and insects. Flowers have three goals: to make energy through photosynthesis, to reproduce by pollination, and to spread their seeds as far and as wide as possible. Colors help with all of these things.

Green is the color the absorbs the best light for them to photosynthesize. There is as much energy as they can take without being damaged. Red wouldn’t have enough energy and blue would have too much energy. Green is perfect.

The bright colors of the flowers have evolved to attract their pollinators. We think of bees as being major pollinators, and they are, but wasps, spiders, and even birds also pollinate flowers. The color of the flower attracts the insect of the animal, they stick their head or body in the flower, and come out carried in pollen, which they then carry to another flower.

The color of the fruit has evolved so they can be seen and eaten. Fruit producing flowers spread their seeds by being eaten. The animal gets the energy from the fruit, and the seeds pass undigested through the animal until they are pooed out later on. The color of the fruit usually connects to the type of animal that eats it. Strawberries are eaten by some animals, but by a lot of birds. That is why they have lots of small seeds to ensure that the birds eat as many seeds as possible. Birds have good color vision and the red fruit helps it to stand out against the green background of the bush. The animals that eat it can all see reds and greens. Blueberries, on the other hand, may not appear very bright, but they have evolved to be eaten by animals that can’t see reds very easily. A lot of mammals can’t see reds, but they can see blues. Blueberries are also eaten by a lot of birds because they appear blue, but they also give off ultraviolet light, which birds can see. So, that is why blueberries appear blue and strawberries are red. And this is what I learned today.

Photo by Jessica Lewis 🦋 thepaintedsquare: https://www.pexels.com/photo/selective-focus-photography-of-bunch-of-blueberries-583837/

Sources

https://askabiologist.asu.edu/colors-animals-see

https://www.livescience.com/chemistry/why-are-blueberries-blue