Mexican Jumping Beans Are Sensitive to the Color of Light – EarthSky

Ever watch a Mexican jumping bean wiggle and twitch across your hand? These tiny marvels of nature are more than just a quirky novelty. A new study published in the journal *Plants* reveals a surprising facet of their behavior – they’re sensitive to the color of light. And it turns out, they prefer the blue kind.

For those unfamiliar, these seemingly animate beans aren’t beans at all. Instead, they’re the seedpods of a specific shrub (S. sallaei), home to the larvae of a tiny moth (Cydia desquianella). The larva lives inside the seedpod, using silk to create its cozy cocoon.

It’s this wriggling larva, seeking the warmth of the sun, that causes the bean to jump. But as the new study by researchers at the University of Vienna revealed, the light doesn’t just influence the jumping action, it can actually control the larva’s direction. To discover this, researchers put groups of beans in specialized chambers, illuminating them with red, blue, and green lights, and observed the beans’ movements.

What did they find? Beans exposed to blue light exhibited a strong directional preference. This suggests that the larvae actively seek out the blue end of the light spectrum, similar to how plants favor certain light wavelengths for photosynthesis. It’s a fascinating observation, adding yet another layer to the mystery of these fascinating little “jumpers.”

While the precise reason behind this preference remains unknown, the scientists suggest it could be linked to the larva’s sensory capabilities and their natural habitat. These beans typically grow under the bright, open conditions of desert regions, where blue wavelengths of sunlight are abundant.

The study provides further evidence of the surprising ways nature can surprise us. From the sensitive movements of tiny moth larvae inside a seemingly inanimate bean to the intricate mechanisms driving plant growth, the world teems with mysteries waiting to be unraveled. It’s a constant reminder of the awe-inspiring power and sophistication of even the simplest forms of life.

So next time you hold a Mexican jumping bean, think about the remarkable, light-loving larva that makes it twitch. And as you watch its wiggles, consider the complex interactions between living organisms and their environment, shaping their behavior in fascinating ways.