How Sponges Use Light to ‘Think’

SciShow host Rose Bear Don’t Walk discussed how researchers are finding that certain sponges, such as the Venus Flower Basket, use light to think and transmit internal information.

Sponges might not look like particularly complex animals, but they’ve had billions of years to evolve their own special systems. And one of those systems might involve sending messages through their body in the form of light.

These sponges, known as glass sponges, have a lacy skeleton made up of silica fibers known as spicules which, like fiber optics, can conduct light. Other sponges have proteins that give off light when mixed with oxygen to create bioluminescence or cryptochromes that get activated by light to send chemical messages.

These molecules move through the body much more slowly than nerve signals. But like nerve signals, they can also trigger certain behaviors in cells. Like, they can make cells contract or kick their metabolism into gear, all in response to what’s going on in the sponge’s environment. In other words, a combination of bioluminescent cells, glass fibers, and cryptochromes could be acting like a unique kind of sensory system, not yet observed anywhere else in nature.