What would sessile organisms do with information provided by the light from “their meals?” Just because spicules on a sea sponge transmit photons doesn’t mean that that’s their function.

David Contey
Boulder, Colo

Each Euplectella sponge houses a pair of bioluminescent shrimp. The researchers speculate that the spicules transmit the shrimps’ light into the sponge’s surroundings. The glow attracts organisms that the shrimp eat. In turn, the sponge feeds on waste products of the shrimp .–P. Weiss