Snorkel teams hauled in an impressive catch of species, including this bath sponge, to the shores of Elliott Key during the Biscayne BioBlitz. The protein spongin, which forms the fibrous skeleton of most sponges, makes them soft to the touch relative to critters that use calcium carbonate or silica to construct their shells and skeletons.
Smithsonian reef biologist Nancy Knowlton pulled the dead sponge apart to reveal an entire community of tiny crabs, worms, and other species hidden within its pores. When the bath sponge was overexploited in the 1920s, she explained, ocean water became cloudier. That’s when people finally got wise to the sponge’s important role as a filter for bacteria.
Photos by Tim Greenleaf