Most sponges are simple filter feeders—they eat small plankton and bacteria that they ‘filter’ from the surrounding water which they pump through their bodies. But in 2012, scientists on a research voyage off the coast of northern California discovered a sponge that uses small hooks along its vertical branches to entrap and devour larger, more nutrient-dense prey, like small crustaceans. The sponge’s elegant structure, which it likely evolved to maximize the area available for snaring food, inspired scientists to name the carnivorous deep-sea predator the harp sponge (Chondrocladia lyra).
The harp sponge is not the first carnivorous sponge scientists have discovered in the deep sea, although carnivory remains an exception among sponges. The feeding strategy is more efficient for animals adapted to the food-poor deep-sea environment, where filter-feeding costs valuable energy.
There’s still a lot more to learn about harp sponges, but they seem to thrive in the extremely stable environment of the flat, muddy seafloor in a relatively narrow depth range. Activities like deep-sea mining could disrupt these remote environments as well as the species that live there—both the ones we know about and the ones we don’t.