Sponges are animals that eat tiny food particles as they pump water through their bodies. They are very common on Caribbean coral reefs, and come in all shapes, sizes and colors. Previous research concluded that sponge growth is most limited by food particle availability. But sponges are also used as food by angelfishes that nibble on them, decreasing their growth. Which is more important, food or predation? We tested both possibilities by putting sponge pieces inside and outside of protective cages in shallow water, and
in deep water where there are more food particles. After a year, sponges in cages grew a lot more because they were protected from angelfishes, but sponges did not grow more in deep water. Therefore, sponges are more affected by predation than food. Removal of angelfishes by fishing may result in sponges overgrowing and killing the corals that build coral reefs.