Sponges are generally filter feeders, living off of bacteria and single-celled organisms sieved from the surrounding water. But some are more aggressive about obtaining their food. Researchers have recently discovered four new species of carnivorous sponges living on the deep seafloor.

The undersea critters—found in an area spanning the Pacific Northwest to Baja California—look like bare twigs or small shrubs covered with tiny hairs. But the hairs consist of tightly packed bundles of microscopic hooks that trap small animals such as shrimp-like amphipods. Once an animal becomes trapped, it takes only a few hours for sponge cells to begin engulfing and digesting it. After several days, all that is left is an empty shell.

You can read the study, "Four new species of Cladorhizidae (Porifera, Demospongiae, Poecilosclerida) from the Northeast Pacific," in the journal Zootaxa.