The researchers studied tiny animals living in deep-sea sediment in the northeastern Pacific Ocean. They found 18 different groups of these animals, with Sarcomastigophora being the most common. Nematodes, Crustacea larvae, Ciliophora, and Harpacticoida were also important. The highest number of animals was found at a depth of 4960 meters, while the lowest was at 4969 meters. The animals were most abundant near the surface and decreased in number as depth increased.