Unlike the amphipods, marine and freshwater isopods are entirely benthic. Its diet consists of polychaete worms and crustaceans, such as isopods and amphipods. Fish-free refugiums host populations of copepods, amphipods, isopods, and other zooplankton. Other invertebrates include ostracods, isopods, conchostracans, and bivalves. As other fish, groupers harbour parasites, including digeneans, nematodes, cestodes, monogeneans, isopods, and copepods. As other fish, serranids harbour parasites, including nematodes, cestodes, digeneans, monogeneans, isopods, and copepods. A woodlouse (plural woodlice) is a crustacean from the monophyletic suborder Oniscidea within the isopods. Over 50 species of other arthropods have been described (spiders, centipedes, millipedes, and isopods). It also consumes cephalopods and crustaceans, including decapods and isopods. Other ectoparasites found on gills are leeches and, in seawater, larvae of gnathiid isopods. Other external parasites found on gills are leeches and, in seawater, larvae of gnathiid isopods. Epaulette sharks are almost all parasitized by the praniza (parasitic) larval stage of gnathiid isopods. The effect is seen in unicellular organisms, green plants, isopods, insects, birds, mice, and hamsters. In some terrestrial isopods, these resemble lungs. This is evident as populations of isopods, mites and tumblebug scarabs decline significantly.