Human uses of living things used; and as symbols or concepts through totemism and animism. More recently, anthropologists have also seen living things as participants in human social interactions. This article describes the roles played by living things in human culture, so defined. The human population exploits and depends on a large number of animal and plant species for food, mainly through agriculture, an essential component of human culture, but also by exploiting wild populations, notably of marine fish. Livestock animals are raised for meat across the world; they include (2011) around 1.4 billion cattle, 1.2 billion sheep and 1 billion domestic pigs. Plants provide
Round goby Nord-Ostsee (Kiel) Canal. As of 2010, the westernmost site of round goby occurrence in Europe was the Lower River Scheldt, the tidal zone in the river mouth, and Albert Canal, Belgium. In 2011, the round goby began invading the fresh waters of France: the species appeared in the Rhine River (on the border between France and Germany), and in the French part of the Moselle River. In total, 52 parasite species are registered in the round goby in the native area. Most abundant parasites of the Black-Sea round goby are metacercariae of trematodes of Heterophyidae family, such as "Cryptocotyle concavum",