Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish. Shellfish include various species of molluscs (e.g. bivalve molluscs such as clams, oysters and mussels, and cephalopods such as octopus and squid), crustaceans (e.g. shrimp, crabs, and lobster), and echinoderms (e.g. sea cucumbers and sea urchins). Historically, marine mammals such as cetaceans (whales and dolphins) as well as seals have been eaten as food, though that happens to a lesser extent in modern times. Edible sea plants such as some seaweeds and microalgae are widely eaten as sea vegetables around the world, especially in Asia. Seafood is an important source of (animal) protein in many diets around the world, especially in coastal areas. Semi-vegetarians who consume seafood as the only source of meat are said to adhere to pescetarianism. The harvesting of wild seafood is usually known as fishing or hunting, while the cultivation and farming of seafood is known as aquaculture and fish farming (in the case of fish). Most of the seafood harvest is consumed by humans, but a significant proportion is used as fish food to farm other fish or rear farm animals. Some seafoods (i.e. kelp) are used as food for other plants (a fertilizer). In these ways, seafoods are used to produce further food for human consumption. Also, products such as fish oil and spirulina tablets are extracted from seafoods. Some seafood is fed to aquarium fish, or used to feed domestic pets such as cats. A small proportion is used in medicine, or is used industrially for nonfood purposes (e.g. leather). History The harvesting, processing, and consuming of seafoods are ancient practices with archaeological evidence dating back well into the Paleolithic. Findings in a sea cave at Pinnacle Point in South Africa indicate Homo sapiens (modern humans) harvested marine life as early as 165,000 years ago, while the Neanderthals, an extinct human species contemporary with early Homo sapiens, appear to have been eating seafood at sites along the Mediterranean coast beginning around the same time. Isotopic analysis of the skeletal remains of Tianyuan man, a 40,000-year-old anatomically modern human from eastern Asia, has shown that he regularly consumed freshwater fish. Archaeology features such as shell middens, discarded fish bones and cave paintings show that sea foods were important for survival and consumed in significant quantities. During this period, most people lived a hunter-gatherer lifestyle and were, of