Shellfish can be collected from intertidal areas using a spade or rake and put through a sieve to extract the ones of marketable size.
Seafood can be found in coastal zones as well as rivers and lakes around the world. Seafood suitable for gathering by hand includes aquatic invertebrates such as molluscs, crustaceans, and echinoderms as well as aquatic plants. Some molluscs (shellfish) commonly gathered are oysters, clams, scallops and cockles. Some crustaceans commonly gathered are lobster, crayfish, and crabs. A common plant gathered is kelp. Echinoderms are not gathered as much as mollusks and crustaceans. In Asia, sea cucumber and sea urchins are gathered.
Very little, or no specialized equipment is required to gather many of these sea foods. We would expect to see evidence for shellfish consumption in prehistory, since the discarded shell can remain for long periods. In fact the earliest evidence for shellfish consumption dates back to a 300,000 year old site in France called Terra Amata. This is a hominid site as modern Homo sapiens did not appear until around 50,000 years ago. The importance of shellfish in prehistoric diet has been the source of much debate in archaeology. Sometimes they are referred to as a famine food and their nutritional value is played down at the expense of terrestrial or non-marine food sources.
Some shellfish are gathered by diving. Pearl diving is the practice of hunting for oysters by free-diving to depths of up to thirty metres. Abalone are also gathered by diving. Divers can also catch lobsters by hand.