The main predators of oyster larvae are filter feeders (i.e. comb jellies). Once an oyster becomes an “adult,” it's consumed by whelks, sea stars and people.
Young oysters are often eaten by fish, birds, blue crabs and sea otters. Filter-feeding invertebrates and polychaete larvae may also feed on them. Whenever the oyster reaches “adulthood,” it is then consumed mostly by snails, sea stars, blue crabs and people.
Sea stars are able to open oyster shells with pressure, then proceed to suck the oyster out and indulge its soft tissue.
While a blue crab eats almost anything in its path, a major predator for oysters (especially Atlantic oysters) are small snails, such as the Atlantic oyster drill. These snails actually live on oyster reefs. They use a type of acid to soften the oyster's shell, and a rasping tongue to drill holes into it. Oftentimes, these snails are inadvertently brought with the oysters when they're taken to the West coast.
Humans enjoy raw oysters as delicacies, such as oysters "on the half-shell." Their texture and taste of the sea is highly appealing. Cooked oysters, whether steamed, roasted, grilled or fried, are considered another high-end food. Oysters are also used in numerous recipes.