Shellfish

Shellfish are aquatic invertebrates that people eat. They have exoskeletons, which are hard outer shells, and they live in both saltwater and freshwater. Shellfish include many different groups, such as molluscs, crustaceans, and echinoderms.

Molluscs used as food include clams, mussels, oysters, winkles, and scallops. Crustaceans that are eaten include shrimp, lobsters, crayfish, crabs, and barnacles. Echinoderms, like sea urchin, are also eaten in some places, especially their gonads, which are popular in many parts of the world.

Although some shellfish harvesting has been unsustainable, shellfish farming can help the environment. It can create reefs, filter water, and eat extra biomass, making the water healthier.

Terminology

The word "shellfish" can mean many different things. When someone says they are having shellfish for dinner, it might include clams, oysters, lobster, or shrimp. But in rules made by governments, "shellfish" might only mean certain kinds of molluscs like clams, mussels, and oysters, leaving out animals like shrimp and crabs.

Even though people usually think of shellfish as coming from the ocean, some kinds live in rivers and lakes. For example, people sometimes call crayfish and river mussels "shellfish" too. All shellfish do not have a backbone, which means they are not like fish that have bones inside them. Even though we sometimes call them "fish" in everyday talk, scientists use the word "finfish" to talk about real fish with bones, making shellfish different. The word "shellfish" can be used for one animal or many, and sometimes people say "shellfishes" to talk about different kinds.

Main article: Molluscs

Main articles: Crustaceans, Marine

Further information: Freshwater, Crayfish, Mussels, Vertebrae

Shellfish in various cuisines

People have been eating shellfish for hundreds of thousands of years, and today, shellfish dishes are enjoyed in almost every type of food around the world. They are a valuable source of protein, especially in areas near the ocean.

In Japanese cuisine, shellfish and their roe are used in many dishes. For example, sushi includes both raw and cooked shellfish, and sashimi is made from very fresh raw seafood sliced into thin pieces. In the United States, lobster is a special treat, especially in the Northeast. Families often cook lobsters for celebrations in events like a clam bake. Clams are also popular, used in dishes like clam chowder. In the Southeast and gulf states, shrimp is an important part of the local food, often fried or added to dishes like jambalaya in Louisiana. Crawfish are also a favorite there, usually boiled with spices. Oysters are enjoyed fresh at raw oyster bars in many coastal cities.

Some popular dishes using shellfish include:

• Ceviche
• Cioppino
• Clam chowder
• Curanto
• Fruits de mer
• Paella
• Sashimi and sushi
• Shrimp cocktail
• Lobster bisque
• She-crab soup

Religious dietary restrictions

Further information: Jewish dietary laws

Some religions have special rules about eating certain foods. For example, the Torah teaches that Jews should not eat shellfish, only fish that have fins and scales. This rule comes from the books of Leviticus and Deuteronomy. Because of this, many Jewish people do not eat shellfish. Some other groups, like Seventh-day Adventists, also follow these same food rules.

In Shia Islamic traditions, there are different opinions about whether shellfish is allowed. Most Sunni Muslims, except for a group called Hanafis, consider shellfish to be halal, which means it is permitted to eat.

Allergy

About 1% of people have a shellfish allergy, which usually appears more often in teenagers and adults rather than in young children.

Some people may have difficulty digesting shellfish, which can cause stomach problems like nausea or cramps, but this is not the same as an allergic reaction. These symptoms can also happen from eating food that is not handled safely.

Toxic content

Some shellfish, such as whelk, contain arsenic. This can be harmful if eaten in large amounts.

Shellfish caught in Alaska can sometimes cause a kind of poisoning called paralytic shellfish poisoning (PSP). This happens because of toxins from dinoflagellates, which are tiny plants in the water. These toxins can be very strong and make it hard to breathe. Warmer oceans are causing these tiny plants to grow more often, which can increase the chances of getting sick from shellfish.

Ecosystem services and reef-building

Shellfish like oysters and mussels can form reefs by grouping together. These reefs give homes to many sea creatures, help trap carbon to fight climate change, and protect shorelines from big waves and floods. When reefs are damaged, carbon can be released into the air, making bad weather more likely and taking away our natural protection. Some shellfish also clean the water by catching tiny particles and dirt, which helps keep the water clear and healthy for other sea life.