Crustaceans vs. Molluscs: Key Differences Explained
Crustaceans are jointed-shelled arthropods—think crabs, shrimp, lobsters. Molluscs are soft-bodied invertebrates wearing shells they sometimes make, like clams, snails, octopuses. Two kingdoms, two blueprints.
At the seafood counter we lump them together as “shellfish,” so menus, allergies, and fishing laws blur the line; your brain files both under “things that crack open for dinner,” not under biology.
Key Differences
Crustaceans sport exoskeletons, jointed legs, and segmented bodies; they moult to grow. Molluscs keep a muscular foot, unsegmented bodies, and often an internal or external shell they can abandon.
Which One Should You Choose?
Craving texture? Pick crustaceans—sweet, firm meat. Want versatility or pearls? Go mollusc—oysters, scallops, or squid adapt to raw, grilled, or sushi. Dietary restrictions: crustacean allergies rarely cross-react with molluscs.
Examples and Daily Life
Crab legs crack at a boil; mussels steam open in white wine. Aquarium hobbyists stock cleaner shrimp (crustacean) alongside nerite snails (mollusc), each solving algae problems differently.
Can vegetarians eat either?
No; both are animals, so neither fits vegetarian or vegan diets.
Which group includes octopuses?
Octopuses are molluscs, specifically cephalopods, alongside squid and cuttlefish.
Are barnacles crustaceans or molluscs?
Barnacles are crustaceans—tiny shrimp glued upside-down in calcite condos.