What Is a Group of Crabs Called? A Scuttle, a Clamor, a Cast?

A group of crabs is commonly called a cast or a swarm. RABI ELKESSAB / Shutterstock

Crabs scuttle along the ocean floor, dig in the sand and wave their claws during territorial standoffs. But what is a group of crabs called? These quirky, armored creatures actually have more than one collective noun.

In the world of marine life, crabs stand out for their variety. From hermit crabs and vampire crabs to Dungeness and horseshoe crabs, these animals thrive in oceans, estuaries and even on land. And yes, when they gather, there’s a name for that.

A Cast of Crabs

The most commonly accepted term for a group of crabs is "cast." This word likely refers to the way crabs move together during mass migrations, or when they gather to molt, breed, or feed.

The term is used across different species, including fiddler crabs, ghost crabs and more familiar types like Dungeness crabs.

During mating season or while searching for food, crabs may form large groups in shallow water or along beaches. These moments are when you’re most likely to see a cast in action.

Another Crab Term You Might Hear

While "cast" is the most recognized collective noun, you may also hear a group of crabs referred to as a swarm. It's not scientifically precise but is sometimes used informally when crabs move en masse across sand or in tidal pools.

Crabs are generally considered solitary creatures, but some species, like hermit crabs, will form temporary groups when resources or safety demand it. Mass molting or group nesting events are other times crabs band together.

Crabs in Nature and Captivity

In places like the Pacific Northwest or Maryland, crabs often gather in large groups during breeding season. Females may carry thousands of eggs, releasing them into the water where baby crabs hatch and drift as plankton.

Though crabs are vulnerable to predators like sharks, birds, raccoons and humans, their hard exoskeletons and burrowing behavior offer protection. Their claws help them feed on a range of items—including fish, shrimp, aquatic plants, and even smaller aquatic animals.

In aquariums or during seafood harvests, multiple crabs may be grouped together, but they’re often housed separately due to territorial tendencies.

Crustacean Cousins and Their Groups

Crabs belong to the same larger group of aquatic animals as lobsters, shrimp and barnacles. Other marine creatures have their own group names:

A school of fish
A pod of whales
A smack of jellyfish
A bale of turtles

Each term reflects movement, habitat, or behavior. A cast of crabs fits right in with this naming tradition.

Why Group Names Matter

Collective nouns help us describe not just numbers, but also behavior and character. Like a murder of crows or a parliament of owls, a cast of crabs captures something about animals’ nature—their sudden groupings, their synchronized movement, and the sense of drama they bring to the shoreline.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.