Asian Shore Crab

hemigrapsus sanguineus

The Asian Shore Crab (Hemigrapsus sanguineus) is a highly adaptable and opportunistic crustacean native to the rocky coasts of the western Pacific Ocean. Recognized for its remarkable hardiness and rapid reproduction rates, this small crab has successfully established itself as a prolific invasive species along the Atlantic coasts of North America and parts of Europe. Armed with a voracious appetite and a broad tolerance for varying temperatures and salinities, it quickly dominates intertidal zones, often outcompeting native crabs. While it is a fascinating subject for marine biologists studying invasive ecology, its presence can significantly alter local coastal food webs by heavily preying on small invertebrates and young bivalves.

Habitat: Found in rocky intertidal zones, typically hiding under loose stones or boulders along shallow coastal shores.

Appearance

The Asian Shore Crab is a small crab with a distinctively square-shaped carapace that typically measures up to 4.5 centimeters across. Its shell color is highly variable, ranging from mottled greenish-brown to dark purple or reddish-orange, which allows it to blend into rocky backgrounds. A key identifying feature is the presence of exactly three teeth, or spines, on each side of the carapace just behind the eyes. Its legs are unmistakably banded with alternating light and dark stripes. Additionally, adult males possess a distinctive, bulbous fleshy vesicle at the base of the movable finger on their pincers.

KingdomAnimaliaPhylumArthropodaClassMalacostracaOrderDecapodaFamilyVarunidaeGenusHemigrapsus

Asian Shore Crab

Interesting facts

Because a single female can produce up to 3 or 4 clutches of eggs each year, their populations can explode from just a few individuals to millions in a short span.

In their invasive range on the US East Coast, their densities can reach staggering numbers, sometimes exceeding 100 crabs per square meter of rocky shoreline.

Their distinctively banded legs make them easy to identify, earning them the nickname 'banded shore crab' in some coastal regions.

To escape predators, the Asian Shore Crab can self-amputate its own legs or claws, a process called autotomy, and regenerate them over subsequent molts.

Special abilities

Adult males have unique blister-like fleshy bulbs at the base of their claws, which are thought to play a role in mating displays or sensory functions.

Capable of surviving wide fluctuations in temperature and salinity, allowing them to thrive in varied estuarine and intertidal environments.

Females can produce multiple clutches of up to 50,000 eggs per breeding season, enabling explosive population growth in newly invaded territories.

Measurements & details

Length: 1-5 cm
Weight: 0.005-0.04 kg
Lifespan: 2-3 years
Clutch Size: 15000-50000
Incubation: 14-28 days

Diet & Feeding

An opportunistic feeder, the Asian Shore Crab consumes a wide variety of plant and animal matter, easily adapting its diet to whatever is most abundant in its habitat.

Age differences: Larvae are planktonic and filter-feed on microscopic plankton, while adults are benthic foragers eating larger algae and macroinvertebrates.

Primary Foods

Macroalgae
Juvenile bivalves
Amphipods
Polychaete worms
Small crustaceans

Foraging Method

Foraging

Ecological connections

competitor

European Green Crab

Carcinus maenas

Competes for food and habitat, often displacing this native crab in North American habitats.

prey

Blue Mussel

Mytilus edulis

Preys heavily on the juvenile and larval stages of this bivalve.

predator

Herring Gull

Larus argentatus

Frequently hunted by coastal birds during low tide when exposed on rocky shores.

competitor

Blue Crab

Callinectes sapidus

Faces competition and occasional predation from larger native crabs.

Traits

No trait badges are assigned for this object yet.

Also known as

No aliases listed yet.

Collections

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Safety

Danger

1/5 · Very low

No special safety notes yet.

Frequently Asked Questions

How to identify Asian Shore Crab?

The easiest way to identify Asian Shore Crab is to use the Snappit nature identifier app.

How long is Asian Shore Crab?

1-5 cm

How much does Asian Shore Crab weigh?

0.005-0.04 kg

How long does Asian Shore Crab live?

2-3 years

What does Asian Shore Crab eat?

An opportunistic feeder, the Asian Shore Crab consumes a wide variety of plant and animal matter, easily adapting its diet to whatever is most abundant in its habitat.

Where is Asian Shore Crab usually found?

Found in rocky intertidal zones, typically hiding under loose stones or boulders along shallow coastal shores.

How does Asian Shore Crab hunt?

Foraging

How many eggs does Asian Shore Crab lay?

15000-50000