# 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. - **Category:** [Animal](https://www.snappit.app/explore/categories/animal) - **Rarity:** Common - **Danger:** 1/5 · Very low - **Snaps:** 9 - **Habitat:** Found in rocky intertidal zones, typically hiding under loose stones or boulders along shallow coastal shores. ![Asian Shore Crab](https://inaturalist-open-data.s3.amazonaws.com/photos/31263774/medium.jpeg) Photo: Andra Waagmeester, CC0 · [iNaturalist](https://www.inaturalist.org/photos/31263774) ## 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. ## Taxonomy - **Kingdom:** Animalia - **Phylum:** Arthropoda - **Class:** Malacostraca - **Order:** Decapoda - **Family:** Varunidae - **Genus:** Hemigrapsus ## 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 - **Fleshy Pincer Vesicles:** 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. - **Broad Environmental Tolerance:** Capable of surviving wide fluctuations in temperature and salinity, allowing them to thrive in varied estuarine and intertidal environments. - **Prolific Reproduction:** 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](https://www.snappit.app/explore/european-green-crab) (*Carcinus maenas*) — Competes for food and habitat, often displacing this native crab in North American habitats. - **Prey:** [Blue Mussel](https://www.snappit.app/explore/blue-mussel) (*Mytilus edulis*) — Preys heavily on the juvenile and larval stages of this bivalve. - **Predator:** [Herring Gull](https://www.snappit.app/explore/herring-gull) (*Larus argentatus*) — Frequently hunted by coastal birds during low tide when exposed on rocky shores. - **Competitor:** [Blue Crab](https://www.snappit.app/explore/blue-crab) (*Callinectes sapidus*) — Faces competition and occasional predation from larger native crabs. ## Safety **Danger:** 1/5 · Very low No special safety notes yet. ## Frequently Asked Questions ### How to identify Asian Shore Crab? Look for fins, arms, tentacles, shells and body symmetry. Underwater light shifts colors, so structure and markings usually matter more than shade. Sea Creature Identifier: upload a photo and compare the visible details. ### 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 ## Where to spot - [Bellevue Avenue Historic District](https://www.snappit.app/guides/places/bellevue-avenue-historic-district) — Rhode Island, US · Historic District - [Camp Evans](https://www.snappit.app/guides/places/camp-evans) — New Jersey, US · Historic Site - [Fort Revere Park](https://www.snappit.app/guides/places/fort-revere-park) — US · State Park - [Harkness Memorial State Park](https://www.snappit.app/guides/places/harkness-memorial-state-park) — Connecticut, US · Botanical Garden - [Kennebunkport Historic District](https://www.snappit.app/guides/places/kennebunkport-historic-district) — Maine, US · Historic District - [Ocean Drive Historic District](https://www.snappit.app/guides/places/ocean-drive-historic-district) — US · Historic District [View all places to see Asian Shore Crab](https://www.snappit.app/guides/where-to-see/asian-shore-crab) ## More Animal - [Coquina](https://www.snappit.app/explore/coquina) (*Gymnoscelis coquina*) - [Crystal Jelly](https://www.snappit.app/explore/crystal-jelly) (*Aequorea forskalea Péron &*) - [Nautilus](https://www.snappit.app/explore/nautilus) (*Nautilus*) - [Sea Anemone](https://www.snappit.app/explore/sea-anemone) (*unclassified Amphianthus (in: sea anemones)*) --- Source: [Asian Shore Crab: Facts & Places to See — Snappit](https://www.snappit.app/explore/asian-shore-crab)