Hemigrapsus sanguineus, the Japanese shore crab or Asian shore crab, is a species of crab from East Asia. It has been introduced to several other regions, and is now an invasive species in North America and Europe. It was introduced to these regions by ships from Asia emptying their ballast tanks in coastal waters.
H. sanguineus has a squarish carapace, 2 inches (50 mm) in width, with three teeth along the forward sides; its pereiopods are marked with alternating light and dark bands. The males have a bulb-like structure at the base of the movable finger on their claws. Other distinguishing features include three spines on each side of the carapace. Adult sizes range from 35–42 mm width. These crabs are opportunistic omnivores that tend to favor other animals over algae. As crab density in an invaded area increases, so does the breadth of the species' diet, which suggests that competition alters selection of food. There currently is no mitigation against these crabs. A natural enemy of H. sanguineus is Sacculina polygenea, a parasite that attacks adult shore crabs and is specific to H. sanguineus.
Ecology and life cycle
H. sanguineus is an "opportunistic omnivore" that prefers to eat other animals, especially molluscs, when possible. It tolerates a wide range of salinities (euryhaline) and temperatures (eurythermic).
Females produce up to 50,000 eggs at a time, and can produce 3–4 broods per year. The eggs hatch into zoea larvae, which develop through four further zoea stages, and one megalopa stage, over the course of 16–25 days. The eggs typically hatch in late summer or fall, into larvae, and the juvenile crabs molt in five stages to become megalopae, which typically takes about a month. Once in this stage, the crabs settle and metamorphize into full-grown crabs. The larvae are planktonic, can be transported for long distances during their development into benthic adults.
Typically, the crabs live in areas with large rocks, such as between boulders on rocky shores. Hemigrapsus sanguineus inhabits many artificial structures such as on oyster reefs. H. sanguineus can tolerate other habitats, such as salt marshes.
The invasion of the habitat by the H. sanguineus has been characterized by rapid geographical expansion and widespread displacement of competing crab species. Although this species has been introduced to such a large habitat, H. sanguineus is eaten by native crustacean-eating fish in these areas. Since the crabs are so abundant, some types of native fish even prefer the invading crab. This may be due to the mouths of fish adapting to the size of H. sanguineus because they are the most abundant food source. On the other hand, native crabs also have adapted to eat H. sanguineus, possibly due to the availability of the food source or as an anti-predator strategy. There is a possibility that H. sanguineus could expand in numbers in some areas where it is invasive, potentially overwhelming the habitat and out-competing native crustaceans, such as the blue crab and lobster.
Because the crabs are opportunistic omnivores, they will eat anything they can get their mouths around. H. sanguineus prefers to consume animals, but during a period of starvation, these crabs tend not to show a food preference. Most of the animals consumed by H. sanguineus are small invertebrates, such as mussels, snails, and amphipods. The diet of these crabs is overall very broad.
The first record of this crab outside its native range was from Townsends Inlet, Cape May County, New Jersey (between Avalon and Sea Isle City) in 1988. The larvae are thought to have been transported in the ballast water of yachts and cargo ships. From the 1990s, it spread as an invasive species and become increasingly common, now ranging from eastern Maine (Great Wass Island) to North Carolina.
In 1999, H. sanguineus was reported for the first time from European waters, having been discovered at Le Havre (France) and the Oosterschelde estuary (in the Netherlands). It has since been found along a long stretch of the continental coast of the English Channel, from the Cotentin Peninsula to the Dover Strait. Its range has extended east and north along the North Sea coastline, including northwestern Germany and Western Jutland of Denmark. In the United Kingdom, it has been recorded from Guernsey and Jersey, and in Kent and south Wales. The species was first reported to be found in Sweden in 2012. In 2019, Swedish authorities reported that a private person collected more than 50 specimens of the crab in the vicinity of the island of Orust in the Skagerrak–Kattegat region. The specimens were very small, suggesting that the crab is now reproducing in Swedish waters. A couple of months later it was first reported from the Øresund, the narrow strait between the Danish Island of Zealand and the Swedish province of Scania. There is a single record of H. sanguineus in the Mediterranean Sea – a 2003 sighting in the northern Adriatic Sea – and a single specimen has been collected from the Romanian coast of the Black Sea, near Constanța, in 2008.
- Peter Davie (2012). "Hemigrapsus sanguineus (De Haan, 1835)". WoRMS. World Register of Marine Species. Retrieved November 24, 2011.
- "Hemigrapsus sanguineus, Asian shore crab" (PDF). Guide to Marine Invaders in the Gulf of Maine. Massachusetts Office of Coastal Zone Management. Retrieved July 29, 2012.
- "Asian Shore Crab (Hemigrapsus sanguineus)/species profile".
- Brousseau, Diane J.; Baglivo, Jenny A. (2005-01-01). "Laboratory investigations of food selection by the Asian shore crab, Hemigrapsus sanguineus: algal versus animal preference". Journal of Crustacean Biology. 25 (1): 130–134. doi:10.1651/c-2530.
- Takahashi, Tohru; Lützen, Jørgen (1998-04-01). "Asexual Reproduction as Part of the Life Cycle in Sacculina Polygenea (Cirripedia: Rhizocephala: Sacculinidae)". Journal of Crustacean Biology. Oxford University Press (OUP). 18 (2): 321–331. doi:10.2307/1549326. ISSN 0278-0372.
- "Hemigrapsus sanguineus (Asian shore crab)". www.cabi.org. Retrieved 2020-02-18.
- "Asian shore crab, Hemigrapsus sanguineus" (PDF). Climate Change and Thermal Sensitivity of Canadian Atlantic Commercial Marine Species. Climate Change Impacts and Adaptation Program, Natural Resources Canada. June 27, 2007. Project A515. Retrieved July 29, 2012.
- Micu, Dragoş; Niţă, Victor; Todorova, Valentina (2010). "First record of the Japanese shore crab Hemigrapsus sanguineus (de Haan, 1835) (Brachyura: Grapsoidea: Varunidae) from the Black Sea". Aquatic Invasions. 5 (Supplement 1): S1–S4. doi:10.3391/ai.2010.5.s1.001.
- "Asian Shore Crab". eattheinvaders.org. Retrieved 2020-02-18.
- Epifanio, Charles E. (March 2013). "Invasion biology of the Asian shore crab Hemigrapsus sanguineus: A review". Journal of Experimental Marine Biology and Ecology. 441: 33–49. doi:10.1016/j.jembe.2013.01.010.
- Heinonen, Kari B.; Auster, Peter J. (February 2012). "Prey selection in crustacean-eating fishes following the invasion of the Asian shore crab Hemigrapsus sanguineus in a marine temperate community". Journal of Experimental Marine Biology and Ecology. 413: 177–183. doi:10.1016/j.jembe.2011.12.011.
- Dragoş Micu; Victor Niţă; Valentina Todorova (2010). "First record of the Japanese shore crab Hemigrapsus sanguineus (de Haan, 1835) (Brachyura: Grapsoidea: Varunidae) from the Black Sea" (PDF). Aquatic Invasions. 5 (Supplement 1): S1–S4. doi:10.3391/ai.2010.5.S1.001.
- Jessica D. Sharon. "Japanese Shore Crab (Hemigrapsus sanguineus)". Illinois-Indiana Sea Grant College Program. Archived from the original on March 3, 2011. Retrieved August 26, 2007.
- Giménez, Luis; Exton, Michael; Spitzner, Franziska; Meth, Rebecca; Ecker, Ursula; Jungblut, Simon; Harzsch, Steffen; Saborowski, Reinhard; Torres, Gabriela (2020-07-14). "Exploring larval phenology as predictor for range expansion in an invasive species". Ecography. Wiley Publishing. 43 (10): 1423–1434. doi:10.1111/ecog.04725. ISSN 0906-7590. (Giménez ORCID 0000-0002-1472-2915, Torres ORCID 0000-0002-4064-0585)
- Stephenson, Elizabeth H.; Steneck, Robert S.; Seeley, Robin Hadlock (2009). "Possible temperature limits to range expansion of non-native Asian shore crabs in Maine". Journal of Experimental Marine Biology and Ecology. Elsevier BV. 375 (1–2): 21–31. doi:10.1016/j.jembe.2009.04.020. ISSN 0022-0981.
- McDermott, J. J. (August 1991). "A breeding population of the Western Pacific crab Hemigrapsus sanguineus (Crustacea: Decapoda: Grapsidae) established on the Atlantic coast of North America". The Biological Bulletin. 181 (1): 195–198. doi:10.2307/1542503. JSTOR 1542503. PMID 29303652.
- Associated Press (October 5, 2013). "Concern grows over Asian crab's spread in Maine". Maine Sun Journal. Retrieved October 6, 2013.
- Gérard Breton; Marco Faasse; Pierre Noël; Thierry Vincent (2002). "A new alien crab in Europe: Hemigrapsus sanguineus (Decapoda: Brachyura: Grapsidae)". Journal of Crustacean Biology. 22 (1): 184–189. doi:10.1651/0278-0372(2002)022[0184:ANACIE]2.0.CO;2. JSTOR 1549619.
- Jean-Claude Dauvin; Fabien Dufossé (2011). "Hemigrapsus sanguineus (De Haan, 1835) (Crustacea: Brachyura: Grapsoidea) a new invasive species in European waters: the case of the French English Channel coast (2008–2010)" (PDF). Aquatic Invasions. 6 (3): 329–338. doi:10.3391/ai.2011.6.3.09.
- Bernd Obert; Marc Herlyn; Michael Grotjahn (2007). "First records of two crabs from the North West Pacific Hemigrapsus sanguineus and H. takanoi at the coast of Lower Saxony, Germany" (PDF). Wadden Sea Newsletter. 2007: 21–22.
- GB Non-native Species Secretariat (September 2015). "Hemigrapsus sanguineus (Asian shore crab)". nonnativespecies.org. Archived from the original on 27 December 2018. Retrieved 6 October 2018.
- Seeley, Becky; Sewell, Jack; Clark, Paul F. (2015-01-01). "First GB records of the invasive Asian shore crab, Hemigrapsus sanguineus from Glamorgan, Wales and Kent, England". Marine Biodiversity Records. 8. doi:10.1017/S1755267215000809.
- Invasive crab found once more in Swedish waters, Radio Sweden, 2015-08-07
- Nytt fynd av blåskrabba nära Orust, Länsstyrelsen Västra Götaland, 2019-07-18, Swedish only
- Østebø, S.U.; S.M. Hansen (29 October 2019). "Sjældent krabbe-fund i Danmark vækker bekymring". TV2 News. Retrieved 30 October 2019.
- Species Profile – Asian shore crab (Hemigrapsus sanguineus), National Invasive Species Information Center, United States National Agricultural Library