Striped Shore Crab

How to Distinguish from Similar Species: Both Hemigrapsus nudus and H. oregonensis have three teeth on the anterolateral margin of the carapace, plus do not have the transverse lines on the carapace.

Crevices, under rocks, in tidepools and mussel beds. Sometimes in clay burrows, especially in San Francisco Bay.

Depth Range: High and mid intertidal

This grapsid crab is different from all other grapsids because of the transverse lines on its carapace and the two teeth on the anterolateral margin of its carapace. Carapace to 4.8 cm wide in males, 4.1 cm in females.

Biology/Natural History: This crab can be very abundant in its range. It is the most semi-terrestrial of the shore crabs, living highest in the intertidal. Forages in and out of the water, active during the day. They spend at least half their time out of water but return periodically to pools to moisten their gills. They are osmoregulators, and can withstand hypo- and hyperosmotic conditions. It feeds on films of algae and diatoms, which it scrapes off the rocks with the tips of its chelae. May also eat small green algae Ulva and Enteromorpha, brown algae Fucus, and red Endocladia, Rhotoglossum, and Grateloupia. Occasionally eats dead animals or small intertidal invertebrates, and has especially been noted eating limpets. Predators include gulls, raccoons, anemones, and fish. Ovigerous females are found from March to September in central California; peak reproduction is in June and July. In central Japan this species can be parasitized by any of three sympatric sacculinid barnacles, Sacculina confragosa, S. imberbis, or S. yatsui.

Geographical Range: Charlston, Oregon to Isla de Santa Margarita, Baja California, + Gulf of California, Japan, Korea