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Hemigrapsus oregonensis
Dorsal view of H. oregonensis
Ventral view of a male H. oregonensis
Common name(s): Yellow shore crab, green shore crab, hairy shore crab
Size:
Carapace width averages 15 mm, but is found with a width up to 35 mm.
Range:
H. oregonensis is found along the Pacific rim from California to Alaska.
Habitat:
This decapod is located in the upper intertidal regions of estuaries in high silt to muddy substratum, commonly found in sheltered areas underneath rocks and in eelgrass.
Color:
H. oregonensis has a yellow to light green carapace with pearl colored chela.
Misidentification:
This crustacean is often confused with H. nudus. Both are found in intertidal regions; H. nudus is found in more rocky outer shore regions. H. oregonensis can be identified by hairs on the pereopods, and lack of purple spots on the pincers.
H. nudusis most likely to be present in exposed rocky areas, whereas H. oregonensis is typical of quiet water and rocky habitats of estuaries. Both species of Hemigrapsus have a nearly rectangle carapace (Kozloff, 2000).
Life History:
Eggs brooded from females, in the Puget Sound region, begin as early as February and complete in April. An average of 7,650 eggs are produced per female.
Natural History:
H. oregonensis is considered a scavenger, primarily a vegetarian. Its food consists mainly of diatoms and algae scraped from rocks.
Predators:
Shorebirds. A parasitic isopod (Portunion conformis) in the area surrounding internal organs.
References:
Batie, Robert E. (1974). Population structure of the intertidal shore crab Hemigrapsus oregonensis (Brachyura, Grapsidae) in Yaquina Bay, a central Oregon coast estuary. Oregon State University, Ph.D., 1974, Marine Sciences. Ann Arbor, MI.
Kozloff, Eugene. Seashore Life of the Northern Pacific Coast. University of Washington Press: Seattle and London.
Sept, Duane, J. (2004). The Beachcomber's Guide to Seashore Life in the Pacific Northwest. Harbour publishing: BC Canada.
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Last updated Thursday, August 24, 2006, by Lisa Ferrier
