The horsehair crab, Erimacrus isenbeckii, (Japanese: ケガニ kegani), is a species of crab which is found mainly in the east Pacific, around the Hokkaido coast in the Sea of Okhotsk and the eastern Bering Sea and is frequently used in Japanese cuisine.[1][2] The catch for the species reached a peak in the 1950's at 27,000 tons, and has decreased since, reaching 2,000 tons in 2003.[3] They are commonly found on sandy benthic environments from shallow water to depths of up to 350 meters in water temperatures of around 15 degrees.[4][5][6]
Biology and Description
E. isenbeckii can reach over 1 kg in weight.[3]Erimacrus isenbeckii is known to feed three to four times in a ten to twelve hour time-span, and cannibalism is common for E. isenbeckii in the spring.[7][2] The carapace of E. isenbeckii can reach 100 to 120 mm in length in adults.[6] Like the two other species in the same family, the gonophores of females are exposed.[8]
Life Cycle
The embryonic development of the species can be divided into 9 stages, each defined by cleavage and formation of distinct appendages. To incubate the eggs after spawning, females attach them to their pleopods.[9] Based on many surveys conducted during the spawning and hatching seasons, the incubation period of the species is estimated to be over a year , with the embryonic growth rate mainly being controlled by the temperature of the water.[10] Young hatch between March to May, and remain as zooplankton until they reach the bottom of the sea by July.[11] The hatching process occurs during the spring phytoplankton bloom in the Sea of Okhotsk.[12][13] The zoea of this species can be mistaken for the two other species in the same Family, but E. isenbeckii zoea lack carapace spines and have shorter lateral spines on the fork of the telson.[8]