1989. Based in Michigan, Keri Gardner has been writing scientific journal articles since 1998. All rights reserved. There are no known adverse effects of Macrocheira kaempferi on humans. The megalopa stage typically lasts an average of 30 days. The long legs of the Japanese Spider Crab enable them to move very quickly and to prey on their prey. flashcard set{{course.flashcardSetCoun > 1 ? The ADW Team gratefully acknowledges their support. The first pleopods of the male species of this crab are unusually twisted and its larvae appear ancient. May 02, 2011 Riebel, W. 2011. Okamoto, K. 2003. Japanese spider crabs most often inhabit the sandy and rocky bottom of the continental shelf and slope at an average depth of 150-300 meters. The chitosan prepared from crab tendon I: the characterization and the mechanical properties. The short, stiff eye stems on the Japanese Spider Crab are located at the front of the carapace and have two thin spines stuck between them. The female species of this crab has a wide abdomen and yet its legs continue to grow. Japanese spider crabs are usually discovered off the southern shorelines of the Japanese island of Honsh, from Tokyo Bay to Kagoshima Prefecture. (Encyclopaedia Britannica Online, 2011; Sakai, 1965; Ueda, et al., 1989), Many juveniles decorate their shells with sponges, kelp, or other objects to disguise themselves. Upon picking up the object with the crab’s slender chelipeds, the chelae is used to twist and tear off the organism, such as a worm tube or sponge, from the substrate that it currently resides on. Disclaimer: Mating behavior is rarely observed. [3] They like to inhabit vents and holes in the deeper parts of the ocean. [13], Female crabs carry the fertilized eggs attached to their abdominal appendages until they hatch into tiny planktonic larvae. Journal of Natural History, 25 (5): 1259-1279. Japanese spider crabs are the largest with leg spans that may reach 13 feet. The Japanese spider crabs natural habitat is on the bottom of the Pacific Ocean (some 300 – 400 metres deep) around the Japanese archipelago, where it feeds on dead animals and shellfish. They are found most often in the Sagami, Suruga, and Tosa bays, as well as off the coast of the Kii peninsula. Wicksten, M. 1992. This giant ornamental crab adorns the spider crab with its algae and has sponges to enhance its camouflage to hide from predators such as fish and octopus. (Wicksten, 1992). The Japanese Spider Crab is regularly seen at a depth of 300 m in Suruga Bay where the water is usually about 10 C. This type of crab tolerates between at least 6 and 16 C depending on the results of the public aquarium but is usually maintained at 10–13 C. The carapace of the Japanese Spider Crab is pear-shaped and narrow towards its head and light tones from dark orange. Although slow-moving, they use their claws against smaller predators. The Japanese Spider Crab can feed on carnivorous meat and carbs on the seabed. One study reported that nearly three quarters of these crabs are missing at least one limb, most often one of the first walking legs. The carapace of Macrocheira kaempferi is sub-circular and pear-shaped (pyriform), narrower towards the head. In the lab, at optimum growth conditions, only around 75% survive the first zoeal stage. The Japanese Spider Crab inhabits sandy and rocky bottoms in the Pacific Ocean around Japan. Japanese Spider Crab can grab and tear meat in powerful pincers. They can eat algae, plants, mollusks and small fish, catching and tearing up the meat in their powerful pincers. This number drops to around 33% for the second zoeal and megalopa stages. ""Crabzilla": The biggest crab ever seen in Britain...and it's still growing" The average size caught by fishermen is a leg span of 1.0–1.2 m (3 ft 3 in–3 ft 11 in). Bulletin of the Institute of Zoology, Academia Sinica, 29 (3): 207-212. Freeman, S. 2010. These giants go through three main larval stages along with a prezoeal stage in order to grow to their great size. [23] One of the primary methods of recovery of the species being utilized is restocking artificially cultured juvenile crabs in fisheries.