The waters around Japan In to the Pacific side of the Japanese islands,Japan
Japanese spider crab (Macrocheira kaempferi), the largest crab alive, found on the bottom of the Pacific Ocean. Portly spider crab (Libinia emarginata), a species of crab found in estuarine habitats on the east coast of North America. Hyas, a genus of spider crabs, including the great spider crab (Hyas araneus), found in the Atlantic and the North Sea. Maja squinado, sometimes called the European spider crab. No, spider crabs are not spiders (terrestrial, and of the arachnid  class) but are crustaceans (Japanese spider crabs are strictly  aquatic). They are, however, the largest … species of crab reaching  about 3.8m (12 ft) across. 1 person found this useful. The Japanese spider crab (高脚蟹, takaashigani, lit. tall-footed crab) , Macrocheira kaempferi, is a species of marine crab that lives in the waters around Japan. It has the largest leg span of any arthropod. It is the subject of small-scale fishery which has led to some conservation measures.  Crab spider as a name in common use [edit]. Rationalisation for the name crab spider is generally subjective and anecdotal. It is commonly said to refer to a fancied resemblance to crabs, or to the way such spiders hold their two front pairs of legs, or their ability to scuttle sideways or backwards. Among the Thomisidae crab spider refers most often to the familiar species of flower crab spiders, though not all members of the family are limited to ambush hunting in flowers. Crab Spider feeding on a Junonia atlites butterfly in a Zinnia elegans flower. overview. The Spider Decorator Crab, also known as Camposcia Decorator Crab or Decorator Crab, is a member of the Majidae family of spider and decorator crabs. It decorates its brown body with sponges, shells, rocks, and other items as a method of camouflage. It is nocturnal, hunting at night The Japanese spider crab Macrocheira kaempferi is mostly limited to the Pacific side of the Japanese islands, Konshu and Kyushu, usually at a latitude between 30 and 40 degrees North. They are found most often in the Sagami, Suruga, and Tosa bays, as well as off the coast of the Kii peninsula. The Japanese spider crab (高脚蟹, takaashigani, lit. tall-footed crab) , Macrocheira kaempferi, is a species of marine crab that lives in the waters around Japan. ((Libinia emarginata)). The Common Spider Crab is also known as the Portly Spider Crab or Atlantic Spider Crab. The shell or carapace of this crab is round and spiny, with nine small spines running down the center.  Also known as the portly spider crab or the nine-spined spider crab, the common spider crab is a long-legged and slow-moving crustacean that covers itself in algae and small debris as a defense against predators. Predators: Spider crabs belong to a grown known as decorator crabs: the crab's main defense against predation is ability to camouflage itself with various spines and tubercles, algae, debris and small invertebrates. Thomisidae is a family of spiders. The common name crab spider is often applied to species in this family, but is also applied loosely to many other species of spiders. Among the Thomisidae crab spider refers most often to the familiar species of flower crab spiders, though not all members of the family are limited to ambush hunting in flowers. Crab Spider feeding on a Junonia atlites butterfly in a Zinnia elegans flower. The giant spider crab is the largest known species of crab and may live up to 100 years. The Japanese name for this species is taka-ashi-gani literally translating to “tall legs crab.” Their armored exoskeletons help protect them from larger predators such as octopi, but giant spider crabs also use camouflage. 
http://www.answers.com/Q/Where_do_spider_crabs_live https://en.wikipedia.org/wiki/Japanese_spider_crab https://en.wikipedia.org/wiki/Crab_spider http://www.liveaquaria.com/product/prod_display.cfm?c=497+501+627&pcatid=627 http://eol.org/pages/2924326/details https://www.acaquarium.com/animals/common-spider-crab-2/ http://www.chesapeakebay.net/fieldguide/critter/common_spider_crab https://en.wikipedia.org/wiki/Crab_spider http://www.tnaqua.org/our-animals/invertebrates/giant-japanese-spider-crab
where do common spider crabs live