Horseshoe crab live mainly in coastal shallow brackish waters with soft, sandy bottoms or mudflats.
The Chinese horseshoe crab Tachypleus tridentatus (TT) can tolerates colder temperature than the mangrove horseshoe crabs Carcinoscorpius rotundicauda (CR) and can be found in Southeast and East Asia including China, Indonesia, Japan, South Korea, Malaysia, the Philippines, Hong Kong, Taiwan and Vietnam.
CR can be found in South and Southeast Asia where the climate is tropical or subtropical, including India, Bangladesh, Indonesia, Malaysia, Singapore, Thailand, Cambodia, Vietnam, China and Hong Kong.