Chinese Horseshoe Crab

Tachypleus tridentatus

The Chinese horseshoe crab (Tachypleus tridentatus), also known as the tri-spine horseshoe crab, is a large chelicerate arthropod reaching up to 60 cm in body length including the telson (tail spine). It has a distinctive horseshoe-shaped carapace, six pairs of legs, book gills for breathing, and three telson spines that give it its scientific name. Found in Southeast and East Asia from Japan to Indonesia and Vietnam, it inhabits sandy and muddy coastal areas, estuaries, and shallow waters at depths of 0 to 30 meters. As a living fossil virtually unchanged for 450 million years, it represents one of the oldest surviving animal lineages on Earth. Its blue, copper-based blood contains LAL (Limulus Amebocyte Lysate), used to test for bacterial contamination in pharmaceuticals. Now endangered due to habitat loss and overharvesting, encountering one while diving is increasingly rare and ecologically significant.