Tropical marine ecosystems support enormous biodiversity resources which are vital for livelihoods of coastal and inland populations across the regions. These include endemic and endangered marine and estuarine animal species that may hold an option value for mankind. This is particularly true for horseshoe crab, an iconic ancient marine species from the dinosaur era. Horseshoe crabs sensitive response to contamination has made its blood valuable in bacteria detection. This brings us to the issues of conserving this species for its option and bequest values in commercialization. Malaysian marine water harbours three out of four extant horseshoe crab species in the world. Not only being harvested directly for food source and delicacy in this region, this species population is now dwindling following anthropogenic induced habitat fragmentation. Changes in horseshoe crabs’ habitat physical environment have led to reduced spawning areas for them. Similar to threat faced by turtle and other marine species, horseshoe crabs are also prone to incidental catches dua to trawlers or fisherman gears. The publication of this book will facilitate the vital part of conservation effort for this species which is providing a fundamental understanding on the biology and ecology. This will also provide a platform in creating awareness and educating larger public to help protect this species for our future generations.