The horseshoe crabs or "King crabs” are regarded as one of the most primitive animals existing in today's world, dating back to the period of 300 millions years. Of only the four extant species, two are known from the eastern cost of the Indian region and because of their unique morphological similarities with the fossil, Mesolimulus walchi they are called "living fossils". They play an important ecological role in the food web. A decline in its population will exert serious impact on other species. The biomedical industry produces a valuable substance known as ameboecyte lysate from the blood of horseshoe crabs. This substance is used to test a variety of biomedical products, vaccines and many other live saving drugs for the presence of endotoxins or any bacterial contamination. The present study is aimed at providing a foundation of vital information on its occurrence, habitat requirements, foods & feeding behavior, population dynamics with breeding activity and also neuro-endocrine function, which may lead to formulate an effective conservation–cum-management strategy to preserve these threatened and endangered harmless creatures.