leucophryna, Synandwakia multitentaculat dohelice subquadrata, Ellobium chinense, Clithon retropic- tus) inhabit intertidal regions, such as tideland or brackish water zones. Excluding Perisesarma bidens and Uca lactea, 9 of these species bear high ecological value as endemic species to the coastal regions of Asia. However, their habitats are directly affected by human activity such as the reclamation of tideland, pollution, and coastal improvement, as they are located on the boundary between ocean and land. As such, they are in need of urgent protection.

Crabs, which are a representative marine species of Korea, belong to phylum Arthropoda, class Crus- tacea, order Decapoda. They have a thick shell, a pair of claws, and four pairs of legs, and are the most evolved arthropods inhabiting the sea and freshwa- ter. There are over 4,500 species of crabs across the globe and approximately 200 species inhabit Korea. Among these, about 60 species can be found in tidal ats, brackish water zones, or the foot of mountains by the seaside. The rest inhabit the subtidal zone and the deep sea. Upper and intermediate tidal ats (including brackish water and supratidal zones) are highly exposed to development processes by anthro- pocentric activities, and thus require management and conservation measures.