A systematic survey of brachyuran land crabs in the online tropical aquarium trade

Globally the tropical aquatic aquarium trade is a multi-million-dollar industry. Although marine ornamental fish and invertebrates are the main focus, tropical freshwater ornamental species including invertebrates (classed by the sector as semi-aquatic, such as land crabs) are also traded. Land crabs include both brachyurans (true crabs) and anomurans (false crabs, including hermit crabs). These are sourced from wild populations and/or tank-bred for use as ornamental commodity species. This global trade is unregulated and the full extent of the brachyuran land crab trade is unknown. Land crabs are important ecosystem engineers, and collection for the tropical freshwater/semi-aquatic aquarium industry is believed to be detrimental to their wild populations. We undertook the first systematic survey of the e-commerce of brachyuran land crabs, allowing us to document which species are traded globally and to what extent within the tropical freshwater/semi-aquatic aquarium industry and/or the exotic pet trade. Focusing on English language websites, we identified 15 sellers, based in the UK, USA and continental Europe. Twenty-three species were available for purchase, sold under 61 vernacular names, with listings that could not be identified to species falling into three genera. In five cases, a single vernacular name was used to refer to multiple species within or across genera. We recommend that comprehensive monitoring of this trade should be established, to understand the effects of land crab collection on their populations and whether any of the traded species could become invasive.