New research has begun to fully lift the lid on the global online trade in land crabs, leading scientists to call for closer monitoring and regulation to better understand any effects it may be having on native populations and global biodiversity.

The study highlights how the tropical aquatic aquarium trade, a multi-million dollar industry, has evolved to include sales of both hermit crabs (anomurans) and true crabs (brachyurans), growing significantly in popularity over the last two decades.

Even as long ago as 2003, these two groups of crabs made up the second most traded group of marine ornamental crustaceans, and they have only grown in popularity and access through the global expansion of the online animal trade. Sourced from wild populations or bred in tanks, they are also sold at specialist events and markets.

However, the global trade in these species is presently unregulated – despite eBay, one of the primary platforms, recently introducing rules banning the sale of live invertebrates – meaning the full extent to which brachyuran land crabs are traded is unknown.

Through the new research, experts at the University of Plymouth aimed to provide the first assessment of the extent and diversity of the international brachyuran land crab trade on a global level. They carried out a systematic survey of global e-commerce of brachyuran land crab species on English-language websites, focussing on those traded within the tropical freshwater and semi-aquatic aquarium industry and/or the exotic pet trade.

Over the space of four months, they analysed 574 advertisements by 15 different sellers based in the United Kingdom, United States and Europe who were between them making 25 different species available for purchase. The most common type of crabs to feature in the adverts were the Purple Vampire Crab (Geosesarma dennerle) and the Panther Crab (Pantherina panthera), but almost a third of the listings didn’t include a species name which makes them hard to identify.

The researchers also found that the crabs were being sold for anything from £5 to £120, and that most of the listings offered little or no advice on how best to care for the crabs and ensure their welfare. The research, published in Oryx – The International Journal of Conservation, was led by PhD researcher and BSc (Hons) Zoology graduate Miss Ella Whitaker and Dr Lucy Turner, Associate Professor in Marine Biology. They believe knowing the extent to which various species are traded will allow conservationists and policymakers to make informed decisions regarding legislation that monitors global imports and exports, and the wild catch of such species.