The Sierra Leone crab is very unusual in the world of crabs. This crab is extremely colorful, with purple claws and a bright body. It doesn’t spend very much time anywhere near the water. Instead, it lives in rock crevices or climbs trees to live in burrows. Some live in marshes or on the forest floor.

The expedition was supported by Re:wild, an organization launched in 2022 by a group of conservation scientists and Leonardo DiCaprio, a longtime supporter of environmental and conservation issues. Re:wild’s mission is to protect and restore the biodiversity of life on Earth.

The Sierra Leone crab (Afrithelphusa leonensis) was the eighth species on Re:wild’s 25 Most Wanted Lost Species list to be rediscovered.

“Most freshwater crabs in Africa live in rivers, streams, and lakes, and only a few species live in more obscure habitats away from water because they can breathe air as well as water, just like land crabs. These freshwater crabs, however, are few and far between,” Neil Cumberlidge, a researcher and biology professor at Northern Michigan University who worked with Mvogo Ndongo on the expedition, says Treehugger. Cumberlidge could not go to Sierra Leone because of the pandemic, so he had to consult via email.

“Only a few species are known, but those that do not disappoint because they are extremely colorful compared to their river living cousins, and climb trees, live in rock crevices, marshes, or in burrows on the forest floor all well away from permanent water. Sierra Leone, Guinea, and Liberia and the only countries in Africa where these crabs occur, and there are only five species known, all rare,” he said in an interview with Treehugger.

These species are rare, and they are close to extinction. “What makes them vulnerable to extinction is their rarity,” Cumberlidge told Mongabay. “They are both narrow range endemic species, found in just a small area and nowhere else in the whole world, which makes them both hard to find and vulnerable to threats that could wipe them out completely,” quotes mongabay.com.

Discoveries like these are important, yet bittersweet, the researchers say.

“These discoveries are important because we were thinking that both of these species might actually be extinct, because they had not been seen for many years (centuries in one case),” Cumberlidge says in treehugger.com.

“It is bittersweet because the joy of discovering lost species is mixed with the realization that while not extinct, they are both critically endangered species on the edge of extinction, and that urgent conservation interventions will be required to protect these species in the long term.”

“The new data generated by the expedition, such as more detailed information on habitat, ecology, population status, and threats, will allow us to reassess the Red List status of each of these species (this will likely be Critically Endangered, i.e., close to extinction),” says Cumberlidge.

“The next step is to devise a Species Action Plan detailing exactly how this will be done, and then implement protective measures in the field together with Sierra Leone conservationists.”