A Crab Called John

A Brazilian Navy expedition reveals the yellow crab Johngarthia lagostoma, or “John,” a terrestrial species found only on four oceanic islands—three in Brazil and one under British control off Africa. Its main refuge is Trindade Island, 1,200 km from the Brazilian coast, reachable only after four days at sea. Protected by the Navy and closed to civilians, the island hosts a research station with minimal human impact, creating ideal conditions for the crabs.
On Trindade, Johns range from beaches—where they mate and prey on green sea turtle hatchlings—to mountain peaks up to 600 m, home to juveniles. Though research has advanced, much about their biology, ecology, and genetic connectivity remains unknown. Endangered for two decades in Brazil, the species’ conservation status across different islands is still uncertain, raising questions about where protection is most urgent.