Spiny Spider Crab
Maja brachydactyla
Sighting evidence at Ponta da Piedade, Algarve
Spider crabs aggregate in their thousands under the limestone arches from April through June during their annual moulting migration, forming mounds of interlocked animals that create a surreal spectacle in the arch ceilings. The aggregation behaviour provides mutual protection during the vulnerable soft-shell phase immediately after moulting, when predation risk is highest. They are an ecologically important benthic omnivore that reprocesses organic material across the rocky substrate.
Evidence at this site
No confirmed records on file at this site
Spiny Spider Crab is listed as a curated species here based on historical reports.