What is strange about the way that this crab breathes?

This was a difficult one. The crab is a Ghost Crab, that lives on the beach at our home in St. Augustine. Ghost crabs breath with gills, which means that they need water to breath. In spite of that, Ghost crabs live high up in the beach dunes, far away from the ocean. Every night, the crabs run down to the water to get their gills wet. That water has to be enough to let them breath until the next night.