How do you know if a hermit crab is land or marine?

To determine if a hermit crab is land or marine, observe its habitat and physical characteristics. Land hermit crabs typically have a more robust, moist body and require a humid environment, while marine hermit crabs are found in saltwater and have gills for breathing underwater. Additionally, land hermit crabs often have a more pronounced shell for protection against terrestrial predators and desiccation, whereas marine species may have more streamlined shells suited for aquatic environments.