Xanthidae

Xanthidae is a family of crabs, commonly known as rubble crabs, pebble crabs, or mud crabs. They belong to the superfamily Xanthoidea. This family is characterized by its broad, flattened carapace, typically with a granulose or rugose (wrinkled) surface. Xanthid crabs are found in a wide variety of marine habitats, including rocky intertidal zones, coral reefs, and muddy estuaries. They are generally small to medium in size and are often brightly colored.

Xanthid crabs are primarily carnivorous or omnivorous, feeding on small invertebrates, algae, and detritus. Their strong claws (chelipeds) are used to crush shells and other hard materials. Many species are ecologically important predators in their respective environments.

Systematically, the classification within Xanthidae has undergone revisions and remains a subject of ongoing research. Several genera have been moved between families based on molecular and morphological data.

Some species of Xanthidae are known to accumulate toxins, such as saxitoxins and tetrodotoxin, making them potentially poisonous to consume. Caution should be exercised when handling or considering eating any xanthid crab, especially in areas where toxic species are known to occur. Their toxicity often derives from their diet.