Grapsidae

Grapsidae is a family of true crabs, commonly known as shoulder crabs or clawless crabs, though these common names are not exclusive to this group. They are found in tropical and subtropical oceans worldwide, inhabiting coastal areas, rocky shores, and mangrove swamps. These crabs are characterized by their flattened, almost square carapace and their strong, often brightly colored claws. Many species are terrestrial or semi-terrestrial, spending a significant amount of time out of the water. They are typically omnivorous, feeding on algae, detritus, and small invertebrates.

Grapsid crabs play an important role in their ecosystems, acting as scavengers and contributing to nutrient cycling. Their behavior can vary greatly depending on the species and their specific habitat. Some are solitary, while others form aggregations. Reproduction usually involves external fertilization, with females carrying eggs attached to their pleopods. The larval stages are planktonic before settling to the bottom and developing into juvenile crabs. Despite their often-conspicuous appearance and abundance in coastal zones, many species of Grapsidae are not widely known to the general public due to their preference for less accessible intertidal and supratidal habitats. Their ecological significance and diversity make them an interesting subject for marine biologists and conservationists.