Calappa calappa, also known as the smooth or red-spotted box crab, is a tropical marine species of crab with an Indo-Pacific distribution, and showing great variability in its patterning and colouration. First described as Cancer calappa by Linnaeus in 1758 from a specimen originating from Ambon Island, and later in 1781 as Cancer fornicatus by Fabricius, it was finally placed in the genus Calappa by Lancelot Alexander Borradaile in 1903. The name calappa is associated with kelapa, the Malay word for 'coconut'.