About Cycloxanthops novemdentatus (Lockington, 1877)
Cycloxanthops novemdentatus is typically brown or red in color, but it can also be purple. Individuals of this species often have dark or light markings on their shell, and these markings remain visible after molting, though the overall shell color may change over time. The species gets its common name from two sets of anterolateral teeth along the front edge of its carapace, with nine teeth in each set. The carapace can grow up to 3.75 inches wide. Immature individuals can be told apart from adults by the width of the third and sixth abdominal segments, the length of marginal abdominal hair, a sparse layer of hair on the swimmerets, and the presence of a lock mechanism in males. Once individuals reach approximately 6.5 mm in carapace width, sexual dimorphism becomes visible, caused by differences in the size and shape of abdominal segments. This species is the largest member of the family Xanthidae that occurs in California. In terms of distribution and habitat, Cycloxanthops novemdentatus lives in the eastern Pacific Ocean, ranging from Monterey, California to Baja California, and it is most abundant in the southernmost parts of coastal southern California. It inhabits rocky intertidal and subtidal habitats down to a depth of 240 m. Younger crabs are usually found in higher regions of the intertidal zone than adult crabs.
