Diogenidae Ortmann, 1892

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 174-175

Family Diogenidae Ortmann, 1892

The "even-clawed" hermit crabs are widely distributed, especially in tropical regions. Ayón-Parente & Hendrickx (2010), in a study of species richness in the eastern Pacific, called attention to the paucity of genera and species in the northern temperate provinces. At most, only seven species in three genera occurred in the Californian and Oregonian provinces while 55 species in 11 genera occurred in tropical provinces. In their analysis, Clibanarius digueti Bouvier, 1898 and Dardanus magdalensis Ayón-Parente & Hendrickx, 2009 ; neither of which has been recorded farther north than Magdalena Bay, Baja California, were included as northern temperate species.

In California and Oregon, diogenids are primarily subtidal, although Isocheles pilosus may be exposed at very low tide. Except for Paguristes parvus , the crabs often have setose second antennae. These antennae can be used to capture particles, which are swept off by the third maxillipeds and then eaten ( Wicksten 1979a, 1988b). The crabs also can graze and scavenge, feed on smaller invertebrates, or use the third maxillipeds to brush edible debris off the bottom.

Species of the Diogenidae include some of the largest hermit crabs of the area. The shells may contain small polychaetes or slipper shells ( Crepidula and Crepipatella spp. ) Bryozoans, algae, or barnacles often heavily encrust shells inhabited by epibenthic species. Although these hermit crabs often seen by divers, there have been few studies or observations on their natural history.

Schmitt (1921: 126, pl. 17, figs. 3, 4) described an additional species, Dardanus jordani , from San Francisco Bay , California. The species, based on a single specimen, has not been reported since then. The locality of the collection may have been error, or the specimen might have been of a species native to some other part of the world .