Alpheidae Rafinesque, 1815

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 58

Family Alpheidae Rafinesque, 1815

The snapping shrimps, family Alpheidae , are reminiscent of small lobsters. At least one of the first pereopods is heavily chelate. The carpus of the second pereopod is divided into articles. The eye may be exposed or covered by the front of the carapace. Most snapping shrimps hide in burrows, tubes or cracks by day and are active at night.

Most snapping shrimps are much more diverse in the tropics than in temperate regions. Wicksten & Hendrickx (2003) reported 76 species of this family in the Eastern Tropical Pacific , but only 15 species have been reported from San Diego northward. Species of Betaeus , the visored shrimps, range as far north as Alaska .

There have been few studies of the natural history of snapping shrimps in California. Species of Automate and Alpheopsis usually have been taken subtidally in box cores or grab samples, which suggests that they are burrowers. Species of Alpheus live under rocks, in cracks or holdfasts or among worm tubes. Alpheus clamator Lockington, 1877 ; A. bellimanus Lockington, 1877 ; and Synalpheus lockingtoni Coutiére, 1909 are abundant from lower intertidal areas to offshore kelp beds, shale reefs and rocky areas. Alpheus californiensis most often occurs in protected bays. Species of Betaeus live in pairs in tide pools or as associates of other invertebrates.

Species of Alpheus are noted for the loud snaps, clicks and pops produced when the enlarged tooth of the dactyl of the major chela strikes the palm. The sounds function in territorial defense, prey capture and distraction of predators ( Schein 1977; Versluis et al. 2000).

Many species of alpheids are sexually dimorphic, with males often having larger chelae. In species of Alpheus , the chelae of males often have better-developed ridges, rows of setae and teeth than do those of females. Males of Alpheopsis and Betaeus tend to have a gape between the fingers of the chela than do females.

Several specimens of an unidentified species of Salmoneus Holthuis, 1955 , have been found in Long Beach Harbor, California (D. Cadien, pers. comm.) Species of this genus have a large, flat rostrum and chelae with unusually inflated areas proximal to the fingers. Banner & Banner (1981: 52–54) gave a key to all known species of Salmoneus . Diagnoses of species of Alpheus given here follow Kim & Abele (1988); those of species of Betaeus, Hart (1964) .