Crangonidae Haworth, 1825

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 106-107

Family Crangonidae Haworth, 1825

Sand shrimps, family Crangonidae , have subchelate first pereopods: the finger of the chela closes obliquely or horizontally across the distal end of the propodus, like the blade of a pocketknife. The rostrum usually is small and without teeth or absent except in Paracrangon echinata . The second pereopod, if present, is slender and equal on both sides, with an unsegmented carpus. The body is depressed or squat. Often, ovigerous females have a broader body than males. In species of Crangon , teeth may be present on the ventral midline of the abdominal somites. The endopod of the pleopods is short, especially on pleopods 2–5.

The nomenclature of the crangonids has undergone revision in recent years, and specialists still disagree over generic and subgeneric classification ( Zarenkov 1965, Christofferson 1988b). Schmitt (1921) used the generic name Crago for many species, and applied the name Crangon to species of snapping shrimp, now called Alpheus . The sand shrimps officially were named Crangon by a ruling of the International Commission on Zoological Nomenclature (1955–56). Revisions by Zarenkov (1965), Kuris & Carlton (1977) and Christofferson (1988b) changed additional designations.

The North Pacific is rich in crangonid shrimp. Species of Mesocrangon and Lissocrangon are confined to the North Pacific. Species of Argis , Crangon , Metacrangon and Neocrangon are more common in the North Pacific than anywhere else. Except for Pontophilus gracilis occidentalis , a subspecies of a cosmopolitan species, crangonids of the northeastern Pacific belong to genera that occur for the most part in the Pacific, Arctic or North Atlantic.

Species of Crangon , Mesocrangon , Lissocrangon , and Neocrangon are mostly benthic and able to dig into sand. Many remain hidden except for the eye, antennae and a respiratory channel. Most are dull-colored or camouflaged by chromatophores. They feed on smaller invertebrates. A parasitic isopod, Argeia pugettensis Dana, 1853 forms a bulge in the carapace next to the branchial chamber. Many demersal fishes, crabs, and harbor seals eat sand shrimps.

In using the key, best results will be obtained with fresh specimens. Diagnostic color marks usually fade in alcohol. In older preserved specimens, dorsal faint carinae and ventral sulci often are difficult to see. Pubescence is rubbed off in trawled material. The diagnoses for the most part follow Butler (1980).