Ammodytes americanus, also known as American sand lance, American sand eel, and sand launce, is a small fish in the family Ammodytidae. First described by James Ellsworth De Kay in 1842, it is widespread in the western North Atlantic. Like all sand lances, it has a long, thin body with a pointed snout; mature fish typically range from 4to in length, though some may reach 7inches. Its back is greenish-brown, while its sides and abdomen are silvery. It has a long, low dorsal fin (described as "very delicate") which extends along most of its back, folding into a groove at the fin's base when not in use. Its anal fin is roughly the same height as the dorsal fin, and extends over the posterior third of the fish's body. Its pectoral fins are small, and its caudal fin is forked. Its mouth is large and toothless, with a lower jaw that extends well beyond the upper. It typically travels in large schools, spending most of its time relatively near the water surface. It feeds primarily on plankton, though it is known to take small clams and snails from the sea floor, presumably when plankton is scarce. Towards dusk, schools of A. americanus bury themselves in sand, typically from 1to below the sand's surface close to the water's edge; they avoid rocky areas. They do this to avoid being detected by night-hunting species such as bluefish and stripers.
Ammodytes americanus is an important prey item for many species of fish, whales and birds. Breeding roseate terns, a federally endangered species in the United States, feed their chicks almost exclusively on the species.