Grunion classified in the family Atherinopsidae along with other New World silversides including the jacksmelt and topsmelt. The California grunion, "L. tenuis", is found along the Pacific Coast from Point Conception, California, to Punta Abreojos, Baja California Sur. They are rarely found between San Francisco in the north and San Juanico Bay, Baja California Sur, in the south. The Gulf grunion, "L. sardina", is found along the coast of Baja California in the Gulf of California. Inhabiting the nearshore waters from the surf to a depth of , marking experiments indicate they are not migratory. They are small, slender fish with
USS Grunion the exact location indicated by the commander of the "Kano Maru". The sunken object had many characteristics typical of a submarine. In 2007, using a ROV, DSSI/Oceaneering returned to the site and took video recordings of the imploded remains of a submarine, which had markings in English, and propeller guards and limber holes identical to those of the "Grunion". The following year, the US Navy confirmed that the find was the "Grunion". Although it is not absolutely certain, the evidence strongly suggests that the "Grunion" was lost as a result of multiple torpedo failures during her encounter with the "Kano