Grunion bluish-green backs and silvery sides and bellies. Their snouts are bluntly rounded and slippery. Silversides differ from true smelts of the family Osmeridae in that they lack the trout-like adipose fin. Young grunion grow rapidly and are about five inches long by the time they reach one year old and are ready to spawn. Adult fish normally range in size from with a maximum recorded size of (La Jolla, Ca., 05-11-05). Average body lengths for males and females are , respectively, at the end of one year; at the end of two years; and at the end of three years.
USS Grunion Maru". Her first torpedo ran low, but despite its magnetic pistol it failed to detonate. Two more bounced harmlessly off the "Kano Maru" without exploding. However, the remaining torpedo missed its target and circled back, striking the periscope supports on the submerged submarine without exploding. The damage the torpedo inflicted, combined with a jammed rear dive plane, triggered a sequence of events that caused the loss of depth control. The "Grunion" lunged below her maximum operational depth, and at about 1000 feet would have imploded. What remained of the ship struck the seabed, breaking off about 50 feet of her