Grunion shrimp. An isopod, two species of flies, sandworms, and a beetle have been found preying on the eggs. Some shorebirds such as egrets and herons prey on grunion when the fish are on shore during spawning. Seagulls, sea lions, and larger fish such as sand sharks have also been observed feeding on grunion during a grunion run. The reduction of spawning habitat due to beach erosion, harbor construction, and pollution is believed to be the most critical problem facing the grunion species. Despite local concentrations, the grunion is not an abundant species. While the population size is not known, all
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