prey, while others may be encountered on the bottom unburied or actively swimming. Large sharks, including the great white shark (Carcharodon carcharias) and the broadnose sevengill shark (Notorynchus cepedianus), and the northern elephant seal (Mirounga angustirostris) are known to consume Pacific angelsharks. Known parasites of this species include the copepod Trebius latifurcatus, which infests the skin, the myxosporidian Chloromyxum levigatum, which infests the gall bladder, and the tapeworm Paraberrapex manifestus, which infests the spiral valve intestine. The leech Branchellion lobata may be attached around this shark's cloaca, inside the intestine, and even inside the uterus and on developing embryos. Feeding A sedentary ambush predator, the Pacific angelshark feeds mainly on bony fishes, including kelp bass, croakers, flatfishes, damselfishes, mackerels, and sardines. During the winter and early spring, spawning squid are abundant and become the primary source of food. In the southern Gulf of California, the most important prey species are, in descending order, the mackerel Decapterus macrosoma, the toadfish Porichthys analis, the lizardfish Synodus evermann, the soldierfish Myripristis leiognathus, and the shrimp Sicyonia penicillata. At Catalina Island, this species feeds mainly on the blacksmith (Chromis punctipinnis) and the queenfish (Seriphus politus). Adults and juveniles have similar diets. Individual sharks choose sites giving them the best ambush success. They prefer junctions of sandy and rocky substrates near reefs (used by many fishes for shelter) usually orienting themselves either toward or parallel to nearby vertical structures. They tend to face upslope, which may facilitate burying via falling sediment, bring more fish swimming downstream from the reef, or ease targeting by silhouetting prey against the sunlight. Once settled at a successful site, an angelshark may remain there for ten days, re-burying itself on or near the same spot after every strike. As the local prey eventually learn to avoid the stationary predator, the shark periodically shifts at night to a new site several kilometers away. One study off Santa Catalina Island found that over 13–25 hours, nine sharks together used only 1.5 km2 (0.6 mi2). A later, longer-term study found that the sharks' sporadic position changes covered as much as over three months, almost circling the island. Single individuals swam up to in a night. The Pacific angelshark is primarily a visual hunter; experiments in nature show that they strike at fish-shaped targets without any electrical, chemical, vibrational, or behavioral cues. At night, they are guided by the bioluminescence of planktonic dinoflagellates and