High predation by the corallivore gastropod Jenneria pustulata was observed in July 2011 in a high-latitude reef at Bahía de Los Ángeles in the northern Gulf of California. Porites panamensis corals were infested by 15 to 40 sea snails per colony (22 ± 7.25 ind 0.1 m–2 of Porites surface). Coral colonies were 20–30 cm tall and the average size of the sea snails were 1.7 cm (SD ± 0.238, N = 152). These data indicate a change in the daily pattern of movement and feeding of the gastropod in this reef. Despite high density of J. pustulata on the reef, no soft corals were observed as damaged by the sea snail.