Suction feeding by predators limits direct release of alarm cues in fishes

Chemical alarm cues alert aquatic prey to the presence of an actively foraging predator. There is a large literature based upon responses to alarm cues derived from skin extract, because it is anticipated that prey skin is damaged when prey are attacked by a predator. However, many predators feed by suction feeding whereby prey are quickly drawn into the buccal cavity and swallowed whole with little, if any, direct contact between the teeth of the predator and the prey. Here, we test if predation by suction feeding releases chemical information in sufficient quantity to elicit an antipredator response in conspecific prey. In tests of individual zebrafish Danio rerio, we found that odor of crushed zebrafish produced a clear antipredator behavioral response, but water collected immediately adjacent to staged predation events between a largemouth bass Micropterus salmoides (122-145 mm TL) and adult zebrafish (39 mm TL) did not elicit alarm behavior, and did not differ from behavioral respo...