Alarm reaction and absence of alarm reaction to simulated predation on conspecifics in two temperate sea urchin species

Body fluids released by prey can signal the presence of a nearby predator. Numerous aquatic organisms show alarm responses to body fluids of conspecifics (reviewed by Chivers & Smith 1998, and by Ferrari et al. 2010). For nine sea urchin species, an alarm response to the smell of crushed conspecifics or the smell of extracts of conspecifics has been shown (Snyder & Snyder 1970, Mann et al. 1984, Parker & Shulman 1986, Campbell et al. 2001, Hagen et al. 2002, Vadas & Elner 2003). Two sea urchin species also responded to extracts from other species of the same genus (Parker & Shulman 1986). The sea urchins either moved to nearby shelter or moved away from the direction of the extract. We tested the two common, temperate eastern Atlantic sea urchins Arbacia lixula and Sphaerechinus granularis for the presence of such alarm reactions to simulated predation on conspecifics. (Introduction)Praxis XXI/BCC/16435/98