Predator avoidance behaviour of Baltic littoral mysids<Emphasis Type="Italic"> Neomysis integer</Emphasis> and<Emphasis Type="Italic"> Praunus flexuosus</Emphasis>

The predator avoidance behaviours of two littoral mysid species, Neomysis integer (Leach) and Praunus flexuosus (Müller), were studied experimentally. In ingestion experiments, mysids responded to a combination of chemical and visual signals of perch (Perca fluviatilis), but not to each stimulus alone. In the presence of the combined visual and chemical predator signal the swimming activity and choice of habitat (open vs. artificial vegetation, the Charophyte Chara tomentosa or the brown alga Fucus vesiculosus) were also influenced. The two mysid species behaved differently when perceiving predation risk: N. integer reduced swimming activity, whereas P. flexuosus increased their use of the vegetation. The different antipredator strategies of the two mysid species reflect their different lifestyles, N. integer being a swarm-forming species and P. flexuosus living in association with aquatic macrophyte vegetation.Communicated by L. Hagerman, Helsingør