Fish posture

Jawless fish (450xl06 years) As for (2) with olfactory system and a cerebellum for maintaining posture while viewing. Very small cortex and telencephalox... 

The responses of the amphipod Gammarus minus to the odor of injured con-specifics resulted in an increase in the time until first attack by a fish predator (Wisenden et al. 1999). This delay should enhance the chances of prey to escape. The induction of a morphological change, spine development, in Daphnia by detection of predator odor results in increased chance of escape once attacked (Havel and Dodson 1984). The brachyuran crab //. rotundifrons responds to cues indicating increased predation risk by assuming an immobile, appendage-extended posture (Fig. 18.1). This posture mechanically inhibits predation by fish (Hazlett and McLay 2000) and exposure to the odor of crushed conspecifics increases the duration of this defensive posture. 

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