1. (A) Mean swim speed (±s. d
(A) Mean swim speed (±s.d.) of the two porpoises, Eigil and Freja, and of Freja blindfolded (Freja bf) in no fish trials (grey bars) and fish trials (white bars). *Significant difference in swim speed between fish and no fish trials for Eigil (P<0.05). ***Significant difference in swim speed between Freja with and without eyecups (P<0.001).
(A) Mean swim speed (±s.d.) of the two porpoises, Eigil and Freja, and of Freja blindfolded (Freja bf) in no fish trials (grey bars) and fish trials (white bars). *Significant difference in swim speed between fish and no fish trials for Eigil (P<0.05). ***Significant difference in swim speed between Freja with and without eyecups (P<0.001). The speed of the same individuals in the orientation task described previously (Verfuß et al., 2005) is shown for comparison (hatched bars). (B) Swim speed of the porpoises Eigil and Freja in fish trials (black line) and no fish trials (grey line). The swim speed is given as the running mean averaged over 10 video frames (0.4 s). The circles and horizontal bars give the mean distance to the reference (±s.d.) of the porpoise at the time the splash occurred in fish (black) as well as in no fish trials (grey). Number of trials for Eigil/Freja/Freja bf are: no fish=5/5/4 and fish=5/5/5.
Ursula K. Verfuß et al. J Exp Biol 2009;212:
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