An interesting case is the turtle PA05-4 that remained at the edge of the Loop Current for several months showing a highly sinuous apparent path and a low corresponding velocity but a straight motor path and high swimming velocity.
Secondly, due to the impact that ocean currents may have on an animals' movements [37] [39] we estimated the surface currents experienced by each individual in order to distinguish the animal's apparent path (including a current drift component) from its own swimming motion (hereafter referred as motor path).
(2) Yet, in similar fast-current oceanic TRAs such as the Loop Current, turtle PA05-4 showed a high straightness index for its motor path, a high swimming velocity opposite to the main current resulting in a slow apparent velocity and a low straightness index for the apparent path.
The passage from an oceanic transit area to a neritic TRA (FG05-5, SU05-1, PA05-4, PA05-5, UR05-1, UR06-3, UR06-3) wassociatedted with a decrease in swimming velocity (p<0.05 in all cases, except SU05-1, Table S1, Fig. 5), in the mean straightness index for the motor path and in dive depth (p<0.05 in all cases, except SU05-1, Table S1, Fig. 5).
The passage from a neritic transit area to a neritic TRA (FG05-5, PA05-5, UR06-2, UR06-3) was associated with a decrease in swimming velocity (Kruskal-Wallis followed by a post-hoc Bonferroni test, p<0.05 in all cases, Table S1, Fig. 5) and in the mean straightness index for the motor path while dive parameters remained similar except for UR06-2 and UR06-3 for which dive depth decreased.
Conversely, it was clear that motor nerve paths were more meandering in morphants and that the axons in these nerves were less compactly bundled than in control embryos.
For example, the responsible gene in Duane Retraction Syndrome (CHN1) is involved in ocular motor axon path finding of the sixth nerve.
Even if regeneration occurs it is unlikely to be complete, since most nerves are mixed motor and sensory paths and there is no control ensuring that regenerating fibres take the correct path.
First, when taking into account the influence of surface currents on the horizontal behaviour of the animals, it appears that, in general, turtles slowed down their swimming velocity as they reached TRAs and exhibited highly sinuous motor and apparent paths.
Within neritic TRAs, the mean swimming and apparent velocities were typically low (<45 cm.s−1, i.e. 39 km.day−1, Table S1, Fig. 5) with a lower straightness index along the motor and apparent paths than before reaching the TRA (mean D/L typically <0.8).
