Predominance of clockwise swimming during rest in Southern Hemisphere dolphins.

Observations on eight bottlenose dolphins located in the Southern Hemisphere during rest indicated that they spent the majority of the time (85%) engaged in behaviors that can be considered clockwise. This is in contrast with many observations of sleeping/resting dolphins in the Northern Hemisphere that spend the majority of their time involved in counterclockwise activity. This observation leads to the possibility that the reason for preferential swimming biases in dolphins is the result of global forces rather than the result of the anatomy of the individual dolphins. Our observations also indicate that dolphins change overt behavior every 40 s, coincident with the respiration rate. The possibility is suggested that the salience of neural activity controlling respiration in the reticular system may effect/disrupt reticular attentional mechanisms, thus leading to the changes in overt behavior. It is hypothesized that this 40-s period may represent the possible attention span of the sleeping bottlenose dolphin.