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Burst swimming (stroke and glide) has long been considered an efficient form of aquatic locomotion (Weihs, 1974). More recently, another form of intermittent locomotion, prolonged gliding, has been observed in several marine mammal species (Skrovan et al., 1999; Williams et al., 2000; Nowacek et al....
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.622.3361 http://jeb.biologists.org/content/205/24/3769.full.pdf |
| Summary: | Burst swimming (stroke and glide) has long been considered an efficient form of aquatic locomotion (Weihs, 1974). More recently, another form of intermittent locomotion, prolonged gliding, has been observed in several marine mammal species (Skrovan et al., 1999; Williams et al., 2000; Nowacek et al., 2001). In addition, in Weddell seals Leptonychotes weddellii, prolonged gliding has been associated with decreased diving metabolic rates (Williams et al., 2000). Thus, in addition to hydrodynamic adaptations and buoyancy changes, intermittent locomotory patterns probably play a significant role in energy conservation during diving (Williams, 2001). As a consequence, the aerobic dive limit of a species (ADL; dive duration associated with post-dive lactate accumulation) may vary according to the depth profile and swimming behavior during dives. The measured ADL (ADLM), or diving lactate threshold (DLT) as determined by blood lactate measurements (Butler and Jones, 1997) of emperor penguins Aptenodytes forsteri is 5.6 min (Ponganis et al., 1997). That ADL study involved relatively shallow dives (<50 m) of emperors foraging from an isolated dive hole. Depth profiles of these dives typically include descent to depth, travel at depth, hunting ascents to the undersurface of the ice to catch fish, and then return to depth for travel and eventual exit at the dive hole (Ponganis et al., 2000) Although shallow dives (<60 m) comprise about 60 % of all dives during foraging trips to sea, emperors also routinely dive to 500 m depth, and frequently have diving durations greater than the ADLM (Kooyman and Kooyman, 1995; Kirkwood and Robertson, 1997). Given the large diving air volume of penguins (Kooyman et al., 1973; Ponganis et al., 1999; Sato et al., 2002) and the potential role of buoyancy changes and intermittent locomotion patterns in affecting the magnitude of the ADL, it is unknown if swim behaviors during deep and shallow dives differ, and if the aerobic dive limit of |
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