Figure 8.
Skin and tissue temperature measurements of a harbor seal (Phoca vitulina) in air and water at temperatures indicated by the dashed and solid line segments, respectively (a). Tissue temperatures were measured at 3 mm (shallow), 13 mm (mid), 23 mm (deep), and 42 mm (“core”), which included the blubber layer (<25 mm thick) and deeper tissue. The seal was allowed to equilibrate for at least one hour at each ambient temperature while recording measurements every 4 minutes. Adapted from Hart and Irving, 1959. The energetics of harbor seals in air and water with special considerations of seasonal changes. Canadian Journal of Zoology, 37: 447–457. © Canadian Science Publishing. The dive profile of a translocated juvenile northern elephant seal (Mirounga angustirostris) that dove continuously for 7 days (18 hours shown in figure) and experienced water temperatures between 5–16°C (b, top). Four consecutive extended surface intervals are marked with thick black bars along with the duration (in minutes) of the first and last extended surface intervals. Temperature profiles at three depths within the blubber layer (deep = red, mid = orange, shallow = yellow) reveal how the temperature gradient within the blubber layer (ΔTavg = average(Tdeep−Tshallow)) undergoes large variations across dives (b, bottom). The cyclical nature of diving also results in smaller fluctuations within dives that is not observed in the resting harbor seal in (a) .