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Details of the physiology of such uniquely adapted mammals can be difficult to study on wild, uncooperative subjects. We are able to use our close relationship with the SLEWTHS sea lions to permit numerous highly specialized investigations into their unique physiological adaptations. One of the most interesting characteristics of marine mammals is their capacity to function as air breathers in a cold, aquatic environment. The SLEWTHS project has conducted many investigations regarding these adaptations including metabolic rate, heart rate, biomechanics, and blood flow.

Molting Dynamics:

SLEWTHS is currently studying the molting phenology of five of our six California sea lions, including Cali (a juvenile female). Results so far have shown that the sea lions tend to start molting in July and finish molting in November. The molt also progresses in a very clear pattern, starting on the ventral surface and the flippers, and progressing around the body until completion is reached on the dorsal surface. Future studies may include hormonal implications in molting and water temperature correlations with regard to timing of the molt. Policy recommendations may also be made as to when to collect fur for mercury content analysis in wild populations.

Comparing sea lions and human divers:

In March of 2001 two of the sea lions began participating in a study comparing dive physiology (including heart rate, blood lactate, and effects of instrumentation) between pinnipeds and humans. Some of the best human free-divers from Europe (including: Loic Leferme and Pierre Frolla), are participating in the investigation in Moss Landing to make comparisons side by side with our sea lions in the ocean, diving to depths of up to 100 ft.

Swimming Mechanics studies both in the pools and the open ocean are being used to study the effects of field instrumentation on the swimming and diving capabilities of sea lions. Comparisons will be made with instruments varying in weight, shape, buoyancy, and body placement. The results should help establish a calibration for field studies using instrumentation and provide direction in future instrument design.
Calibration for field studies:

Accurate calibrations are necessary to establish parameters for numerous techniques that are used in the field to study wild animals. This is inherently difficult to accomplish with wild animals, so the SLEWTHS sea lions have been used to study and calibrate various field research techniques including: stomach temperature, prey passage, respiratory rate and general equipment testing.
Updated November 2008