A wearable non-invasive device based on near-infrared spectroscopy (NIRS) can be used to investigate blood volume and oxygenation patterns in freely diving marine mammals, according to a study publishing June 18 in the open-access journal PLOS Biology by J. Chris McKnight of the University of St. Andrews, and colleagues.

The results provide new insights into how voluntarily diving seals distribute blood and manage the oxygen supply to their brains and blubber, yielding important information about the basic physiological patterns associated with diving.

In response to submersion in water, mammals show a suite of cardiovascular responses such as reduced heart rate and constriction of peripheral blood vessels.

But investigating dive-by-dive blood distribution and oxygenation in marine mammals has up to now been limited by a lack of non-invasive technology that can be used in freely diving animals.

The authors hypothesized that NIRS could address this gap in knowledge by providing high-resolution relative measures of oxygenated and deoxygenated hemoglobin within specific tissues, which can in turn be used to estimate changes in blood volume.

In the new study, McKnight and colleagues adapted NIRS technology for use on freely diving harbor seals to investigate blood volume and oxygenation patterns specifically in the brain and blubber, using a device that they dub the PortaSeal.

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