California sea lions are champion deep-divers, withstanding
descents more than 300 meters deep. Now, a female California sea lion fitted
with a data logger (pictured) has yielded the sea lions' secret, scientists
report online today in Biology Letters. For decades, zoologists had suspected
that marine mammals such as seals and sea lions collapse their lungs to
withstand water pressures and endure deep dives. So scientists used the data
logger to keep track of the partial pressure of oxygen in the sea lion's
arterial bloodstream—a proxy to detect lung collapse—throughout her dives.
journal reference: Biology Letters