The northern elephant seal(Mirounga angustirostris), having faced near extinction in the early 1900s, when it was hunted for blubber for lamp oil, is a recovery success story. And science is discovering some pretty amazing things about the largest pinniped's diving and breath holding capabilities. Not to mention their ability to fast for a weeks on end.
Elephant Seal Viewing Points
With a population of over 150,000, elephant seals haul out to rest on beaches all along the California coast, sometimes creating problems. The seals have become a regular tourist attraction along the California coast, where breeding colonies at Ano Nuevo, Point Reyes National Seashore and San Simeon, lure visitors to watch 4,000 pound bulls fight for territory on the beaches while nearby females give birth and nurse their young.
How They got Their Name
The name elephant seal comes from the large nose that bulls develop which is inflated to produce a rumbling sound that warns away competitors during breeding season. But it is not the proboscis that makes the elephant seal really unique.
Deep Diving and Breath-holding
Able to stay on land for extended periods of time, the elephant seal can also dive deeper than many of the great whales. They stay underwater longer as well. Using TDRs (Time Depth Recorders), northern elephant seals were tracked diving to 1,503meters The longest dive time was 67 minutes. By 4 months of age, pups are diving to more than 500meters and staying under for up to 20 minutes. At sea for 2-4 months at a time, their lives resemble that of the whales, sleeping on the surface or underwater, diving to feed and travelling great distances.
Then there is the breath-holding. In addition to staying under water for an hour, elephant seals commonly hold their breath for 20 minutes at a time while sleeping. And drop their heart rate by as much as 70% during sleep. These energy conserving strategies serve them well during the months at sea and while hauled out on land.
Fasting Behavior
Elephant seals do not eat when they are on land. Females haul out to give birth and stay on the beach with their pups for a month. Mother loses up to 40% of her bodyweight and the pup gains an equal amount. The males holding a territory during the breeding season also do not eat. In fact the entire life history of the elephant seal is a fasting and gorging cycle, eating nearly constantly while at sea then coming to land and fasting while breeding or molting.
This fascinating species is one of the oldest seal species in the world. Back from near extinct this is a great wildlife conservation story.
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