Featured Image Credit: earthspacecircle.blogspot.com
By Eva Gruber
Narwhals consistently rank among some of the most magical animals in the ocean. However, despite their popularity relatively little is known about their basic biology and natural history, due to their rather cryptic nature and occupation of remote and extreme environments. The expense and effort of expeditions to their region of the world are very costly. Thanks to recent studies conducted by the University of Washington’s School of Aquatic and Fisheries Science, we now have a better understanding of how narwhals navigate their Arctic home waters.
Narwhals are the only cetacean that spends all of its life in the frigid waters of the Arctic Ocean. They are highly specialized, having evolved many adaptations that have allowed them to survive and thrive in this unforgiving environment. Migrating thousands of miles from shallow bays and fjords in the High Arctic where they spend their summers, the majority (80-90% of the total population) returns to Baffin Bay for the winter. Despite winters being long, freezing, and lacking sunlight, the narwhals are highly active – winters are the time for feeding and breeding. Oh la la.
Polar scientists have long wondered how narwhals, in the dead and dark of the Arctic winter, can survive. How could they possibly find enough food? Narwhals dive to the sea bottom, often up to 5,000 feet deep and for up to 30 minutes, finding and eating their favorite winter prey – fatty, energy-rich Greenland halibut. Winter is when narwhals consume most of their yearly diet. Eventually, they must surface to breathe – but how do they find open areas of water free from ice cover?
The answer lies in the narwhals remarkable ability to “see” with sonar, underwater. Placing hydrophones in strategic locations around Baffin Bay, Dr. Kristin Laidre was able to listen to their use of echolocation. Their findings show that the narwhals use high-frequency clicks – too high-pitched for human ears to detect – like a flashlight, flashing on and off in their dark waters. With each click representing a snapshot, they are able to construct larger pictures of their underwater environment. The resolution of these pictures is likely the most accurate of any cetacean in the world, except for perhaps the beluga whale.
The clicks are produced by phonic lips at up to 1,000 clicks per second, a special structure in their head located below the blowhole, that is similar to our nasal cavity. The tissues in the phonic lips vibrate and can consciously be controlled by the narwhal (and other cetaceans). As the whale releases sound with its phonic lips, it picks up the returning signal through fatty pads in the lower jaw and is able to translate the echo as sensory information.
The researchers believe that the narwhals use a tighter beam of sound, much like an adjustable flashlight, to locate a distant object such as a polynya (hole in the ice) or halibut. As it gets closer to the object it might widen the beam for greater resolution, in much the same way that other echolocating animals (like bats) have been observed.
Narwhals have long been seen as mystical creatures, as far back as the time of the Vikings when their 6-to-9-foot long tusks were brought back to Europe with stories of unicorns. Finally, with the benefits of technology and science, we are revealing their secrets and natural history before climate change has a chance to negatively impact their populations.
Read the story covered by The New York Times.