Smithsonian Magazine —
Male narwhals grow spiraling tusks throughout their lives that can reach lengths of up to ten feet. Now, analysis of these tusks reveals narwhals in the Arctic are altering their diets as climate change reduces the extent of sea ice. Warming and fossil fuel pollution may also be contributing to a large increase in concentrations of the toxic heavy metal mercury accumulating in the whales’ bodies, reports Molly Taft for Gizmodo.
The research, published last month in the journal Current Biology, looked at the chemical composition of ten tusks from whales killed by Inuit subsistence hunters off the coast of northwest Greenland, reports Ellie Shechet for Popular Science.
Since a narwhal’s tusk, which is actually a specialized tooth, grows in annual layers like the rings of a tree trunk, researchers can study the layers to look back in time, reports Matt Simon for Wired.
“Each of the individual layers in a tree gives you a lot of information about the condition of the tree in that year of growth,” Jean-Pierre Desforges, a wildlife toxicologist at McGill University, tells Gizmodo. “It’s the exact same way with a narwhal tusk. We can count up [the layers] and get a number on how old the animal is, and we can link each individual layer to a date in time, broadly speaking, to a year. If the animal is 50 years old, we can count 50 layers in a tusk, and date it back all the way to 1960.”