Dominic So (’27)
A shark cries because it has no teeth.
When you envision a shark, you may imagine something straight out of Jaws—powerful fins, large gills, and iconic, razor-sharp rows of teeth. You might even own one of these teeth in the form of a bracelet or necklace. However, the shark’s most striking feature may be in danger: recent studies show that shark teeth are at risk of erosion amidst climate change and ocean acidification.
Ocean acidification refers to the gradual lowering of the ocean’s pH as increased amounts of carbon dioxide are absorbed into the ocean. The ocean is known for being a carbon sink: it is capable of taking in excess carbon dioxide from the atmosphere, much like trees and plants. Given the sharp uptake in the burning of fossil fuels, there are more greenhouse gases in the atmosphere and the ocean has absorbed enormous amounts of carbon dioxide. This may appear to be helpful to lessen global warming, but as carbon dioxide enters the ocean, a series of chemical reactions occur, producing high quantities of hydrogen ions. These hydrogen ions lower the pH of the ocean and decrease the number of carbonate ions available. Carbonate ions are necessary for a variety of marine life, such as mollusks, coral, and crustaceans, as they form shells and protective exteriors. Yet ocean acidification’s effects are expected to impact far more than those animals alone. Hydrogen ions are also known to erode mineralized material over time, which shark’s teeth happen to be made out of. With this knowledge in mind, researchers from Heinrich Heine University of Düsseldorf in Germany were curious about the effects of ocean acidification on shark teeth.
Researchers collected 600 fresh, naturally-shed teeth from blacktip reef sharks at the Sealife Oberhausen, an aquarium in Germany. From these teeth, they selected 16 that were undamaged and 36 with limited damage. These samples were placed into two tanks with different pH levels: one tank with a pH of 8.1, which is similar to the current pH of the ocean, and one tank with a far more acidic pH of 7.3, the projected pH of the ocean in 2300 if the current rate of carbon emissions persists. The teeth placed in the tank with a pH of 7.3 showed significantly more signs of damage, including root corrosion, surface cracks, and structural degradation. It’s important to note that the study is limited: live shark teeth may remineralize or be replaced at faster rates.
Nonetheless, the study serves as a harrowing reminder of climate change’s ability to wreak havoc on our oceans, which provide essential resources. Sharks rely on their teeth to survive: if they were to erode and replace at faster rates, sharks would burn through far more energy than they already do. This would fundamentally alter their feeding efficiency and weaken the ocean’s apex predator, leading to trophic cascades that negatively affect the rest of the ecosystem and offset its balance.
The effects of climate change, and subsequently ocean acidification, inspire a sense of urgency. The idea of toothless sharks may instill panic—and for good reason. At this time, the health of our oceans and ecosystems lie at stake. But, not all hope is lost. Sharks can keep their teeth and Earth can be protected through intense conservation efforts. Whether or not that happens is for us to decide: the power to save our planet’s future is in our hands.