A Shark’s Tooth 

Dentists tell their patients to avoid acidic foods and beverages to prevent tooth decay. 

This won’t be an option for sharks in the future. 

Researchers in Germany recently found that ocean acidification, driven by human carbon dioxide (CO2) emissions, could leave the ocean’s apex predator with brittle, corroded teeth.

“Shark teeth … are still vulnerable to corrosion under future ocean acidification scenarios,” said lead author Maximilian Baum of the new study in a statement. “They are highly developed weapons built for cutting flesh, not resisting ocean acid. Our results show just how vulnerable even nature’s sharpest weapons can be.” 

For the study, the research team tested the effects of future acidified oceans by incubating discarded teeth from blacktip reef sharks in seawater tanks. One tank matched the current ocean average pH of 8.1, while the other simulated the predicted pH of 7.3 by the year 2300 – an almost tenfold increase in acidity.  

After eight weeks, the dentures in the acidic tank showed “visible surface damage such as cracks and holes, increased root corrosion, and structural degradation,” explained senior author Sebastian Fraune in the statement. 

This is quite concerning, considering that the predator’s teeth are made of tough, mineralized phosphate.  

And even though their teeth can grow back when lost, researchers caution that this might not be enough if tooth loss outpaces regrowth. Meanwhile, some species must swim with their mouths open to breathe, making exposure to acidic water constant. 

The findings underscore increasing concern about how climate change is threatening the world’s oceans and marine ecosystems, prompting calls for reducing CO2 emissions to stabilize ocean chemistry and protect marine life. 

The researchers said their study mainly focuses on non-living tissue and noted that the situation might be “more complex” in living sharks.  

Baum hopes that sharks will eventually adapt to their changing environment, an optimistic prediction shared by other marine scientists.  

“It will be interesting to see in future studies if the damage to teeth seen in studies like this one results in a functional effect on a tooth’s ability to do its job,” Lisa Whitenack, a shark tooth specialist at Pennsylvania’s Allegheny College who was not involved in the work, told the Guardian. “…(and if) damaged teeth can still cut or puncture prey.”