Sharks are some of the most fearsome predators in the ocean—but it is not just their bite that makes them deadly. With hundreds of razor-sharp teeth, arranged in rows and constantly being replaced, sharks have evolved one of nature’s most efficient feeding tools. Some species, like the bull shark, can have up to 300 teeth at a time, and they are continuously losing and regrowing them.
Tiger shark teeth (Credit: Ila France Porcher)
But a new study suggests that this toothy advantage may be under threat.
Ocean acidification from global warming
A team of German scientists has discovered that ocean acidification—caused by rising carbon dioxide levels in the atmosphere—could interfere with sharks’ ability to regrow their teeth, potentially making it harder for them to hunt and feed effectively.
Unlike human teeth, which are protected by gums, shark teeth are exposed directly to seawater. This makes them especially vulnerable to changes in the ocean’s chemistry, particularly shifts in pH levels.
Shark teeth damaged
To understand the impact, researchers placed 60 recently shed teeth from blacktip reef sharks into artificial seawater tanks. One tank had today’s average ocean pH of 8.1, while the other was more acidic, with a pH of 7.3, which is similar to conditions scientists predict could exist by the year 2300 if global warming continues unchecked.
After eight weeks, the teeth in the more acidic water showed significant signs of damage. The roots had corroded, the serrated edges had become more pronounced, and the overall structure of the teeth had been weakened.
“The damage we observed to enameloid and dentin layers underlines that even the typically more crystalline components of shark teeth are not immune to acidification,” the researchers wrote.
While increased serration might seem like it could improve cutting ability, the study warns it might actually make the teeth more likely to break. If sharks cannot regrow their teeth as quickly or strongly as before, their survival could be at risk—especially for species that rely on powerful bites to catch and consume prey.
Danger to the whole ecosystem
The findings raise concerns about how broader ocean changes might ripple through marine ecosystems, affecting not just sharks, but the entire food chain they help regulate.
As the oceans continue to absorb more carbon dioxide from the atmosphere, this research is a stark reminder of the dangers posed to marine ecosystems by global warming.
