Sharks, often called the top predators of the ocean, rely on their razor-sharp teeth to catch and consume prey. Unlike most animals, sharks continuously replace their teeth throughout their lifetime. However, a new study reveals that this natural advantage might not be enough to protect them from the growing threat of ocean acidification.
Ocean Acidification and Shark Teeth Weakness
According to researchers from Heinrich Heine University Düsseldorf (HHU), Germany, the rising acidity of seawater could make shark teeth more brittle and prone to damage. Despite being composed of highly mineralized phosphate, shark teeth are not resistant to long-term exposure to acidic ocean water.
Biologist Maximilian Baum, the first author of the study published in Frontiers in Marine Science, explained:
“Shark teeth are built for cutting flesh, not for resisting ocean acid. Our results show just how vulnerable even nature’s sharpest weapons can be.”
This discovery highlights how climate change and human-driven CO₂ emissions are silently eroding the survival tools of one of the ocean’s most powerful hunters.
From Root to Crown: The Extent of Tooth Damage
Ocean acidification occurs when the ocean absorbs excess carbon dioxide (CO₂) from the atmosphere, lowering its pH. The current average ocean pH is 8.1, but projections suggest it may drop to 7.3 by the year 2300—making the ocean nearly 10 times more acidic than today.
To study this effect, researchers collected over 600 discarded Blacktip reef shark teeth from an aquarium. After selecting intact samples, they incubated the teeth in tanks with two different pH levels—current conditions (8.1) and future projected conditions (7.3).
The results were striking:
- Teeth exposed to more acidic water showed visible cracks, holes, and root corrosion.
- Their surface structure became rougher, making the teeth appear larger but structurally weaker.
- The overall tooth strength was compromised, increasing the risk of breakage.
Professor Sebastian Fraune, senior author of the study, noted:
“This project began as a student’s bachelor thesis and grew into a peer-reviewed publication. It shows how curiosity can lead to meaningful discoveries about climate change impacts.”
Small Damage, Big Ecological Impact
While sharks can continuously replace their teeth, living in highly acidic waters could force them to spend more energy repairing or regenerating damaged teeth. For species like Blacktip reef sharks, which swim with their mouths open for breathing, constant exposure increases the risk of damage.
Even small cracks or surface changes may seem minor, but for predators that depend on strong teeth for survival, this could have cascading effects across entire marine ecosystems.
Baum emphasized:
“Maintaining ocean pH near today’s average is critical. Even moderate acidification could harm species with slower tooth replacement cycles or lead to long-term ecosystem disruptions.”
Why This Matters for Marine Conservation
This research is a powerful reminder that climate change impacts go beyond rising temperatures and melting ice caps. Ocean acidification can weaken the very tools predators rely on to hunt, potentially destabilizing entire food webs.
Future studies will need to examine how living sharks might adapt, whether through faster tooth regeneration or chemical changes in tooth structure. However, the message is clear: protecting our oceans from acidification is essential for safeguarding marine biodiversity.
📌 Reference
- Baum, M., Fraune, S., et al. (2025). Simulated ocean acidification affects shark tooth morphology. Frontiers in Marine Science. DOI: 10.3389/fmars.2025.1597592