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Yes—but only under some conditions and not uniformly across sharks. In a 2025 laboratory experiment, isolated blacktip reef shark teeth exposed to severely acidified seawater developed corrosion and visible structural damage. A separate 2022 experiment found that Port Jackson sharks responded differently: warming alone made teeth more brittle, while acidification combined with warming produced teeth that were more elastic and durable. The evidence points to a species-specific risk, not an imminent world of toothless sharks.
Why acidic seawater can affect a shark tooth
Ocean acidification happens when seawater absorbs more carbon dioxide. The resulting chemical reactions lower pH and change the availability of carbonate ions, making it harder for some mineralized structures to remain stable. A lower pH means greater acidity; it does not mean the ocean becomes a strong household acid.
Shark teeth and dermal denticles are mineralized tissues containing calcium phosphate compounds, including fluorapatite. Their chemistry makes corrosion plausible when exposure is sufficiently acidic and prolonged. Whether corrosion actually occurs depends on the species, the mineral structure, temperature, exposure time and whether the tissue is an isolated tooth or part of a living animal.
What happened to blacktip reef shark teeth at pH 7.3?
The clearest direct evidence comes from a 2025 Frontiers in Marine Science experiment on discarded blacktip reef shark teeth. Researchers incubated isolated teeth for eight weeks in seawater adjusted to pH 7.3 and compared them with teeth kept near pH 8.2.
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| Experimental feature | Blacktip reef shark study |
|---|---|
| Species | Blacktip reef shark |
| Material tested | Isolated, discarded teeth |
| Acidified treatment | pH 7.3, described as a projected seawater condition for the year 2300 |
| Control treatment | Approximately pH 8.2 seawater |
| Exposure duration | Eight weeks |
| Reported outcome | Corrosion-related changes in tooth shape and structure |
The acidified teeth showed morphological damage consistent with corrosion. Coverage by the Associated Press in 2026 described cracks, holes, corrosion at the root and broader structural degradation; that account reported more than 600 discarded teeth in the study. Study lead author Maximilian Baum summarized the result as: “We found there is a corrosion effect on sharks’ teeth.”
That is evidence that sufficiently acidic seawater can mark and degrade shark teeth. It is not evidence that every shark tooth exposed to today’s ocean will dissolve at the same speed. The teeth were removed from the animals, held continuously in a laboratory treatment and exposed to a pH representing a severe projected future condition.
Why the result does not apply identically to every shark
Sharks do not all build teeth the same way, and ocean stressors rarely occur one at a time. A 2022 Global Change Biology study of Port Jackson shark teeth illustrates how a different species and a combined stress treatment can produce a different outcome.
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| Port Jackson treatment | Observed tooth response |
|---|---|
| Warming alone | Teeth became more brittle and mechanically less resilient |
| Acidification plus warming | Greater elasticity and durability, with increased fluoride content and crystallinity |
The combined treatment used a 0.3-unit pH decrease together with a 3°C temperature increase. The authors interpreted the higher fluoride content and crystallinity as evidence that the sharks could alter biomineralization in a way that made teeth more resistant to corrosion.
This apparent protection does not cancel the blacktip result. It shows why a single headline outcome—“acid dissolves shark teeth” or “sharks adapt with stronger teeth”—is too broad. Species-specific mineral chemistry, temperature and biological regulation can push tooth properties in opposite directions.
What shark denticles add to the evidence
A 2019 study examined the dissolution of fluorapatite in shark denticles during chronic hypercapnia, the condition produced by persistently elevated carbon dioxide. Denticles are the tiny tooth-like scales covering shark skin. They and teeth are structurally and materially similar, so denticle dissolution supports the chemical plausibility of comparable effects in teeth.
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However, denticle results are supporting evidence rather than a direct measurement of tooth loss in every living shark. A surface denticle exposed to surrounding seawater is not the same experimental system as a tooth developing inside a mouth.
What pH 7.3 tells us—and what it does not
In the blacktip experiment, pH 7.3 was selected as a projected seawater value for 2300. It is therefore a severe, controlled scenario, not a claim that all present-day oceans are already at pH 7.3. The approximately pH 8.2 control represents the much less acidic water used for comparison in that experiment.
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Why living sharks may not simply become toothless
Developing teeth have some biological protection
Teeth forming inside mouth tissue are not exposed in exactly the same way as an isolated tooth placed in seawater. Tissue coverage, mineralization stages and the chemistry of the mouth can alter how much acid reaches a developing tooth.
Sharks replace teeth repeatedly
Many sharks continuously replace shed or damaged teeth. Replacement could reduce the effect of damage to an individual tooth, although it does not guarantee that replacement can keep pace with faster corrosion or with teeth that are mechanically weaker.
Wild populations face several pressures at once
Overfishing, habitat loss and changes in prey remain major threats to sharks. Acidification-related tooth damage would be one additional pressure, not a standalone explanation for future population changes. The available experiments do not establish how tooth corrosion would alter hunting success, survival or abundance in the wild.
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- Natural fossilized shark tooth necklace that dates back millions of years; mens necklaces for shark enthusiasts
- Made with real fossils, so no two shark teeth fossils are exactly alike in size or color; Pendants range from a creamy natural white to butterscotch with an average size ranging from 0.7 inches to 1 inch in height
- Cool necklaces for men with a one of a kind shark tooth pendant with a wire wrap setting
- Shark necklace with natural leather cord options ranging from 16 inches to 20 inches; Easy to use modern silver push button closure
- Classic simple unisex beach necklace for men and women; Perfect to wear on vacation or by the water
So, will climate change make sharks’ teeth weaker?
It can, under some combinations of conditions, but the direction and size of the effect are species-specific. The blacktip reef experiment demonstrated corrosion in isolated teeth at pH 7.3. The Port Jackson experiment found that warming alone reduced mechanical resilience, while acidification paired with warming was associated with increased elasticity, durability, fluoride and crystallinity. Together, the studies support a real experimental risk without supporting one universal forecast for all sharks.
Bottom line
Ocean acidification can damage shark teeth, especially under severe and prolonged exposure. The strongest direct result is the eight-week blacktip reef shark tooth experiment at pH 7.3, but the contrasting Port Jackson findings show that sharks may respond differently through their own mineralization processes. These results justify concern and further study—not a prediction that modern oceans will soon contain toothless sharks.
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