The climate crisis may be an existential threat to sharks. A new study shows that the acidification of the world's oceans is decaying sharks' teeth. It is well known among scientists that increasing ocean acidity is damaging species like corals and shell-dwelling sea creatures. This led biologists to look at whether shark teeth are at similar risk. Researcher Maximilian Baum investigated whether sharks that swim with their mouths open and have constant exposure to seawater "might also be vulnerable". He concluded that "the teeth of…predators show visible damage".

Baum analyzed 42 teeth from blacktip reef sharks at an aquarium in Germany. He put the teeth in two separate water tanks for eight weeks. The salt water in one tank had a pH level similar to current ocean averages. The water in the other tank was more acidic. Baum found that the teeth in the more acidic water had visible damage. This included cavities, root decay, and structural deterioration. He said ongoing damage could impact how sharks feed. He added that such damage could potentially trigger "domino effects" across many marine ecosystems.