Articles - 'a', 'an' and 'the'

HOW TO PLAY:

  • Choose the missing articles (a, an or the) in the spaces.
  • Click the button at the bottom to check your answers.
  • Press the "refresh" button on your browser to play again.

   A      a      an      The      the   
climate crisis may be posing existential threat to many species of shark. new study has revealed that the acidification of the world's oceans is causing sharks' teeth to decay. It is well known in scientific community that increasing ocean acidity is damaging calcified species like corals, molluscs, and sea urchins. This led marine biologists to research whether shark teeth are at similar risk. Lead author of study, Maximilian Baum, investigated whether "sharks that swim with their mouths open to ventilate their gills and have constant seawater exposure might also be vulnerable". He concluded that "even teeth of apex predators show visible damage under acidified conditions".

Baum and his colleagues analyzed 42 teeth from 10 blacktip reef sharks at aquarium in Germany. They placed teeth in two separate water tanks for eight weeks. salt water in one tank had pH level of 8.2, which is similar to current ocean averages. The water in other tank was more acidic, with pH level of 7.3. Baum found that teeth in the more acidic water had "visible surface damage". This included cracks and cavities, increased root decay, and structural deterioration. He said ongoing damage could impact how sharks feed in future. Such damage could potentially trigger "domino effects" across health of many marine ecosystems.

Back to the shark teeth lesson.

Share this lesson

More Free Sites by Sean Banville

Online Activities