How can scientists tell how old animals are?

Question

For example, how do they know the Greenland shark is 512 years old (believed)?

In: Biology

Answer 1

Carbon dating is usually used in conjunction with other methods for a close estimate. All living organisms contain carbon-14, a radioactive isotope of carbon that comes from the sun’s rays interacting with the atmosphere and forming CO2 molecules which have a carbon-14 instead of a normal carbon-12. The CO2 is absorbed by plants for photosynthetis and animals eat the plants. When the organism dies it stops taking in the Carbon-14. The isotope slowly decays over time, following the exponential decay trend. By measuring the radioactivity of the fossil the scientists can tell how long it has been since the animal died