Did you know that scientists can determine the age of a shark by counting the rings that form on its vertebra? Much the same as you can count the rings on a tree to tell its age. 
Enjoy our gallery of shark pictures below.
© Greenpeace / Ralf Kiefner
© Barry Peters
Campana, S.E. 2001. Accuracy, precision and quality control in age determination, including a review of the use and abuse of age validation methods. J. Fish. Biol. 59:197-242.