Variation in the markings on and shape of whale tail-flukes are often sufficiently
different between animals to be used to identify individuals. 
Here, we see a lot of Sperm whale tail-flukes and can testify that each differ,
some markedly. The photo mosaic illustrates some of the flukes we have seen.

Photo-identification of whale tail-flukes is a useful tool when studying whales.
Repeat observation of the same individuals allows us to track their movements and estimate
their age. This kind of information can be useful in scientific studies of their social
behaviour, habitat use, foraging behaviour, annual migrations and their survival.
If you want to find out more about photo-identification try following up these links:

http://azoresphotoid.blogspot.com/

http://europhlukes.maris2.nl/

http://www.seawatchfoundation.org.uk/docs/Photo-IDGuidelines.pdf

http://virtualology.com/aquatichall/whalesperm.com/

http://www.leidenuniv.nl/cml/ssp/projects/namsc/namsc.html