Scientists had previously discovered the dolphins of Cardigan Bay are very unique, thanks to their voices.
In 2007, the creatures were studied by marine scientist Ronan Hickey of the University of Wales in Bangor, alongside experts from the Shannon Dolphin Foundation in Ireland.
The study recorded and analysed nearly 1,900 dolphin whistles in the Irish Sea to conclude the Welsh dolphins were truly unique.
Dolphins communicate by using a series of whistles and clicks, as well as barks and groans.
At the time of the research, Dr Simon Berrow of the Shannon Dolphin and Wildlife Foundation said: “Whistles are important to dolphin communities and individuals for recognition purposes.
“Calves are through to learn whistles of their mothers, and therefore that could mean whistles are evolving.