From a recent article:
Dolphins can perform complex feats of maths that defy human computer systems.
The finding has forced scientists to reevaluate how intelligent the animals are.
When hunting, dolphins blow 'bubble nets' - but are still able to use sonar - 'counting clicks' through the mass of bubbles.
The ability seems to prove that the animals can do complex 'nonlinear' maths calculations.
Human sonar systems would be baffled by the bubbles - but dolphins appear to have a mathematical ability to 'cancel them out.
'I immediately got hooked, because I knew that no man-made sonar would be able to operate in such bubble water,' says Tim Leighton, professor of underwater acoustics at the University of Southampton.
Leightons team have been attempting to unravel how dolphins can hunt - while effectively blinding themselves.
'These dolphins were either 'blinding' their most spectacular sensory apparatus when hunting - which would be odd, though they still have sight to reply on - or they have a sonar that can do what human sonar cannot …Perhaps they have something amazing.'
The answer appears to be a surprisingly complex command of maths.
'Dolphins have been observed to blow bubble nets when hunting prey,' say the researchers.
'Such bubble nets would confound the best man-made sonar because the strong scattering by the bubbles generates ‘clutter’ in the sonar image, which cannot be distinguished from the true target.
'The engineering specification of dolphin sonar is not superior to the best man-made sonar. A logical deduction from this is that, in blowing bubble nets, either dolphins are ‘blinding’ their echolocation sense when hunting or they have a facility absent in man-made sonar.'
The facility seems to be variations in the clicks, which allow them to 'see through' a net of bubbles that would baffle human sonar.
The ability implies a command of complex 'nonlinear' maths.
It's not the only surprising ability dolphins possess.
Dolphins can recognise themselves in mirrors and understand ideas such as 'zero' - an ability normally restricted to primates such as chimpanzees and humans.
These mammals recognize themselves in the mirror and have a sense of social identity.
They not only know who they are, but they also have a sense of who, where and what their groups are.