You’d do the same if you had an octopus on your blowhole!
When I photographed the frantic battle between one of Port Phillip’s bottlenose dolphins and an octopus near Portsea, I had no idea that this could have been life or death – for both of them.
You can make out some tentacles of the octopus flailing around on the dolphin’s back. (It was a while ago and taken on a film camera which is why the image is so grainy.)
The dolphin continued to leap and somersault until the eight-legged hitch-hiker was dislodged.
The antics only settled once the octopus was well and truly gone.
I suspect this octopus managed to free itself enough to climb on to the dolphin’s head and blowhole – turning it from prey into a potentially life-threatening problem for the dolphin.
Octopus tricks of camouflage or hiding under the sand are no match for dolphins equipped with “sonar vision” and four rows of very sharp teeth to capture their prey.
Dolphins occasionally do die from trying to eat octopus. In 2015 a dolphin in Bunbury in Western Australia was found dead on a beach. Dr Nahiid Stephens, a pathologist from Murdoch University, found that the dolphin suffocated from a tentacle lodging on its larynx. The octopus was over a metre and a half across and was simply too big for the dolphin to swallow.
This understanding helps to explain why dolphins vigorously shake, throw and smash their octopus prey as if they are playing a sadistic game. It’s a behaviour that both kills the octopus and breaks it into pieces easier to swallow.
Dolphins don’t have ‘cutting teeth’. Their teeth are all like sharp pegs, perfect for grabbing prey but not for biting bits off. They also wear the front few teeth down digging in the sand for prey.
The video from Dr Kate Sprogis and colleagues from Murdoch University’s Cetacean Research Unit shows a dolphin ‘preparing’ an octopus for eating.
We have observed the outer mantle of cuttlefish floating on the water, still pulsing the iridescent colours of defence. I’m sure the other parts would have been in a dolphin stomach.
So it can risky being a dolphin – as well as being an octopus. And yes – I would jump around just like that if I had an octopus on my blowhole!
By Jeff Weir OAM, Executive Director, Dolphin Research Institute.