Dolphins Protect Swimmers

This seems to be a common tale, if somewhat un-verifiable that dolphins protect people from sharks. Is there any evidence behind this behaviour (specifically the protective motive as opposed to curiosity etc), and if so, can anyone speculate as to why this could be the case? I see no reason why they would recognise, let alone defend other mammals.


The motive is simple enough: Dolphins and sharks are enemies, and so dolphins will try to kill or chase away sharks whenever they can. If that happens to benefit humans in the vicinity, good for them, but that needn’t be the reason why they’re doing it.

I trained bottle-nosed dolphins for many years in captivity and never saw them lift a flipper to help a human being… but I wouldn’t really expect them to. They’re in captivity.

I have seen dolphins be quite aggressive towards humans in the water, especially a belligerent male looking for a mate.

Do wild dolphins actively try to help swimmers in trouble? I’ve heard those stories too, but I’ve never spoken to anyone who has witnessed it.

Herodotus wrote about it.

This doesn’t mean it’s true, although the story does mention that Periander was very skeptical - a natural reaction which, in my opinion, makes it just a twist more likely.

When I was doing my time of dolphin training, one of the bosses had this hypothesis: Dolphins are known to be playful critters who are likely to push people around in the water because maybe they’re just playing. But they’re just a likely to push a drowning swimmer farther out to sea as they are to push a drowning swimmer towards the shore.

And of course, the drowning swimmers that they just happened to push to shore are the only ones whose stories you’ll ever hear.

We always got a big laugh every time we talked about John Lilly and his cosmically enlightened dolphin theories.

Personally, I think dolphins are smart enough and altruistic enough that any individual dolphin might actively, knowingly, and deliberately save or protect a human swimmer. I think it’s perfectly plausible that this might happen from time to time. But they also might not. Those drowning swimmers whose stories you hear were the lucky ones.

OTOH, I did see one of our captive dolphins play a practical prank on someone (to-wit: me) that was definitely and unambiguously deliberate, knowing, and intentional.

Well, there was THIS today.

From that article:

Well, duh! Of course those dolphins knew that! Dolphins are telepathic, didn’t you know?

I dunno. However-

Greek myth held that the first dolphins were sailors transformed by Dionysus to save them from drowning. This was the explanation for why dolphins liked people so much and hung around boats.

I know Melville mentions dolphins in Moby Dick. He calls them the “huzza porpoise” (made no sense to me until I realized he meant he archaic cheer usually spelled Huzzah!). I know he says that they are friendly, will do tricks for food and that it is considered bad form and bad luck to kill one. I can’t recall if he says they save drowners.

If nothing else, dolphins are serviceable flotation devices. I could see a few sailors gaining extra time above-water by curious dolphins. That might not mean that they’re actively trying to help, just that they happen to do so.