So there's a lot of excitement about dolphins on BIG THINK these days. If we can figure out how to communicate with them, we can figure out how to communicate with the aliens (ETs) that are bound to be somewhere out there.
But here's one difference between dolphins and any ETs we'll ever find out about. Those cute, social mammals have no interest in and no capacity for leaving the place in which they live.
There's no dolphin technology worth talking about.
And, as far as we can tell, they're not dissatisfied with their natural existence. One thing we could conceivably learn from them is the secret of their contentment. But it's probably the case that it's just not given to us (by nature) to share their contentment.
Let's face it. We're aliens and they're not. We are profoundly dissatisfied with what nature gives us. That's why we're so technological and biotechnological. There are, for example, no dolphin transdolphinists, but there are human transhumanists.
We aren't completely at home in this world, which is why we imagine other places and other beings on other planets. We can imagine that they can save us (as Carl Sagan did) from ourselves.
So we'll have a lot more in common with any ETs that show up here through some high-tech method than dolphins do. And it's doubtful to me figuring out some way of sharing our experience with the mammals who live in the sea and nowhere else will help us much in communicating with our fellow aliens.