Until recently I attributed Dusty's approaching from behind to predatory behaviour. But the fact that she does not come to the pier at low tide does cast a light from a different angle on her motivation.

At low tide the area around the pier becomes very shallow, no more than knee deep. I can just swim there as my way of propulsion needs little draught and so can Dusty. But at a price: her dorsal fin is showing. And she knows this and also that this tells her whereabouts. In normal circumstances she always has an escape route. Down under it's hard and usually even impossible to track her. In shallow water she is exposed.

Dusty has very often overtaken me, left, right, under and occasionally, when I'm below, above. When she comes from an opposite angle she likes to swim by and circle me, seeking also to be behind me. She knows I'm not food, which makes predatory motives less likely.

But she's curious and she can probably tell more about me than I'm aware of myself as she can listen straight through me. My body is made up for about 60% out of water, so with her sonar she can 'see' my bone structure and organs.

Just imagine you could! Wouldn't it be fascinating to have such an intimate, revealing view on your fellow human beings, particularly in where this implicates predictions? But on the other hand, wouldn't you feel more then naked to the all-seeing eyes of those same fellow human beings?

Dusty knows human beings have no sonar. But she does not know what we can see. And with a brain like ours it would not be unlikely for her that we are capable of the same kind of observations she can do. So she tends to avoid our direct eyesight so she can study our bodies at leisure without presumably being scanned herself.

But not all of Dusty's awareness is hidden inside her brain. She has a body too and likes to have attention and even be caressed. But she plays hard to get. From the steps down the pier she keeps the critical distance of just within reach and just without. In the water similarly, at a depth your snorkel is just out of air reach.

This is not science, it's a train of thought that may arrive at some station one day, but I'm free to venture credible theories. So you won't read me musing that dolphins are trying to convince us to, like they did some fifty million years ago, return to the ocean.