A big purple goodness, given many names, one of them would be a chickens kids with some fauna

I start out small, yet grow to be, a winding path that feeds the sea.

I run long and thin but within the walls, I thrive and scale without falls.

You're going to want this for my first four. My last three shares the same end as a turtle.

I drift with grace, no bones, no shell, A ghostly dancer in ocean’s swell. I sting my prey, yet mean no ill, With flowing arms, I float at will.