spiraling lines

[Sierra Rose]

I'm making a little film with seahorses. Their tails coil and uncoil as they move and I'm trying to find a way to keep the tail the same length as it does this. It escapes my eye right now and it doesn't have to be perfect, but I'd like to have a beginning model of how this goes to be a guide. Does anyone have any idea how to achieve this? I have coiled and uncoiled a string and measured the change in area so I have an idea of the proportion and I've tried to use the 3 point spline to make a model. I keep thinking there is another tool for this I'm not thinking of????? Thanks if you have any ideas.

Edit: My husband reminded me I could do just a little Fibonacci series of maybe 5 segments in differing positions to get the hang of the curves. And it works.