Serpent swallows ball

Can anyone please show me how to animate a serpent swallowing a ball? That is, a cylinder being smoothly deformed as a sphere passes down it.

Many thanks for any help.

I forgot to mention … I can do it with bezier tapers moved with a hook but it won’t work in Unity, where I need it.

The way that I’d do it is use a ‘cast’ modifier and apply it’s shape keys as an animation.
Here’s the cast modifier

And how to use ‘apply as shapeKey’ on modifiers *** from min 17:00 to 31:00

Fantastic. Thanks Drawingis dead.

alternately, you could try a dynamic paint -> vertex group -> displace modifier