Stroke with arrowhead

1Create Solid layer and add mask on it.

For closed shapes set mask mode to: none

2Apply effect Volna from Effects->irrealix->Volna

3In effect parameters unroll Mask1, in drop down menu Mask chose Mask1.

4Change Arrow Head End from None to Arrow1.

5Set Thickness value.

6Adjust Thickness Ramp.

7Choose Gradient Colors.

8Animate with Offset. Or With End.