Is there a special tool for those to take them off and reuse them?

 

There is, but you don't need it. A pair of pliers and maybe a small screwdriver will work. You just squeeze the two ridges together and it will snap open. The screwdriver is to help it if it gets stuck.

Here's a discussion with pictures: https://www.jaguarforums.com/forum/x...-clamps-89769/

I replaced mine with standard screw type clamps when I did my radiator hoses. They work just fine if you don't get too aggressive when tightening. And much easier to use.