The issue with this is that it can lead to an infection. I think it is a good idea for your kitty to see a vet. If it is a deep enough injury, he/she may need a few stitches.
That pic is blurred, but nonetheless does not look good. Better to have a vet check it and treat it now than to wait for it to possibly get worse and require even more cost and treatment. Please take it to the vet and let us know what happened.