Board Thread:Naruto Discussions/@comment-26084508-20150916103812/@comment-734582-20150916123618

Probably for the purpose of identity. They're made from a ten-tailed beasts, so each has tails to represent that, and a different number to be unique among themselves.

GreatestSin wrote: considering that 5 bijuus have been equal to 50%-kurama i think that the tails are to show their strength ^_^ Well the Biju were part of Edo Tensei jinchuriki. It may not be as bad as that. Kurama believed the tailes represented strength, but Shukaku did not.