The invention concerns an ear tag for identifying and marking animals, said tagassociating a receiver button (1) by irreversible fitting of a finger (2). Saidbutton (1) comprises a head (13) wherein is provided a cavity (8) for receivinga punch (3) of the finger (2). The head (13) is secured to a shell (5) retaining thepunch (3) which is provided with an opening (6) for introducing the punch (3) insidethe button (1). The axial wall (7) of the retaining shell (5) delimiting said opening(6) is radially deformable. A chamber (11) is arranged between the head (13) andsaid axial wall (7) for receiving the latter (7) deformed under the effect of thepunch (3) passing through said opening (6).
