  We extend the analytical arguments of Metlitski and Grover (arXiv:1112.5166)
to compute the entanglement spectrum and entanglement entropy of coplanar
antiferromagnets with $SO(3)$ order parameter symmetry. The low-energy states
in the entanglement spectrum exhibit the tower of states structure, as is
expected for systems that undergo spontaneous symmetry breaking. Our results
are consistent with numerical results on the triangular and Kagom\'{e} lattice.
