Why does my creature look like this when I try to skin it? I have a student who when trying to skin her creature, it looks like this. I am not sure why one half of it can be skinned while the other half can't get selected. Any help would be appreciated. 

http://www.pasteall.org/blend/37658

Thanks!!
Its because there is a Mirror modifier still unapplied on the mesh. Just click Apply for the Mirror modifier (While in Object Mode) and both halves of the mesh will be editable.