devorce and 401K

Cannot avoid devorce. One problem is although we have a joint banking account, we do not have much savings. However, since he's been an employee many years, he has saved quite amount 401K. I am wondering if his 401K is his own private propery? I am not that greedy, but after devorce, I need pay the house mortagage and raise the kids all by myself. Although I have a job, it is pretty hard for me.