They're a slimy PITA to mess with. They have sharp teeth and a nasty bite so I fling em out of the yak as quickly as possible.
Years ago, a buddy of mine was bitten on the hand by a moray while bug diving. Even though he was wearing dive gloves it did a lot of damage to both sides of his hand. When we got back to the dock a couple of hours later his hand was swollen and still bleeding alot so I drove him to the ER to get it checked and cleaned up. One of the ER docs said it was good he came in because morays have a septic bite that usually gets infected. It took quite a few weeks for my friend's hand to stop hurting.