No, it is not a lizard task. Despite them looking very much like they are a completely separate slayer task. There is no equivalent to them that you can kill as an alternative. So if you have a cave crawler slayer task from one of the slayer masters that assigns them, you will have to kill them. If you do not want to kill them, you will have to skip the slayer task. However, this ends your streak, and that is a pretty bad idea if you want to have a decent amount of slayer points in the future.