To gut black lug,you need to nip the head of the worm,or gently squeeze the worm until the head pops (sounds nice does`nt it) a few worms will gut themselves automatically as you pump them,unless you put them straight into a bucket of sea water.Gutting them will enable you to keep them in good condition for up to a week,if wrapped in newspaper and stored in a fridge (re-wrap after a day and they will be perfect)
I would`nt gut them if i was using them within 24 hours,as it`s always best to keep as much of the natural juices as you can.Kept any longer than 24 hours,and the bigger worms tend to blow up like balloons,and become very soft.Smaller worms can be kept in sea water for a few days,so long as they`re kept cool,and given fresh water every day.