how long can you keep sandcrabs ?

[robsue]

just wondering how long other people have kept sandcrabs, usually i only keep them for 4 days, but i have pots in the water, will check mon/tues/wed as i need a good feed on sunday for relatives....
will they last mon till sunday? will they last longer if they are cleaned before cooking?
just that im busy later in the week picking up rellos etc for wedding sat

thanks in advance for any information
cheers
Robsue