emergency marine aquarium :-)

Hi

My son came back from the seaside at the weekend with a bucket full of
shells (like they do). Unfortunatley among them were about a dozen
muscles and two small crabs which were still very much alive!

We're going back to the seaside on saturday, so I'd really like to keep
them alive till then so I can re-patriate them. I've still got them in
his bucket, and, working on the principal that ANY water was probably
better than none, I've added some filtered tap water hoping that the
sand and other materials mixed in with the muscle clump will add a bit
of salinity.

Any advice anybody might have on keeping them going till the end of the
week would be gratefully recieved.

andy (involutary marine aquarium keeper)