Around 200 baby spiders have already been released at the RSPB's Strumpshaw Fen reserve near Norwich.
Ecologist Dr Helen Smith said: 'Most invertebrate groups don't receive a lot of conservation effort.
'The ones that tend to receive the attention are the big and spectacular ones ... this is very much the case with great raft spiders.
'They're big, they're beautiful and they have to fly the flag for other species.'
