大象传媒

Wading along the edge of the Thames, Bill Oddie talks about how very few of its banks are natural in London - most are shored up by concrete or bricks. He's on one genuine wild bank, but its in danger of disappearing - not from development, but because of a sinister little creature. Something has made holes in the river bank - the Chinese mitten crab which can grow to the size of a small dinner plate. They come from China and appeared in the Thames about 100 years ago, probably arriving in the water ballast of cargo boats. The 'mitten' part of their name comes from their claws which are sort of furry, and that fur swells up in the water, making them look quite impressive. They cause an awful lot of damage along the river by making holes. This erodes the natural shoreline and the trees collapse. Bill hopes that the local cormorants and herons will eat the mitten crabs and keep them under control.