大象传媒

The coming and going of the tide dictates a lot of what goes on around Scilly. Bill Oddie goes down to the shore at an especially low tide - the spring tide - to meet Tegwyn and see what's been exposed on the beach. An eel grass bed that is usually underwater is now visible. Eel grass grows like a grass with its roots in the sand. Geese love eating it. Sandy shores are very difficult places for sea creatures to live because the sand shifts about. Eel grass stabilises the sand and provides a home for creatures such as brittlestars. The brittlestar has five arms - it uses three to hold on and two to feed, and swaps them over when it gets tired. Another echinoderm found here is the sea potato, a type of sea urchin that buries itself in the sand. Some of its spines are for digging.