A rare snail found in just one lake in the UK started laying eggs on its six-hour journey from Wales to Kent, as a zoo joined a nationwide effort to save the species.

Glutinous snails are no bigger than a fingertip and used to be widespread across UK water ways.

It is thought habitat disruption and environmental changes reduced their population to such an extent that they are only now found in Llyn Tegid, a lake in Eryri National Park, also known as Snowdonia.