Invasive signal crayfish, shags, night-shining clouds

This week in the Planet Earth Podcast: Richard Hollingham finds out why the American signal crayfish is driving out one of the UK's native species; in our latest audio diary, Hannah Grist from the University of Aberdeen talks us through her research on European shags; and what noctilucent clouds tell us about our changing climate. Like this podcast? Please help us by supporting the Naked Scientists