This week, the world’s largest cruise ship set sail from Miami. Whilst a cruise holiday may be appealing to some, there is also a long history of disease spreading around the world via ships. Marnie and the panel take a look at the reasons why and the resulting impact on public health policies. It’s not just humans and microbes that are hitching a ride aboard sea vessels. Animals such as mussels can cling on to ship hulls, exposing previously pristine environments to potentially invasive species. We hear how scientists are tackling this problem with novel polymer lubricants. And we’re not done yet with marine creatures creating big issues. Professor John Parnell tells us the huge impact microscopic phytoplankton has had on Earth’s geology, and how the stuff in your pencils could actually be the bodies of long dead plankton... Plus, we explore the latest developments in rhino IVF, say ‘saluton’ to our Esperanto listeners and answer a question about going grey. And as Alabama uses nitrogen to execute a prisoner, we look at the science behind death penalty drugs. Presenter: Marnie Chesterton, with Yangyang Cheng and Philistiah Mwatee Producer: Sophie Ormiston, with Margaret Sessa Hawkins, Alex Mansfield, Dan Welsh, Harrison Lewis, Katie Tomsett and Jack Lee Production Co-ordinator: Jonathan Harris