Whales may be the most massive animals in the world, but siphonophores – relatives of jellyfish and corals – can be the longest, at up to 50 metres. On Wednesday evening the Science Museum in London is holding a 'Lates' event to stage the announcement of the discovery of one million new underwater species. The Tara research team will announce the findings following a two-and-a-half-year, 70,000-mile voyage across the Atlantic, Pacific, Antarctic and Indian Oceans, investigating marine ecosystems and biodiversity under the impact of climate change. Their talk will also include rarely seen footage of siphonophores