Many animals, especially insects and deep sea marine species, produce light to send signals to those around them. This is called bioluminescence. In this clip from the 1973 CHRISTMAS LECTURES "The languages of animals", Sir David Attenborough performs simple chemistry to show how some animals put on these vibrant displays. Subscribe for regular science videos: http://bit.ly/RiSubscRibe This video is from our 2017 advent calendar. Watch the full series here: https://www.youtube.com/playlist?list=PLbnrZHfNEDZyvS5Cx-aRTX-Y8IBJCNmYm Or watch the full lecture here: http://www.rigb.org/christmas-lectures/watch/1973/the-languages-of-animals/foreign-languages?utm_source=youtube&utm_medium=social&utm_campaign=2017_advent&utm_content=description The Royal Institution 2017 advent calendar ‘Transmissions Through Time’ looks through the lens of CHRISTMAS LECTURES past to share the best demonstrations around the science of communication. From Attenborough and Sagan to Woollard and Fong, we revisit old favourites and find new gems to bring you a little gift of science every day in the lead up to Christmas. http://bit.ly/RiAdvent17 The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter