Parasites aren't actually all bad – in fact, they may actually be a sign that a marine ecosystem is healthy. To learn more about the bizarre world of deep oceanic parasites, Jaida Elcock is joined by some parasitic experts.Subscribe: http://bit.ly/BBCEarthSub #BBCEarth #IntoTheDeep Watch more: Planet Earth http://bit.ly/PlanetEarthPlaylist Blue Planet http://bit.ly/BluePlanetPlaylist Planet Earth II http://bit.ly/PlanetEarthIIPlaylist Planet Dinosaur https://bit.ly/PlanetDinosaurPlaylistWelcome to BBC EARTH! The world is an amazing place full of stories, beauty and natural wonder. Here you'll find 50 years worth of entertaining and thought-provoking natural history content. Dramatic, rare, and exclusive, nature doesn't get more exciting than this.This is a commercial page from BBC Studios. Service information and feedback: http://bbcworldwide.com/vod-feedback--contact-details.aspx