Check out Brilliant: http://brilliant.org/todayifoundout If you happen to like o→→Subscribe for new videos every day! https://www.youtube.com/user/TodayIFoundOut?sub_confirmation=1 Never run out of things to say at the water cooler with TodayIFoundOut! Brand new videos 7 days a week! More from TodayIFoundOut: That Time Snakes, Monkeys, Crocodiles, Rats, and a Gorilla Took Over a Ship https://youtu.be/OJHfAVjofbM In this video: When it comes to spiders, people generally know two facts about them- that you swallow around eight of them per year and that their blood is bright blue. Fortunately, the former is absolutely not true at all, the latter, on the other hand, is mostly correct. Want the text version?: http://www.todayifoundout.com/index.php/2014/09/true-spiders-blood-blue/ Sources: http://www.explorit.org/science/spider.html http://ednieuw.home.xs4all.nl/Spiders/InfoNed/blood.html http://www.wisegeek.com/do-all-animals-have-red-blood.htm http://animals.howstuffworks.com/arachnids/spider1.htm http://biology.clc.uc.edu/courses/bio105/circulat.htm http://www.findaspider.org.au/info/spiderblood.htm http://education-portal.com/academy/lesson/open-circulatory-systems-definition-lesson-quiz.html#lesson http://www.wisegeek.org/what-is-interstitial-fluid.htm http://www.rcsb.org/pdb/101/motm.do?momID=41 http://www.theatlantic.com/technology/archive/2014/02/the-blood-harvest/284078/ http://www.horseshoecrab.org/med/med.html http://dub130.mail.live.com/default.aspx?id=64855&owa=1&owasuffix=owa%2f http://en.wikipedia.org/wiki/Limulus_amebocyte_lysate http://blog.nativefoods.com/nativefoods/2012/02/the-horseshoe-crab-harvest-million-dollar-blue-bloods.html