Why are some jumping spiders so colorful?

Backed by Lisa Hillson, Jeremiah Eck, Daniel Zurek, Robert Hillson, William Stysiack, Ewald Weisschedel, Eirik Søvik, Malcolm L, Maria Fernanda Cardoso, Bill & Susan Morehouse, and 80 other backersJulia Becerra, Asa Farnham, Gail And Dick, Anthony, Carolyn McCauley Morehouse, Joe Syage, Camille Meslin Auclair, And1, Yagiz Alp Aksoy, Donald Marron, Emilie Snell-Rood, Nathan Clark, Sarah Papperman, Mary-Frances Beesorchard, Felipe, Jim Heffernan, Ron Rutowski, Dhiala, Diana Matthias, Sarah Teichert, Thomas Shahan, Ben Fanson, Lisa Berg, Kevin Wills, Sarah Henry, Pat Monahan, Rowan McGinley, Stella Chung, Nathan Dappen, Kate Feller, Todd Huffman, Korina Abbott, Michael Ferro, Ellen Weisschedel, Oscar Jasklowski, Ktwo Reed, Kate LeCroy, Esmeralda Martinez, Alan Chen, Kim Biddulph, Brian Counterman, Misha Penton, Nicholas Saleh, Carlos Funez, Susan Villarreal, Lindsay, Celia Hanss, Jacob Sahertian, John Schampel, Arianne Cease, Matt Shawkey, James Walters, Melissa Ross, Avery Bird, Natalie Roberts, Eloise Deaux, Margaret Coulombe, Paul Burke, Cristy Gelling, Libby Larson, Tonya Van Leuvan, Eden, Emily Burdfield-Steel, Emily Hornett, Heidi, Alberto L. López-Torres, Miya Hewett Warrington, Adrian Smith, Marlene McJanda, Paul Gasser, Russell Ligon, Leslie Nitikman Sokolow, Marta Wells, Ryan Lower, Tim Park, Lee Jaszlics, Sara Mae, Ruthie Arbeiter, Cindy Wu, and Ann Hedrick