Niabi Zoo will hold its annual Earth Day celebration, "Party for the Planet," from 10 a.m. to 3 p.m. Sunday at the zoo in Coal Valley. The event will focus on the many ways in which Quad-City residents can help the countless wildlife habitats that surround them on a daily basis. The zoo will distribute 150 conifer tree saplings for individuals to plant at home as well as 250 Niabi Zoo 50th Anniversary reusable grocery bags. Regular admission rates will apply.