Running with the pack (VIDEO) Princeton University This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption Rod-shaped bacterial cells of the species Myxococcus xanthus cooperate by forming packs to hunt for food and build structures called fruiting bodies, which aid in survival. When two such swarms encounter each other, the resulting pileup of cells creates sites, called topological defects, at which rods can climb on top of each other to construct the next layer of the fruiting body. The colors represent the various swarms of cells. Credit Katherine Copenhagen, Princeton University Usage Restrictions Video credit: Katherine Copenhagen, Princeton University License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.