Good Swimmers of Uniform Size (IMAGE) Brown University Caption Variations in sperm length, particularly in the tail (flagellum), indicate a lower concentration of sperm that swim well. Researchers apply the segmented line to measure the length of the sperm. Credit Jim Mossman Usage Restrictions With credit 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.