Paired Sperm (image) University of Arizona Caption These are paired sperm of the diving beetle, Thermonectus marmoratus. The darkfield microscopy image shows both heads and tails of the paired sperm, which is 0.25 mm long! Credit Dawn Higginson, University of Arizona Usage Restrictions This visual may only be used in conjunction with reporting/posting of this news release. Image/video credit must be included exactly as indicated. 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.