The Biological Pump (image) University of California - Santa Barbara Caption Shown are the links among the ocean's biological pump and pelagic food web. Light blue waters are the euphotic zone, while the darker blue waters represent the twilight zone. Credit Courtesy of the US Joint Global Ocean Flux Study Usage Restrictions None 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.