Porpoise with Electronic Tag (image) Aarhus University Share Print E-Mail Caption The electronic tags, easily fitted on the back of a porpoise by suction cups, fall off after approx. 20-40 hours of use. Credit Photo: Lis Bach, AU Usage Restrictions May be used in relation to this news release. Share Print E-Mail 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.