Plant-animal worms round themselves up in circular mills on the beach

Sendova-Franks, Ana; Franks, Nigel; Worley, Alan

Abstract

© 2018 The Authors. Collective motion is a fascinating and intensely studied manifestation of collective behaviour. Circular milling is an impressive example. It occurs in fishes, processionary caterpillars and army ants, among others. Its adaptive significance, however, is not yet well understood. Recently, we demonstrated experimentally circular milling in the marine plant-animal worm Symsagittifera roscoffensis.We hypothesized that its function is to gather the worms and facilitate the dense films they form on the beach to promote the photosynthesis of their symbiotic algae. Here, we report for the first time, to our knowledge, the occurrence of S. roscoffensis circular mills in nature and show that it is by no means rare. The size and behaviour of circular mills in their natural environment is compatible with our earlier experimental results. This makes S. roscoffensis a good study system for understanding the proximate and ultimate mechanisms of circular milling.

• Journal Article Type: Article
• Acceptance Date: Jun 27, 2018
• Publication Date: Jul 1, 2018
• Deposit Date: Jul 26, 2018
• Publicly Available Date: Jul 26, 2018
• Journal: Royal Society Open Science
• Electronic ISSN: 2054-5703
• Publisher: Royal Society, The
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 7
• DOI: https://doi.org/10.1098/rsos.180665
• Keywords: circular mills, collective motion, collective behaviour
• Public URL: https://uwe-repository.worktribe.com/output/864197
• Publisher URL: http://dx.doi.org/10.1098/rsos.180665
• Related Public URLs: http://rsos.royalsocietypublishing.org/content/5/7/180665.figures-only
• Additional Information: Additional Information : Electronic Supplementary Videos could be found at: http://rsos.royalsocietypublishing.org/content/5/7/180665.figures-only
• Contract Date: Jul 26, 2018