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

Sendova-Franks, A., Franks, N. and Worley, A. (2018) Plant–animal worms round themselves up in circular mills on the beach. Royal Society Open Science, 5 (180665). ISSN 2054-5703 Available from:

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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.

Item Type:Article
Additional Information:Electronic Supplementary Videos could be found at:
Uncontrolled Keywords:circular mills, collective motion, collective behaviour
Faculty/Department:Faculty of Environment and Technology > Department of Engineering Design and Mathematics
ID Code:37211
Deposited By: Dr A. Sendova-Franks
Deposited On:26 Jul 2018 10:49
Last Modified:30 Aug 2018 20:35

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