Abstract
Being able to tie their body into a knot is beneficial to some moray eels and other cylindrical vertebrates for various reasons, although not all morays’ tie knots. Knot tying can generate leverage for feeding activity by moving the knot up the body, and this leverage may be affected by knot type. Three types of knots are known to have been used by morays’ and this study further elucidates this behaviour and ability. Baited Remote Underwater Videos (BRUVs) were used to compare knot tying between the moray eels Gymnothorax prasinus and Gymnothorax prionodon in the Solitary Islands region, eastern Australia. Gymnothorax prasinus tied more knots overall and more types of knot than G. prionodon (five types vs one type, respectively). Both tied the overhand knot and this was the most common knot used by G. prasinus. The figure of eight knot was used two times more than the double overhand knot, being relatively wider and likely easier to move up the body. Gymnothorax prasinus also tied two undescribed knots, now called the ‘moray knot’ and the ‘morays banana knot’, which have more crossings and are bulkier, increasing potential for generating leverage. However, their uncommon use indicates costs may outweigh benefits of these more complex knots. Lower habitat complexity in deeper waters may influence differences in knot tying as G. prasinus were only recorded shallower than 40 m and G. prionodon mainly deeper. These findings further reveal the utility and complexity of knot tying in moray species and cylindrical vertebrates generally.
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Acknowledgments
The field work was conducted as part of NSW Department of Primary Industries (NSW DPI) marine ecosystem research under NSW DPI Ethics approval ACEC Ref 10/09. The analyses of the knot tying and writing of this manuscript were carried out in the author’s own time due to the more esoteric nature of this study in relation to NSW DPI core research. Individuals who have assisted with field work include Arthur Schultz, Rob Thorman, Nicola Johnstone, Brett Vercoe, Andrew Benson and Mike Davey. Thanks also to Jim Seager at SeaGIS for various support over the years and to Toby Waters for knot tying discussions and a loan of ‘Why Knot?’ by Philippe Petit, an inspirational knot tyer. Thanks very much to Des Pawson, one of the founders of the International Guild of Knot Tyers and owner of the Museum of Knots and Sailors Ropework who confirmed that he also could not find a name for the two knots and suggested I coin a name for them involving morays. Improvements to the manuscript were made from suggestions by colleagues at DPI: Dave Harasti and Nathan Knott and by the manuscript Reviewers.
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Malcolm, H.A. A moray’s many knots: knot tying behaviour around bait in two species of Gymnothorax moray eel. Environ Biol Fish 99, 939–947 (2016). https://doi.org/10.1007/s10641-016-0535-4
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DOI: https://doi.org/10.1007/s10641-016-0535-4