Identifying the mast substrata
To identify the substrata of Dyopedos bispinis masts, underwater observations were performed during 10 dives, and the numbers of masts attached to different types of substrata were counted inside a 0.2-m×0.2-m square frame. For a more detailed assessment, all masts inside 2 survey frames were collected in jars using forceps and a trowel and examined by binocular microscopy. Subsequently, the proportions of masts associated with each substratum were defined, and the substratum was defined for approximately 350 whips. When in focus (210 masts), the substrata were also identified from photos (see above).