van der Schoot, R.J.

Appendix S1.Photographic host records of Petaloconchus sp.

Figure S1. Agaricia agaricitesat Bonaire (2019).

Figure S2. Agaricia humilisat Curaçao (2021).

Figure S3. Agaricia lamarcki at Curaçao (2021).

Figure S4. Cladopsammia manuelensis at Curaçao (2017).

Figure S5. Colpophyllia natansat Curaçao (2021).

Figure S6. Diploria labyrinthiformisat Curaçao (2021).

Figure S7. Eusmilia fastigiataat Curaçao (2014).

Figure S8. Madracis auretenraat Curaçao (2021).

Figure S9. Madracis decactisat Bonaire (2019)

Figure S10. Madracis senariaat Curaçao (2021).

Figure S11. Madracis senariaat Bonaire (2019).

Figure S12. Meandrina meandritesat Curaçao (2021).

Figure S13. Millepora alcicornis at Curaçao (2021).

Figure S14. Millepora complanata at Curaçao (2015).

Figure S15. Montastraea cavernosaat Bonaire (2019).

Figure S16. Orbicella annularisat Bonaire (2019).

Figure S17. Orbicella faveolataat Curaçao (2021).

Figure S18. Orbicella franksiat Bonaire (2019).

Figure S19. Porites astreoidesat Curaçao (2021).

Figure S20. Pseudodiploria strigosaat Curaçao (2021).

Figure S21. Siderastrea siderea at Curaçao (2021).

Figure S22. Stephanocoenia intersepta at Curaçao(2021).

Figure S23. Unidentified dead coralat Curaçao (2021).

Reef-dwelling Christmas tree worms (Spirobranchus spp.) are common coral associates. Their calcareous tubes are usually embedded in the coral skeleton and can be closed by an operculum. Tubes not overgrown by coral tissue either remain bare or become covered by algae. Despite their widespread distribution, high abundance and striking appearance, little is known about the impact of these worms on their hosts. We quantifed visible coral damage caused by Spirobranchus in Curaçao (Southern Caribbean) and found that 62.6% of worm opercula (n = 1323) caused abrasions and tissue loss in their hosts. Filamentous turf algae, known to be potentially harmful to corals, covered 76.9% of the opercula. Examination of the six most frequently inhabited host species showed a variation in the damage percentages, although this was independent of the presence of epibiotic algae on 78.4% of all opercula. Since injured corals are more susceptible to diseases, the overall negative impact of Spirobranchus worms on their hosts may be more severe than previously assumed.