Worms that repair: reconstruction of tubes is faster than normal growth in Spirobranchus akitsushima (Annelida: Serpulidae)

Abstract

Marine worms of the family Serpulidae (Annelida) construct calcareous tubes that adhere to hard substrata. The tubes of the Spirobranchus kraussii complex have a flat projection, known as a ‘flap’, over the opening of the tube. In the present study, we examined the reconstruction growth rates of the flap of Spirobranchus akitsushima after artificial removal, compared with the normal growth rates (control), for approximately a month at a study site in Shirahama, Wakayama, Japan. Although the difference in the length of the flap on day 8 compared with the original length (before the removal treatment) was significant in the treatment group, the differences became nonsignificant after day 13. The flap growth rate was found to be higher than the growth rates of the tubes of other serpulid species, including Spirobranchus sp. 5 sensu Kobayashi & Goto (2021) of the S. kraussii complex, as reported in previous studies. In contrast, the length of the flap in the control group did not differ significantly during the survey period. These results indicate that the flap is more quickly reconstructed after removal compared with growth under normal conditions. Our findings imply that the flap may be of importance for the survival of S. akitsushima.