Ocular tentacle regeneration and associated malformations in Stramonita haemastoma (Gastropoda: Muricidae)

The present study aimed to elucidate the causal factor of tentacular malformations observed in Stramonita haemastoma. For this purpose, an annual, spatial and interspecific survey of the tentacular malformations was conducted in addition to the experimental semi-amputation of the tentacles of S. haemastoma. This study reports, for the first time, the occurrence of tentacular malformations in S. haemastoma collected for one year from the Bizerta Channel. Tentacle malformations were detected in 12 out of 17 Mediterranean and Atlantic coastal sites. Besides S. haemastoma, two sympatric muricid species (Hexaplex trunculus and Bolinus brandaris) also showed the occurrence of tentacular malformations. The experimental semi-amputation of the tentacles of S. haemastoma confirmed the capacity of regeneration in this gastropod; however, the process was often deficient and the neo-formed anterior segment was usually shorter, thinner and provided with a small ocellus. Sometimes, individuals were unable to regenerate a number of structures like the posterior segment and the ocellus, which may explain the tentacular malformations observed previously in S. haemastoma. This study provided new data about the incidence of tentacular malformations in marine gastropods. Our results further demonstrate the capacity of regeneration in S. haemastoma, which can be used as a new model in regeneration studies.