Abstract
Marine invertebrates exhibit an impressive regenerative capacity. Among these lineages, colonial ascidians possess the unique ability of whole‐body regeneration (WBR), in which a new adult (zooid) body is restored. Botrylloides species exemplify this regenerative capacity by regenerating new adults solely from vascular tissue within approximately 2 weeks after the complete loss of adults from the colony. Although WBR has been reported in some species of the Botrylloides genus, such as Botrylloides diegensis , Botrylloides violaceus , and Botrylloides anceps , this study provides the first insights into the WBR of Botrylloides jacksonianum . In this study, we examined and compared the WBR processes of B . jacksonianum , B . affinis anceps (hereafter referred to as B . anceps here), and B . diegensis . B . anceps displayed twin‐body regeneration, whereas B . jacksonianum and B . diegensis regenerated only one zooid each. Histological examination confirmed the presence of multiple vesicles formed from hemoblast aggregates during WBR, a phenomenon observed in other Botrylloides spp. The investigated species exhibited strong similarities in their WBR, with some variations in the overall process, indicating the presence of similar mechanisms underlying WBR. Understanding the intricacies of tunicate WBR contributes to our knowledge of regenerative biology and may offer valuable insights for regenerative medicine research in vertebrates.