Backgroud Asexual reproduction via fission plays a vital role in the survival of the sea cucumber Holothuria atra . However, the energetic and nutritional mechanisms driving its regenerative capacity remain poorly understood. Method Fission was induced in the sea cucumber Holothuria atra by constricting the mid-body with a rubber band. Following fission, the resulting fragments were designated as anterior (A) and posterior (P) based on their original body orientation. The growth, oxygen consumption, ammonium (NH 4 + ) excretion rates and biochemical composition were then assessed in both anterior and posterior fragments at 10, 20, 30, 40, 50 and 60 days post-fission regeneration. Results Induced fission generated anterior and posterior fragments. Both fragments exhibited significant weight loss, with a 31.6% reduction observed by day 10. Routine metabolic rates (RMR) were elevated during regeneration, particularly in anterior fragments, which peaked at 1.06 ± 0.46 mg O 2 h −1 g −1 DW (dry body weight) by day 40. Simultaneously, increased ammonia excretion rates indicated a reliance on protein catabolism as a primary energy source (O:N ratio < 10). Despite these metabolic shifts, the proximate biochemical composition (levels of protein, lipid and carbohydrate) remained largely stable during the regeneration. An exception was a transient peak in specific fatty acids ( e.g. , C18:1n-9, MUFA) at day 30, which may be associated with membrane synthesis. Moreover, posterior fragments showed higher carbohydrate mobilization by day 50 ( p < 0.05). Conclusion These findings suggest that H. atra may maintain homeostasis during fission by modulating metabolism rather than depleting stored nutrients, possibly entering a hypometabolic state to conserve energy. This study highlights the resilience of H. atra to asexual reproduction stressors and underscores the need for further research on exogenous nutrient absorption during regeneration.
Wang et al. (Tue,) studied this question.