AUTHOR=Liu Zerui , Zhao Xinye , Zhang Jia , Guo Yu , Yu Gang , Ma Zhenhua , Qin Chuanxin TITLE=Temperature modulates bimodal reproduction and energy allocation in the sea urchin Tripneustes gratilla JOURNAL=Frontiers in Animal Science VOLUME=Volume 6 - 2025 YEAR=2025 URL=https://www.frontiersin.org/journals/animal-science/articles/10.3389/fanim.2025.1635191 DOI=10.3389/fanim.2025.1635191 ISSN=2673-6225 ABSTRACT=Elucidating the gonadal development patterns of organisms holds significant reference value for advancing large-scale breeding and sustainable utilization of species. This study systematically investigated the annual population structure (test diameter-wet weight allometric model), gonadal histology (gametogenesis chronology), and environmental conditions of Tripneustes gratilla. The key findings include the following: 1. Test diameter (60.10–147.89 mm) exhibited a significant positive correlation with wet weight (R² = 73.54%), with both parameters peaking in May–June before declining sharply in September–October, indicating synchronized seasonal morphological changes. 2. Gonadal development displayed a bimodal pattern, with the gonad index (GI) reaching primary (8.26 ± 2.99) and secondary (7.30 ± 3.15) reproductive peaks in September and December, respectively. Compared with males, females presented significantly superior gonadal development during July–August (P < 0.05). 3. Water temperature dynamics were highly synchronized with GI fluctuations, where the July–September warming phase was strongly associated with reproductive peaks, confirming the temperature-driven physiological synchronization of reproductive cycles. These results demonstrate that T. gratilla employs dual survival strategies through seasonal adjustments in morphological-reproductive traits to adapt to environmental fluctuations, providing critical theoretical insights into the reproductive ecology of echinoderms.