A Comprehensive Repository of Morphological, Life‐History, Ecological, and Environmental Data for Sirenians and Marine Carnivorans Worldwide

Sirenians and marine carnivorans represent unique mammalian lineages that have transitioned from terrestrial to aquatic life. Although they serve as vital indicators of marine ecosystem health, nearly half of these species are threatened with extinction. However, a comprehensive database capturing both their biological traits and environmental variables has been lacking. To address this gap, we constructed a standardized data repository for all 46 species, integrating 56 variables across morphological and physiological, life‐history, ecological, biogeographical, environmental, and conservation dimensions. Additionally, we collected data on body size, coloration, distributional range, and extinction risk for all 22 subspecies. At the species level, environmental variables were nearly fully quantified, while trait completeness varied across other categories, ranging from 46.34%–100.00% for morphology and 20.00%–100.00% for life history. Using this repository, our phylogenetic models revealed that research effort was heavily biased, with migratory species and those described earlier possessing much higher data completeness. Furthermore, geographic range size emerged as the primary predictor of extinction risk. These findings highlight the urgent need to prioritize research and conservation efforts for these species, particularly those with restricted ranges or recent descriptions. Taken together, our integrated dataset fills historical knowledge gaps and provides a robust empirical foundation for guiding targeted, spatially explicit conservation actions for these vulnerable marine mammals.