Size bias in the documentation of marine biodiversity

Biodiversity exploration is incomplete, with a substantial gap between described and undiscovered species. Biases occur in these taxonomic descriptions, favoring easily observable and common species, leading to a skewed representation of ecological diversity, particularly in marine environments where deep‐sea life and smaller invertebrate groups remain underexplored. Here, we examine dynamics of taxonomic bias in describing marine biodiversity, emphasizing the relationship between the size of species and the timing of their formal description. Analyzing data from over 62 000 marine animal species across nine phyla, we find a significant inverse correlation: smaller species are consistently described more recently. This pattern persists across taxa and habitats, with fluctuations observed over time, including notable inflections coinciding with historical events and technological advancements. These results underscore the implications of taxonomic bias for ecological understanding and conservation efforts, emphasizing the importance of completing inventories of marine life, particularly focusing on small‐bodied, potentially threatened species.