Navigating uncertainty in maximum body size in marine metazoans

Area of Science:

• Marine Biology
• Ecology
• Evolutionary Biology

Background:

• Body size is a critical trait influencing marine community structure and dynamics.
• Inconsistent measurement methodologies lead to significant discrepancies in species' maximum body size data.
• These variations can compromise the reliability of ecological and evolutionary studies.

Purpose of the Study:

• To analyze variations in reported maximum body sizes for marine metazoans.
• To investigate factors contributing to size discrepancies, including organism size, taxonomy, and habitat.
• To assess the implications of size variation on macroecological and macroevolutionary research.

Main Methods:

• Compiled and analyzed 69,570 maximum size measurements for 27,271 marine metazoan species.
• Examined relationships between size variation and organism size, taxonomy, habitat, and skeletal structures.
• Quantified within-species size variation and compared it to interspecific variation.

Main Results:

• 38% of species showed no variation in reported maximum size; most had low variation.
• Variation increased with species size and decreased with more measurements, with notable phyla/habitat differences.
• Pelagic organisms had low size range; small species with unspecified habitats showed highest variation.
• Within-species variation was smaller than interspecific variation.

Conclusions:

• Significant variation exists in marine species' maximum size estimates, influenced by size, taxonomy, and habitat.
• Standardized measurement protocols and improved metadata are recommended to reduce variation.
• Despite variations, published maximum size errors are rare and unlikely to significantly impact broad-scale research.