Thermal Physiology of Fiddler Crabs

Fiddler crabs are intertidal ectotherms that inhabit thermally dynamic mudflat and mangrove environments. Their body temperature is a function of environmental heat exchange, behavioural adjustments and physiological thresholds. Key adaptations include the use of burrows as thermal refuges, bimodal respiration that allows switching between aerial and aquatic gas exchange, and adjustments in metabolic rate and haemolymph oxygen transport to maintain performance across fluctuating temperatures. Sexual dimorphism and life stage further modulate thermal sensitivity, with males and females often exhibiting distinct thermal tolerances linked to reproductive investment. At the cellular level, enzymes involved in energy metabolism show temperature‐dependent kinetics that underpin whole‐animal thermal limits. The integration of behavioural, organismal and biochemical responses defines the thermal niche of fiddler crabs and determines their capacity to cope with extreme heat, tidal cycles and ongoing climate warming.

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Thermal Physiology of Fiddler Crabs publication trend

The graph below shows the total number of articles in thermal physiology of fiddler crabs across all publications each year (not limited to Nature Index journals).

Technical terms

Critical thermal maximum: The highest temperature at which a crab maintains coordinated activity before onset of thermal incapacitation.

Burrow retreat: A behavioural thermoregulation strategy where crabs use cooler subterranean burrows to lower body temperature.

Bimodal respiration: Dual breathing mode allowing gas exchange in both water (via gills) and air (via branchiostegal lungs).

Thermal niche: The range of environmental temperatures within which an organism can survive, grow and reproduce.

Metabolic rate: The rate of energy expenditure, often measured as oxygen consumption, reflecting physiological performance under different temperatures.

References

1. Rising surface temperatures lead to more frequent and longer burrow retreats in males of the fiddler crab, Minuca pugnax. Journal of Thermal Biology (2023).
2. The trade-off between heat tolerance and metabolic cost drives the bimodal life strategy at the air-water interface. Scientific Reports (2016).
3. Living on the Edge: Physiological and Kinetic Trade-Offs Shape Thermal Tolerance in Intertidal Crabs From Tropical to Sub-Antarctic South America. Frontiers in Physiology (2020).
4. Temperature Extremes and Sex-Related Physiology, Not Environmental Variability, Are Key in Explaining Thermal Sensitivity of Bimodal-Breathing Intertidal Crabs. Frontiers in Marine Science (2022).
5. Reproducing on Time When Temperature Varies: Shifts in the Timing of Courtship by Fiddler Crabs. PLOS ONE (2014).