Temperature sensing in fishes: mechanisms and modulation in a warming world

Climate change is threatening global biodiversity as a result of increasing temperature and climate variability outpacing adaptation rates. Ectothermic animals, such as most fishes, are particularly vulnerable to environmental change because their physiology is intimately controlled by their surrounding environment. Importantly, the impact of temperature on animals depends not only on the degree of warming but also on their ability to accurately detect and evade that warming. The first step in this process is the recognition of changes in temperature by integral membrane proteins such as transient receptor potential (TRP) channels, some of which are temperature sensitive (thermoTRPs). Most of our understanding of thermoTRPs comes from studies in mammals, with a dearth of information in ectotherms on thermal sensitivities, and modulation of these thermal sensors. In this Commentary, we highlight what is known about the mechanism of temperature sensing in fishes. We also propose that changes in biological context (e.g. social interactions, lipids and immune state), leading to changes in physiology and behaviour, influence how fish sense temperature, potentially altering thermal susceptibility. Finally, we discuss redundancy in temperature-sensing systems, identify knowledge gaps, and suggest integrative approaches and questions for us to better understand temperature sensing and its modulation in fishes.