The “Opah” (Or Moonfish) Is The World’s Only Warm-Blooded Fish, Maintaining Body Heat 5°C Higher Than Its Environment
IFLScience••science
Key Points:
- Moonfish have been discovered to maintain a body temperature about 5°C (9°F) warmer than the surrounding cold ocean water, making them fully endothermic, unlike typical cold-blooded fish.
- Scientists found a unique counter-current heat exchange system in the moonfish’s gills, where warm blood leaving the body heats the cold blood returning from the gills, preventing heat loss during oxygen exchange.
- This adaptation allows moonfish to swim faster, see better, and be more active predators, giving them a competitive edge in their deep-sea environment.
- The discovery marks the first known instance of a fish being fully warm-blooded, as previous examples only showed partial heat generation linked to movement.
- Research
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