First Completely Warm-blooded Fish Discovered

Opah (Courtesy of NOAA)

Opah (Courtesy of NOAA)

The discovery of the first wholly warm-blooded fish has made a splash in headlines recently.  It is the opah, also known as a moonfish.  “New research at NOAA Fisheries has revealed the opah, or moonfish, as the first fully warm-blooded fish that circulates heated blood throughout its body much like mammals and birds, giving it a competitive advantage in the cold ocean depths” (NOAA, 2015).

It was previously thought that the fish was a slow moving type, as most fish are at the depths at which this fish lives.  It is found in cold depths from 150 to 1,300 feet below the ocean surface.  It is silvery and its size about the size of an automobile tire. (NOAA, 2015)

The opah uses its pectoral muscles and body fat to keep its blood heated throughout its body.  It is the only fish thus far discovered to be completely warm-blooded.  Other fish are known to keep certain portions of their bodies warm, such as tuna and some sharks.  For the opah, this warm blood has proven to be a predatory advantage. The higher body temperature is responsible for increased muscle performance, brain function and eye function, and the fatty tissue surrounding the fish’s heart and gills keeps the blood warm.

For more information:

Visit NOAA Fisheries


NOAA. (2015, May 12). NOAA Fisheries | Southwest Fisheries Science Center. Retrieved from

This entry was posted in Nature, Oceanography, Research, Science and tagged , , , , , , . Bookmark the permalink.

2 Responses to First Completely Warm-blooded Fish Discovered

  1. Alex Jones says:

    Nature never ceases to amaze.

    Liked by 1 person

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