A Rare Deep-Sea Shapeshifting Whalefish Was Spotted For Just The 18th Time In 34 Years

Monterey Bay shapeshifting whalefish spotted

iStockphoto / Serbek

  • The Whalefish (Whalefish, Cetomimus sp.) is so rare that it has only been spotted 18 times in the past 34 years
  • This shapeshifting fish can take on three distinct forms throughout its life which which confused scientists for years, completely unaware the males and females were the same species
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The Whalefish is kind of a funny name for this species that’s actually incredibly small. It’s almost like naming an obese mobster ‘tiny’ except this name comes because of the shape of the body resembling a whale.

On a recent deep-sea exploration expedition in Monterey Bay, the Monterey Bay Aquarium Research Institute (MBARI) spotted one of these incredibly elusive whalefish. It is only the eighteenth time in the past thirty-four years that one of these fish has been observed.

One of the characteristics that make the Whalefish so remarkable is how it can take on three distinct forms. It’s considered a shapeshifter. And the males and females look so different that it took scientists years to realize they were even the same species.

They all start out as “a scaleless larval form with a long, streamer-like tail” but then shift drastically. The males grow into a bignose with a very tiny mouth and the females develop this extravagant bright orange color you’ll see below. This specimen was spotted during the R/V Western Flyer expedition at 2,013 meters (6,604 feet) deep off of Monterey Bay:

Someone on Twitter asked how a 10cm fish can be called a ‘whalefish’ and someone gave a really good explanation of that here:

Here’s a closer look at this fish. You can kind of get a much better sense of how small the whalefish is based on this video.

Something I never knew until today is just how deep the Monterey Bay Canyon is. The MBARI.org website has a great article comparing it to the Grand Canyon. Essentially, if you put them side by side the Monterey Bay Canyon is just 430-feet shallower than the deepest part of the Grand Canyon. You can click this image below to read that article if you want:


I was blown away when I read this whalefish was filmed at 6,600 feet because I had no idea that Monterey Bay was even a fraction of that deep. For context, the deepest portion of San Francisco Bay is 375-feet deep.