Scientists solve mystery: 3 fish are all the same

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This undated composite image provided by the Biology Letters of the Royal Society shows, from top, tapetail postlarval stage of cetomimid whalefish off Cozumel, Mexico; adult male of cetomimid whalefish from the Gulf of Mexico; and juvenile female of cetomimid whalefish from the eastern North Pacific. Researchers believe they have solved the puzzle of three seemingly different fish, one all males, one all females and on all juveniles. They are the same fish, an undergo remarkable changes as they mature. (AP Photo/Biology Letters of the Royal Society) Top image: Photo/Donald Hughes Middle image: Photo/G. David Johnson Bottom image: Monterey Bay Aquarium Research Institute,Bruce Robison

(AP) -- Researchers believe they have solved the puzzle of three seemingly different fish, one all males, one all females and one all juveniles. They're the same fish, and undergo remarkable changes as they mature. "You can imagine it was a pretty exciting discovery," said G. David Johnson, an ichthyologist at the Smithsonian's National Museum of Natural History. "The pieces kept falling into place."