It’s weird animal Friday again and, while these animals don’t have multiple mouths or human faces, one is a world’s first and another is a world record breaker. The world’s first is the world’s first warm-blooded fish. And just in case you’re wondering, there’s actually a cold-blooded mammal or two. Topping things off, a world-record eel caught off the coast of England is definitely the biggest but its length may be a fish tale.

According to the journal Science, new research by the NOAA (National Oceanic and Atmospheric Administration) Fisheries has determined that the deep sea fish called the opah or moonfish (Lampris guttatus) is the world’s first warm-blooded fish. It’s all in the gills as the opah is the only fish with blood vessels in its gills that warm the blood circulating through its body. As a result, it has a faster metabolism that most deep sea fish, increasing its speed and reaction time to make it a dangerous predator.

Are there any cold-blooded mammals? Sort of. The East African naked mole-rat (Heterocephalus glaber) is the world’s only thermoregulating mammal, meaning that it uses its surroundings to regulate its body temperature rather than an internal mechanism, like the way humans sweat to cool off or get goose bumps to warm up. An extinct miniature goat (Myotragus balearicus) that lived on what is now the Spanish island of Majorca, was also cold-blooded and managed to survive for millions of years until humans showed up on the island 3,000 years ago and killed them off.

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Naked mole-rats

Eels are cold-blooded and the Conger eel caught off Plymouth in Devon, England, this week was a cold-blooded monster weighing in at 160 pounds (72.5kg), breaking the old record of 133 pounds. The picture tweeted by the proud fishermen who hauled it in showed the eel to be 21 feet long but that fish tale was reduced to 7-10 feet when it was pointed out that eels stretch considerably when hung up for weighing. That’s still one big Conger.

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World record Conger eel

Warm-blooded fish, cold-blooded rats and monster eels. We share the universe with a lot of mysterious creatures, don’t we?

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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