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Poulsen et al. 2016. PLOS One.
Poulsen et al. 2016. PLOS One.

Unique Glow Helps Identify Two New Fish Species

Poulsen et al. 2016. PLOS One.
Poulsen et al. 2016. PLOS One.

Scientists have found two new species of glowing fish with tube-shaped eyes and mirrors on their bellies, according to their research in journal PLOS One.

The Opisthoproctidae, or barreleyes, are a unusual family. For example, take a look at the transparent-headed, tiny-mouthed Macropinna microstoma. Those green objects pointing upward are its eyes, and what appear to be eyes at front are actually the barreleye equivalent of nostrils. 

Scientists have had a hard time getting to know the barreleyes better because the fishes’ delicate bodies kind of collapse once they’re out of the water. M. microstoma, for example, was first described in 1939, but nobody knew about its clear, fragile forehead until a remotely operated vehicle captured the video above in 2004.

Based on the evidence they had, researchers believed there were 19 species in the barreleye family. Some of these species have bioluminescent, or light-producing, organs in their bellies, along with mirror-like organs called soles that lie beneath the glow, controlling and directing its light.

During a research cruise in 2013 and 2014, the Japanese research vessel Hakuho-Maru pulled up four fish that looked like barreleyes. Researchers onboard the boat took tissue samples, then dropped the fish into ethanol and stored them in a sub-zero freezer to help the specimens keep their shape.

An international team of scientists took it from there. They examined and photographed the specimens and sequenced their DNA, then compared these results with data on existing barreleye species. They found that, while similar to one another, the new fishes’ mirror bellies showed three different types of markings. The DNA tests confirmed it: They were three different species, two of which had never been seen before. The new species were definitely barreleyes, but were so distinct from known species that the researchers put them in a separate genus, Monacoa. (They suggest calling them "long-nosed mirrorbellies" in the vernacular.)

Monacoa is what’s called a resurrected genus. A long time ago, ichthyologist GP Whitley believed he’d found a fish different enough from its kin to merit a new genus, which he named Monacoa. Later, other scientists disagreed, and moved Monacoa grimaldii into the genus Opisthoproctus. But based on the markings on the new fishes’ bellies, the authors of the current study say Whitley was right. They realized that the old specimens could never have led to this conclusion, as the formalin used to preserve the fish damaged their markings.

The two new species, M. niger and M. griseus, are both native to the Pacific Ocean. Unlike other fish that prefer pure blackness, these fish inhabit depths that still get some sunlight. In semi-lit conditions, the authors say, the barreleyes might use their bioluminescence as camouflage, or to communicate with one another. 

"This new study on the deep-sea has shown unknown biodiversity in a group of fishes previously considered teratological variations of other species," lead author Jan Poulsen of the Australian Museum said in a press statement. "The different species of mirrorbelly-tube eyes can only be distinguished on pigmentation patterns that also constitutes a newly discovered communication system in deep-sea fishes."

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Big Questions
What's the Difference Between Gophers and Groundhogs?
Gopher or groundhog? (If you chose gopher, you're correct.)
Gopher or groundhog? (If you chose gopher, you're correct.)
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Gophers and groundhogs. Groundhogs and gophers. They're both deceptively cuddly woodland rodents that scurry through underground tunnels and chow down on plants. But whether you're a nature nerd, a Golden Gophers football fan, or planning a pre-spring trip to Punxsutawney, Pennsylvania, you might want to know the difference between groundhogs and gophers.

Despite their similar appearances and burrowing habits, groundhogs and gophers don't have a whole lot in common—they don't even belong to the same family. For example, gophers belong to the family Geomyidae, a group that includes pocket gophers (sometimes referred to as "true" gophers), kangaroo rats, and pocket mice.

Groundhogs, meanwhile, are members of the Sciuridae (meaning shadow-tail) family and belong to the genus Marmota. Marmots are diurnal ground squirrels, Daniel Blumstein, a UCLA biologist and marmot expert, tells Mental Floss. "There are 15 species of marmot, and groundhogs are one of them," he explains.

Science aside, there are plenty of other visible differences between the two animals. Gophers, for example, have hairless tails, protruding yellow or brownish teeth, and fur-lined cheek pockets for storing food—all traits that make them different from groundhogs. The feet of gophers are often pink, while groundhogs have brown or black feet. And while the tiny gopher tends to weigh around two or so pounds, groundhogs can grow to around 13 pounds.

While both types of rodent eat mostly vegetation, gophers prefer roots and tubers (much to the dismay of gardeners trying to plant new specimens), while groundhogs like vegetation and fruits. This means that the former animals rarely emerge from their burrows, while the latter are more commonly seen out and about.

Groundhogs "have burrows underground they use for safety, and they hibernate in their burrows," Blumstein says. "They're active during the day above ground, eating a variety of plants and running back to their burrows to safety. If it's too hot, they'll go back into their burrow. If the weather gets crappy, they'll go back into their burrow during the day as well."

But that doesn't necessarily mean that gophers are the more reclusive of the two, as groundhogs famously hibernate during the winter. Gophers, on the other hand, remain active—and wreck lawns—year-round.

"What's really interesting is if you go to a place where there's gophers, in the spring, what you'll see are what is called eskers," or winding mounds of soil, Blumstein says [PDF]. "Basically, they dig all winter long through the earth, but then they tunnel through snow, and they leave dirt in these snow tunnels."

If all this rodent talk has you now thinking about woodchucks and other woodland creatures, know that groundhogs have plenty of nicknames, including "whistle-pig" and "woodchuck," while the only nicknames for gophers appear to be bitter monikers coined by Wisconsin Badgers fans.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Animals
Watch Christmas Island’s Annual Crab Migration on Google Street View
Google
Google

Every year, the 45 million or so red crabs on the remote Australian territory of Christmas Island migrate en masse from their forest burrows down to the ocean to mate, and so the female crabs can release their eggs into the sea to hatch. The migration starts during the fall, and the number of crabs on the beach often peaks in December. This year, you don’t have to be on Christmas Island to witness the spectacular crustacean event, as New Atlas reports. You can see it on Google Street View.

Watching the sheer density of crabs scuttling across roads, boardwalks, and beaches is a rare visual treat. According to the Google blog, this year’s crabtacular finale is forecasted for December 16, and Parks Australia crab expert Alasdair Grigg will be there with the Street View Trekker to capture it. That is likely to be the day when crab populations on the beaches will be at their peak, giving you the best view of the action.

Crabs scuttle across the forest floor while a man with a Google Street View Trekker walks behind them.
Google

Google Street View is already a repository for a number of armchair travel experiences. You can digitally explore remote locations in Antarctica, recreations of ancient cities, and even the International Space Station. You can essentially see the whole world without ever logging off your computer.

Sadly, because Street View isn’t live, you won’t be able to see the migration as it happens. The image collection won’t be available until sometime in early 2018. But it’ll be worth the wait, we promise. For a sneak preview, watch Parks Australia’s video of the 2012 event here.

[h/t New Atlas]

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