Disney’s Cinderella is not the only place you can hear mice “sing.” Some real-world rodents also serenade each other. And now, scientists know how. The mice inflate tiny, balloon-like sacs in their airways. This creates whistling tunes.

Making music this way may be unique in the animal kingdom.

The critters are known as Alston’s singing mice. Found in the forests of Mexico and Central America, they truly live up to their name. Both males and females communicate with trains of high-pitched notes. Remarkably, their songs are more complex than those of any other rodent.

In just a 10-second song, an Alston’s singing mouse belts out around 100 individual breaths and notes. The melody attracts mates and warns rival males to stay away, says Samantha Smith. The song’s speed and length make it far more “extreme” than other rodents’ calls, she adds. Smith is a biologist at the University of Lausanne. That’s in Switzerland.

Smith is part of a team that wanted to know how the vocal systems of Alston’s singing mice evolved to create melodies. They started by dissecting the larynges of deceased animals. This “voice box” is a part of their bodies that helps mice (and us) breathe, swallow and make sound.

The researchers hooked each excised mouse voice box to a tube. Then, they pointed a microphone and camera toward its top. “A [voice box] is basically just a tube with a valve in it that can open and close,” explains Smith. To see how the voice box moved and produced sound, the team blew air through the tube.

Sometimes, the voice box produced sounds that ranged in the mouse’s natural pitch. But this happened only when a pouch on the inside of the voice box was inflated. When the researchers blocked this balloon with bits of wax or small metal balls, the voice box went silent. Cutting the sac had the same effect. The air sac, it seemed, is key to making the songs.

Other rodents have air sacs, but they don’t appear to use them to sing.

Smith and her teammates shared their findings May 6 in Proceedings of the Royal Society B.

A unique musical talent

Raffaela Lesch is impressed by the team’s experiment and its choice of species. She works at the University of Arkansas at Little Rock. As a bioacoustician, she studies how animals use sound to communicate.

“Working with [voice boxes] this small is not an easy task,” she says. But for Lesch, learning more about how rodents produce sound is exciting. They’re “such a diverse group with such fascinating social, behavioral and ecological adaptions,” she says. 

It’s not yet clear how the sac generates its whistle. The sound could come from air vibrating at the sac’s entrance. That would be similar to the way opening a car’s sunroof can make noise as air rushes past the opening.

Another possibility is a bit like how flutes and organ pipes work. A sharp cartilage rim at the sac’s entrance may be deflecting air, producing the tone.

Inflatable sacs in airways have evolved multiple times. Primates, birds, reptiles, frogs and other animals have them. But in those cases, air sacs alter or amplify sound produced elsewhere in the respiratory tract. (That’s the system of organs that are involved in breathing.) The songs of the singing mice, on the other hand, are made by the sacs themselves.

“Our study expands our understanding of the ways in which [air sacs] can shape vocal communication,” Smith says. Studying different features of rodent air sacs may help reveal how these songs first evolved — no Disney magic needed.

The kraken — a giant, tentacled sea monster that dragged ships into the depths — is a creature of Norwegian myth. But millions of years ago, a similar, real-life animal roamed the oceans, a new study finds.

The new analysis of jaw fossils suggests that as dinosaurs ruled the land, whale-sized octopuses ruled the seas. These super-sized cephalopods would have been the largest marine animals of the Late Cretaceous Period. That’s from about 66 million to 100 million years ago.

Researchers reported their findings April 23 in Science.

It’s difficult to study fossil octopuses, notes Yasuhiro Iba. He’s a paleontologist at Hokkaido University. That’s in Sapporo, Japan. With soft bodies, these animals tend to break down before becoming fossils. Very few hard parts remain to fossilize. Fortunately, both ancient and modern-day octopuses have a hard, beak-like jaw. This structure is made of chitin (KY-tin). This material is strong enough to survive the animal’s death and fossilize.

The jaws appeared to come from an octopus-like creature. But until now, details of the body size and animal’s role in the ocean ecosystem had been a mystery, Iba says.

A fresh look at old fossils

To find those details, Iba was part of a team that examined 15 fossil jaws. Found in Japan and Canada’s Vancouver Island, they date to near the end of the age of dinosaurs.

Iba’s team took careful measurements. They also compared the mystery jaws to those from other species of octopus and squid. The team also found 12 jaw fossils embedded in rocks in Japan. Some were too fragile to dig out. So they examined them with a technique called digital fossil mining. It records fossils as detailed 3-D digital images.

To make these images, they ground down the rocks layer by layer. Each layer exposed a new bit of the fossils. The researchers then took photographs of each layer. Afterward, the team used these images — with some help from artificial intelligence — to make digital models of the fossils.

Researchers once thought these 27 cephalopods belonged to five extinct species. But as Iba and his colleagues learned more about them, they divided them into just two. There was Nanaimoteuthis jeletzkyi (Nuh-NY-moh-TOOTH-is Jeh-LETZ-skee-eye) and the much larger N. haggarti. The new analyses suggest the behemoths were early finned octopuses.

This group of deep-sea animals has webbing between their arms and flapping fins on the other end of their body. Finned octopuses still exist. One example is the dumbo octopus. The ancient ones were much, much larger.

The largest lower jaw from an N. haggarti was big enough to hold a grapefruit. It also was about 50 percent bigger than that of the modern giant squid. At 12 meters (39 feet) long, that squid is one of the largest cephalopods alive today.

Iba estimates that N. haggarti could have spanned seven to 19 meters (23 to 63 feet) from its head to the tips of its arms. That’s between the length of an ambulance and a school bus.

The animal “may have been among the largest invertebrates in Earth’s history,” Iba now concludes.

No bones about it

N. haggarti appears to have been bigger than even the largest ocean predators of its time. These would have included huge reptiles, such as mosasaurs and long-necked plesiosaurs.

Clues in the fossil jaws suggest the ancient giant octopuses competed with those top predators for a spot in the food chain. The researchers found wear and damage to the animals’ jaws. These scrapes and scuffs suggest the octopuses had been powerful predators. Biting on shells and bones likely roughed up their jaws.

That discovery seems to shed new light on ancient marine ecosystems. It suggests that a wider range of predators roamed the ancient seas than once thought.

“For a long time, the top of the marine food web has been thought to be dominated by large vertebrates,” Iba says. By mosasaurs and plesiosaurs, for example. “Our study shows that giant invertebrates — octopuses — also occupied that role in the Cretaceous,” he says.

It’s possible that Nanaimoteuthis was a bit smaller, notes Christian Klug. He’s a paleontologist at the University of Zurich, in Switzerland. The fossil remains are incomplete, he notes. Iba’s team used only the jaw fossils as it estimated total-body length.

Still, he says, “there is no doubt that these animals ranged among the top predators.” Future findings, he adds, may help pinpoint their roles in those ancient seas.

Paleontologist Adiël Klompmaker works at the University of Alabama in Tuscaloosa. He hopes some giant octopus fossils will turn up with well-preserved stomach contents. “That would tell us what they ate,” he says. Were they hunting shelled invertebrates, such as large ammonites? “Or did they also go after large vertebrates?”

Only time and more work by paleontologists will reveal such “kraken” secrets.