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Science news in brief: From fluorescent mammals to cannibal cockroach couples

Meet the newest member of the fluorescent mammal club

Platypuses do it. Opossums do it. Even three species of North American flying squirrel do it.

And, breaking news: two species of rabbit-size rodents called springhares do it. That is, they glow under black light, that perplexing quirk of certain mammals that is baffling biologists and delighting animal lovers all over the world.

Springhares, which hop around the savannahs of southern and eastern Africa, weren’t on anyone’s fluorescence bingo card.

Like the other glowing mammals, they are nocturnal. But unlike the other creatures, they are Old World placental mammals, an evolutionary group not previously represented. Their glow, a unique pinkish-orange the authors call “funky and vivid,” forms surprisingly variable patterns, generally concentrated on the head, legs, rear and tail.

Fluorescence is a material property rather than a biological one. Certain pigments can absorb ultraviolet light and re-emit it as a vibrant, visible colour.

But mammals, it seems, don’t tend to have these pigments. A group of researchers, many associated with Northland College in Ashland, Wisconsin, has been chasing down exceptions for the past few years – ever since one member, biologist Jonathan Martin, happened to wave a UV flashlight at a flying squirrel in his backyard. It glowed eraser pink.

The researchers then went to the Field Museum in Chicago. When the team tried a drawer that housed preserved springhares, they beamed back.

Over the next several years, the researchers examined 14 springhare specimens from four countries, some male and some female. All showed fluorescence – many in a patchy pattern, which was unique among mammals they’ve studied, Olson said.

Chemical analysis of springhare hair found that the fluorescence comes largely from a set of pigments called porphyrins, which have also been found to cause this effect in marine invertebrates and birds, said Michaela Carlson and Sharon Anthony, chemists at Northland College who worked on the paper.

But the biggest question is: why?

The springhare findings in particular provide some avenues for exploration. There is a possibility that fluorescence helps animals hide from predators with UV-sensitive vision, by absorbing wavelengths that would otherwise be brightly reflected and emitting less visible ones. In that case a patchy pattern like the springhares’ might be another asset, Olson said.

Conch shell from the Marsoulas Cave

Hear the sound of a seashell horn found in an ancient French cave

In 1931, researchers working in southern France unearthed a large seashell at the entrance to a cave. Unremarkable at first glance, it languished for decades in the collections of a nearby natural history museum.

Now, a team has reanalysed the roughly foot-long conch shell using modern imaging technology. It’s an extremely rare example of a “seashell horn” from the Paleolithic period, the team concluded. And it still works — a musician recently coaxed three notes from the 17,000-year-old shell.

“I needed a lot of air to maintain the sound,” said Jean-Michel Court, who performed the demonstration and is also a musicologist at the University of Toulouse.

The Marsoulas Cave, in the foothills of the French Pyrenees, has long fascinated researchers with its colourful paintings depicting bison, horses and humans. It’s where the enormous tan-coloured conch shell was first discovered, an incongruous object that must have been transported from the Atlantic Ocean, over 150 miles away.

Only in 2016 did researchers begin to analyse the shell anew. Artefacts like this conch help paint a picture of how cave dwellers lived, said Carole Fritz, an archaeologist at the University of Toulouse who has been studying the cave and its paintings for over 20 years.

Fritz and her colleagues started by assembling a three-dimensional digital model of the conch. They immediately noticed that some parts of its shell looked peculiar. For starters, a portion of its outer lip had been chipped away. That left behind a smooth edge, quite unlike Charonia lampas, said Gilles Tosello, a prehistorian and visual artist also at the University of Toulouse.

The apex of the conch was also broken off, the team found. Indeed, further analysis showed that the shell had been struck repeatedly – and precisely – near its apex.

The mystery deepened when the team used CT scans and a tiny medical camera to examine the inside of the conch. They found a hole, roughly half an inch in diameter, that ran inward from the broken apex and pierced the shell’s interior structure.

All of these modifications were intentional, the researchers believe. The smoothed outer lip would have made the conch easier to hold, and the broken apex and adjacent hole would have allowed a mouthpiece to be inserted into the shell. The result was a musical instrument, the team concluded in their study, which was published in Science Advances.

Sawfish are locally extinct in 55 of 90 countries where they were once found

Can these hedge trimmers with fins avoid a brush with extinction?

Sawfish look something like hedge trimmers with fins and can reach lengths of 17 feet. To Jasmin Graham, president and chief executive of Minorities in Shark Sciences, it’s sometimes hard to believe such weird fish exist.

The animals, which are a kind of ray, face a variety of threats around the world, including habitat loss and entanglement in fishing nets. A pair of recent studies, one led by Graham and colleagues in Florida, reveals glimmers of hope for the species in some parts of the world. But the research also highlights regions where the fish are vanishing and points to work that is needed to prevent them from disappearing from more places.

Helen Yan, a marine biodiversity and conservation researcher at Simon Fraser University in British Columbia, led the other new study, which was published in Science Advances. Her project was aimed at overcoming the difficulties of determining the true range of sawfish, which are rare and tend to live in shallow, murky waters.

The team of scientists she worked with amassed sawfish data from surveys of local fishing communities, ecological research, fisheries data, sightings, museum records and environmental DNA. Their modelling predicted that sawfish are locally extinct in 55 of 90 countries where they were once found.

The study expanded the list of countries where sawfish are extinct to include China, Iraq, Haiti, Japan, Timor-Leste, El Salvador, Taiwan, Djibouti and Brunei. It also identified eight nations where urgent action could make an outsized contribution to preserving them: Cuba, Tanzania, Colombia, Madagascar, Panama, Brazil, Mexico and Sri Lanka.

What emerged as key for healthy populations of all sawfish species, the study found, is availability of mangrove habitat combined with facing less pressure from fishing.

Yan’s international research was complemented by the American team Graham led. That study, published in January in Endangered Species Research, showed that the smalltooth sawfish’s stronghold within the United States is still mainly restricted to Florida, but it may be starting to expand. By tracking the fish with passive acoustic tags and an array of receivers, her team recently detected them as far north as Brunswick, Georgia.

Though international trade in sawfish and their parts is banned under the Convention on International Trade in Endangered Species of Flora and Fauna, intentional killing and by-catch still occurs. And countries have an imperfect record at enforcing prohibitions on trade in the fish’s fins and teeth.

Eating each others’ wings is of mutual benefit to newly mated cockroaches

Cannibalism may be key for these cockroach couples

For certain cockroaches living inside rotten logs in Asia, nothing says “I love you” like some minor cannibalism.

Newly mated pairs of one species, Salganea taiwanensis, take turns chewing each other’s wings down to stubs after they move into the homes where they will jointly raise babies. Scientists say this unique behaviour may have evolved because of the roaches’ truly monogamous bond.

Haruka Osaki, who published the finding in Ethology, first happened upon some wingless roaches in 2014. She had been collecting insects from the woods as a hobby since becoming a biology student at Kyushu University in Japan the previous year. “When I caught the wood-feeding cockroaches in the wild, I noticed that their wings were chewed by something,” Osaki said.

When it was time to choose a topic for her doctoral research a couple of years later, Osaki thought of the roaches. She knew from others’ observations that the damage probably didn’t come from predators, but from cockroaches eating each other’s wings. But she didn’t know why. Her adviser, Eiiti Kasuya, encouraged her to dive in.

After some of her young, wild-caught cockroaches matured into adults, Osaki paired them off in the lab, creating 24 couples. Then she recorded their behaviour with video cameras for three days.

The videos revealed that the roaches ate each other’s wings in stages.

Twelve of the couples ate each other’s wings completely.

Wood-eating cockroaches aren’t the only creatures that make a meal out of their mates, but their motivations may be unique.

“Cannibalism is quite frequent in spiders,” said María José Albo, an evolutionary biologist at the University of the Republic in Uruguay. Among sexually cannibalistic spiders and insects such as praying mantises, it’s usually a larger female who eats her mate.

All of these cases involve only one mate being fed, Albo said, which makes the cockroaches so unusual. “If the mutual wing-eating has fitness benefits for both sexes, it will be the first case of mutual gift-feeding,” she said.

Those benefits probably aren’t nutritional, Osaki and Kasuya wrote, because the cockroach wings aren’t fleshy. But the roaches probably do benefit from losing their wings, because wings are cumbersome when living in tight quarters. Wings can also collect mould or mites, the authors wrote.

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