An Osaka Metropolitan University-led team has demonstrated that bluestreak cleaner wrasse (Labroides dimidiatus) check their body size in a mirror before choosing whether to attack fish that are slightly larger or smaller than themselves.

The study, published in Scientific Reports, suggests that bluestreak cleaner wrasse possess some mental states (e.g., mental body image, standards, intentions, goals), that are elements of private self-awareness.

The team of OMU Graduate School of Science student Taiga Kobayashi, Specially Appointed Professor Masanori Kohda, Professor Satoshi Awata, and Specially Appointed Researcher Shumpei Sogawa, and Professor Redouan Bshary of Switzerland’s University of Neuchâtel, were among the group that last year reported the cleaner wrasse could identify photographs of itself as itself, based on its face through mirror self-recognition.

This time, the cleaner wrasse’s behavior of going to look in the mirror installed in a tank when necessary indicated the possibility that the fish were using the mirror to check their own body size against that of other fish and predict the outcome of fights.

“The results that fish can use the mirror as a tool can help clarify the similarities between human and non-human animal self-awareness and provide important clues to elucidate how self-awareness has evolved,” doctoral candidate Kobayashi said.

Shinkansen bullet trains could be whizzing around Japan without drivers from the mid 2030s, one of its main rail operators said, motivated in part by the country’s demographic crisis.

East Japan Railway (JR East) will first introduce trains where many of the driver’s tasks are automated—but they will remain in the cab—on parts of one route from 2028, the firm said Tuesday.

The following year, the company hopes to trial driverless trains on a short stretch of out-of-service track before rolling them out between Tokyo and Niigata on the Joetsu Shinkansen line in the mid 2030s.

“Through realizing driverless driving and transforming railway management to an efficient and sustainable system, we will adapt to changes in the social environment such as declining population and reforms in ways of how workers work,” a company statement said.

The main drive behind the plan, however, “is the need to constantly innovate railway technology, and that could in turn help address labor shortage and other issues”, a JR East spokesman told AFP on Wednesday.

The Shinkansen’s maximum speed on the Joetsu route is 275 kilometers (170 miles) per hour, but on other lines they can run at 300 km/h or faster.

Japan, whose shrinking population is the world’s second oldest, is already facing worker shortages across many sectors of the economy.

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In 2003, a team of primatologists led by the University of Colorado Boulder trapped, tagged and released a male ring-tailed lemur in the Bezà Mahafaly Special Reserve in Madagascar. The researchers captured him one more time in 2004, but after that, the lemur disappeared, never to be seen again.

That is, until 2008 when his internally placed electronic tag, similar to a dog’s microchip, showed up in a pile of scat from a forest cat. This predator is related to domestic cats and was likely introduced to the island off the coast of Africa hundreds of years ago.

Now, that case of cat predation is part of a new study exploring how such attacks could endanger the conservation of lemurs. Over the course of 14 months, researchers from the United States and Madagascar became lemur crime scene investigators. They gathered a wide range of data, including camera trap photos, scat samples and eye-witness reports to unravel the mystery of who is eating these primates at Bezà Mahafaly.

Their findings suggest that predators not native to Madagascar, such as forest cats and dogs, may kill more lemurs than scientists once believed. Lemurs live only in Madagascar, and several species are already in danger of going extinct.

“It’s not that people didn’t know that predation was happening,” said Michelle Sauther, lead author of the new study and a professor of anthropology at CU Boulder. “But they’ve mostly been looking at other conservation priorities like the effects of deforestation.”

She and her colleagues published their findings in the journal Folia Primatologica.

The study focused on Bezà Mahafaly, a roughly 242-acre protected area at the southwestern tip of Madagascar. Here, tamarind trees grow along river drainages, turning a lush green during the rainy season from October to March.

The reserve is home to four species of lemurs: the ring-railed lemur (Lemur catta) and Verreaux’s sifaka (Propithecus verreauxi), which are out during the day; the white-footed sportive lemur (Lepilemur leucopus) and the gray-brown mouse lemur (Microcebus griseorufus) are awake at night. Of those, all but the mouse lemur are considered endangered or critically endangered.

Sauther, who has been studying lemurs in Bezà Mahafaly since the late 1980s, sees the research as an example of what scientists can discover when they really get to know a natural area.

“When you’re doing a long-term study and you come back year after year, you find out things are not always the way you think they are,” she said.

Scat detectives

Lemurs have several natural predators. They include the fosa (Cryptoprocta ferox), a strange mammal that is related to the mongoose but is much bigger and looks a bit like a puma. Before this study, researchers thought that the fosa had been extirpated from the area.

In 2008, Sauther and her colleagues noticed that something seemed to be amiss in the reserve. One day, they heard a troop of ring-tailed lemurs screaming and found a recently killed lemur on the forest floor.

“That year, we were walking through the forest looking for lemurs, and we kept finding dead guys,” she said. “We thought: “Something’s going on.'”

Her team, including Frank Cuozzo, who earned his doctorate in biological anthropology from CU Boulder in 2000, decided to investigate. The study was a massive operation: From June 2008 to July 2009, the group set up cameras at nine locations throughout the reserve. Researchers walked for miles along trails every week to search for scat and lemur predation. They then sifted through those droppings to look for bones or other evidence of predation.

In all, the team collected 13 examples of predator attacks on lemurs, including the case of the ring-tailed lemur whose electronic tag showed up in cat scat. At least six of those primates were probably killed by dogs or cats. Another five may have been the victims of either cats or fosa, which leave behind similar tooth marks.

The team concluded that a combination of fosa, forest cat and dog predation can lead to potentially dangerous spikes in lemur deaths.

“That’s when we really started thinking: Wow, there’s a lot of predation here from endemic animals like the fosa, but also the introduced animals like dogs and forest cats,” said Cuozzo, now affiliated with the Lajuma Research Center and the Mammal Research Institute at the University of Pretoria in South Africa.

Predator spectrum

Sauther noted that cats and dogs may be so effective at preying on lemurs because the primates haven’t had much time to evolve defenses against these new arrivals.

In a previous study, she and her colleagues used DNA evidence to show that Madagascar’s forest cats are descended from domestic cats from the Arabian Sea region—and likely came to the island aboard merchant ships.

She and Cuozzo can’t be sure how much of a dent these predators are making in lemur numbers. But they suspect that it’s more than scientists have previously accounted for. Across Madagascar, populations of most lemur species are continuing to decline today.

The researchers urge scientific funding groups to support more long-term research projects that can unravel the full spectrum of threats facing endangered species.

“Predation is a dynamic process,” Sauther said. “You can’t just say, ‘Cats are doing this, and dogs are doing that.’ You really have to look at what the whole predator group is doing.”