Monkeys living on an island have learned to use a startling variety of tools and techniques to obtain the juicy innards of different foods – and to floss their teeth afterwards.

The Nicobar long-tailed macaque () is only found on three islands in the eastern Indian Ocean. One of them is Great Nicobar Island.

To find out about the macaques’ eating habits, at the Sálim Ali Centre for Ornithology and Natural History in Coimbatore, India, and colleagues followed 20 around a small coastal village on the island.

Will use anything

Many of the macaques’ favoured foods are thorny, slimy, hairy or mucky. To get rid of these inedible coatings, the macaques either wash the foods in puddles or wrap them in leaves and rub them clean. They also wrap leaves around certain foods to make them easier to hold. Trash like paper, cloth or plastic is also used for wrapping and wiping foods.

The macaques eat coconuts too, plucking them from the tree by twisting them around or using their teeth to cut them off. If it is tender, the macaques de-husk the coconut using their teeth, holding it down with their feet and hands, in order to get to the water and juicy bits inside.

If the coconut is ripe, however, they also have to crack its shell. To do so, they take it to a hard surface like a rock or concrete, and pound it.

It’s not just tool use. The macaques were seen beating bushes with their hands to disturb insects hiding within, catching those that fly out or drop to the ground.

Clean those teeth

After eating, adult and sub-adult macaques clean their teeth – they were seen holding a fine fibre between their teeth and pulling at it.

The macaques used a range of materials as dental floss: a tree needle, a bird feather, a blade of grass, a coconut fibre, a nylon thread and a metal wire. Some modify the threads before use, for instance by tearing them apart.

Nine of the 20 macaques were seen “flossing”. They did so after eating various foods in different habitats, says Kumara.

The Nicobar long-tailed macaques are the third monkeys seen flossing their teeth. use , while Thailand’s use .

Handy monkeys

“Wrapping irritating items, cleaning by rubbing, and flossing teeth with thin fibres have been described in other populations of macaques,” says primatologist at the University of Georgia, Athens. “The newest element, to me, is ‘bush-beating’ to flush insect prey.”

Macaques adapt well to human-dominated landscapes, where they tend to manipulate objects more, says primatologist at the Nanyang Technological University, Singapore. “They are the king of generalists
 about as adaptable as we are.”

Tool use on its own doesn’t take much intelligence, says Gumert. “However, the modification of tools does show planning and foresight – something that someone who has ever observed macaques in any detail would never have doubted.”

Take what you want

The fossil of an extinct salamander is so exquisitely preserved that the remains of its last meal – a frog – can be seen in its gut.

The fossil comes from the site of the Quercy phosphorites in south-west France, which has thrown up many vertebrate fossils over the years. This is despite a large number of specimens probably being destroyed by phosphate mining in the 19th and 20th centuries.

The salamander fossil had remained largely forgotten in the French National Museum of Natural History for decades, until of the JURASSICA Museum in Porrentruy, Switzerland, and his colleagues took a closer look.

They scanned the fossil using advanced imaging techniques, and named it after the phosphorus-rich sediments of Quercy. It is the only known fossil of this species, with a search in museums and sediment deposits coming up empty.

The salamander died 34 to 40 million years ago, yet aside from its skeleton, many of its soft tissues are preserved: an initial examination identified skin and a lung. These were protected by a process called permineralisation, sometimes loosely known as “mummification”. Under this mechanism, minerals from groundwater seep into a buried animal and fill any empty pockets, or even individual cells.

This type of soft tissue preservation is rare, says at the University of Manchester, UK.

Frog-muncher

When Tissier and his colleagues revisited the scan, they spotted other tissues, including digestive tract, nerves, muscles and an unidentified organ. But the “big surprise” came when they examined the digestive tract and found frog bones inside.

Those bones comprised four vertebrae and a 5-millimetre-long limb bone. “It was clear that they didn’t belong to the salamander, becauseÌęthey were in the wrong position andÌętoo small,” Tissier says. He isn’t sure whether the frog bones all belong to the same individual, but they do not come from any fully developed adults.

Regardless, the finding makes P. sigei the only extinct salamander known to have consumed frogs. “We definitely didn’t expect frog bones,” says Tissier, because modern salamanders rarely eat those animals.

“The frog was really small, which may have made it easier for the salamander to catch it,” he adds. The prey was just 18-20 millimetres long, whereas the salamander may have been 150 mm – although the fossil is only about 60mm long because it is missing its head and parts of its tail and neck.

Most present-day salamanders feed on invertebrates, with their mouths too small to consume large vertebrates, says herpetologist . “But if they can fit a vertebrate prey in their mouths, they typically will eat it.” The frog’s small relative size may have doomed it.

Journal reference: PeerJ, DOI:

Dramatic pose

Never mind the Leaning Tower of Pisa – this is the leaning tower of pines.

Cook pines are towering trees that were once restricted to their native home of New Caledonia, an archipelago in the Pacific Ocean. Through cultivation, they have taken root across tropical, subtropical and temperate regions around the world.

The trees often have slightly tilting trunks. żìĂš¶ÌÊÓÆ”s have now noted a bizarre pattern in their tilt: they lean south in their northern range and north in their southern range.

at California Polytechnic State University in San Luis Obispo was writing up a description of the Cook pine (Araucaria columnaris) for a when he realised that the pines always leaned south. So he rang up a colleague in Australia to see if that was the case there. It turned out it was – but this time the pines leaned north.

“We got holy-smoked that there’s possibly a tree that’s leaning toward the equator wherever it grows,” says Ritter.

He and his colleagues studied 256 Cook pines scattered across five continents. They collected tree data at 18 locations between latitudes of 7 and 35° north, and 12 and 42° south.ÌęThe team estimated that the trees tilt by 8.55 degrees on an average – about double the tilt of the Leaning Tower of Pisa.

The trees also slant more the further they are from the equator in both hemispheres. “It’s a shockingly distinct pattern,” says Ritter. One tree in South Australia slants at 40 degrees.

Drawn to the centre

Trees normally correct for such asymmetry in their growth, but for some unknown reason the Cook pine is unable to do so, says Ritter. “We could be just dealing with an artefact of its genetics that we are seeing now when we have spread it all over the world,” he says. Alternatively, it could be an adaptation to catch more sunlight at higher latitudes.

“The tilting phenomenon is not unusual,” says of the US Forest Service in Utah. In 2016, he reported that the found in the US always points south, thus cutting the cost of transporting nutrients to its flowers. Some cacti lean towards the sun too, he says. However, “this is the first time I have heard of a tree doing this”, says Warren.

at Stanford UniversityÌęfinds the north-south leaning pattern “fascinating.” Some pines, he says, strictly grow upright, whereas others are pretty sloppy about it.

Journal reference:ÌęEcology, DOI:Ìę

Doomed colony

Species: European earwig (Forficula auricularia)

Habitat: Woods, gardens, vineyards and orchards of Europe and North America

Desperate times call for desperate measures. As food shortages hit, European earwig babies resort to eating each other’s faecesÌęin their underground homes, helping to keep hunger and death at bay.

In times of plentiful food, the earwig offspring, or ‘nymphs’, feast on scraps of plant and insect material that their mother brings back from her trips above ground, and on .

But when faced with limited supplies, the nymphs have to make do with what’s around them to survive.

Unlike many other insects that live in groups, European earwigs don’t clear their nest of faeces. Availability of faeces in hard times keeps the nymphs alive for about two more days on average than without them, researchers have now found.

In the lab, researchers deprived 56 five-day-old nymphs of food, and offered 28 of them faeces from their siblings. Nymphs with nothing to feed on survived for an average ofÌę14 days, but those with access to their siblings’ faeces lived for an average ofÌę16 days. According to of the Johannes Gutenberg University of Mainz in Germany, this is probably because the faeces of nymphs are poorly digested, so there are leftover nutrients.

Faecal supplements

Körner’s team also presented 60 nymphs with a choice between regular food and faeces of their nest mates. A total of 48 nymphs preferred food over faeces, but around halfÌęof these supplemented their diet with some faeces – indicating that something else, in addition to the simple aim of survival, may be at play.

Munching on faeces might be a crucial way for the young to acquire essential gut microbes, says Körner.

The nutritional and microbial gains from exchanging faeces may even have kept earwig offspring from straying and probably gave rise to family life in the species, says Körner.

Earwig nymphs are not completely dependent on their mother for food: once they get past their first, crucial stage of development, they can leave the nest and fend for themselves. But the benefits of sharing faeces as food might be the reason nymphs stick around until they mature into adults.

“This is very likely to be an early form of sociality that is maintained for a long time. There is competition but some benefits of staying with your siblings,” says Körner. “You will benefit from the overall food availability even if you didn’t get enough by yourself.”

“Unfortunately, we cannot go back in time to see what environmental factors, including diet, were responsible for the evolution of social tendencies,” says Ìęat Northeastern University in Boston, Massachusetts.Ìę“So the manipulations performed by the authorsÌęare only a first stepÌęto understand the dynamics between environmental stress and sociality.”

Although the evolution of any trait is probably the end result of multiple genetic and environmental factors, she says, “the added benefit of sharing [nutrients] with others was probably one of the several factors that influenced the evolution of social behaviour in some insects”.

Journal reference: Behavioral Ecology, DOI:

Read more: Vampire squid from hell eats faeces to survive depths

Species: Metalmark butterfly, Adelotypa annulifera
Habitat: The bamboo rainforests of Peru

Keep your friends close, and your enemies closer. The metalmark butterfly cooperates with ants when it’s a caterpillar, only to stab them in the back when it has metamorphosed into a beautiful – thieving – butterfly.

While still a caterpillar, the metalmark butterfly wins over local ants, including those of the species Ectatomma tuberculatum, with gifts of sugary secretions (see gif below). In return, the ants, which could easily eat the caterpillar or its adult butterfly form, defend the vulnerable caterpillars from other predators.

But this friendly give-and-take doesn’t last forever, work by Phillip Torres of Rice University in Houston, Texas and Aaron Pomerantz of the University of Florida, Gainesville, has now revealed. When the caterpillars have become butterflies, they turn on their protectors, plundering the source of their nectar.

Ìę

This nectar is produced by organs called nectaries at the tips of new bamboo shoots, which are tended by ants. Using their mouthparts, they improve the flow from these nectaries, and stop them from running dry. The nectar is an important source of food for them, so they defend these nectaries fiercely.

Pleasing perfume

Once mature, the butterflies start helping themselves to the ants’ sugary food source, drinking directly from the nectaries in plain sight of the ants. After a few attempts to stop this, the ants give up and wait their turn.

Allowing the butterflies to feed for free is unlikely to be a beneficial move on the ants’ part. Bamboo grows very quickly, and the butterflies only lay their eggs on young shoots. When the adults are ready to breed, they fly away and lay their eggs elsewhere, meaning that the ants are unlikely to benefit from a relationship with the thieving adults’ offspring.

Torres thinks the butterflies get away with this thanks to a particular perfume. If the butterflies still smell the same as the caterpillars, this may trigger the ants to continue protecting them, in the expectation of more sugary secretion gifts.

Torres has observed some species of ant using their antennae to drum the backs of the butterflies’ bodies . This is the same behaviour they use to stimulate caterpillars to give them a sugary present.

But these ants leave empty handed – the butterflies never pay out, despite drinking from the nectar larder for hours.

To add insult to injury, the butterflies disguise themselves as ants to evade other predators. Ant-like patterns on their wings are thought to trick animals like birds that might otherwise snatch a butterfly while it was drinking nectar. “Ants don’t taste good and they have chemical defences,” says Torres.

Journal reference: Journal of the Lepidopterists’ Society, DOI:

Read more: Caterpillar drugs ants to turn them into zombie bodyguards; Parasitic butterflies dupe hosts with ant music

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