What’s good for the ocean might be bad for the planet. Fishing boats that target specific species, leaving others free to swim away, use more fuel than vessels intent on simply scooping up all the fish in their vicinity.

Eco-label initiatives and programmes like Monterey Bay Aquarium’s , meant to help hungry diners quickly select sustainably caught seafood, have been gathering public support in recent years, says at the University of California Merced.

While those guides are helpful, their standards focus mainly on fishing-based factors, like leaving enough fish in the ocean to avoid decimating the population, and reducing the number of accidently caught fish, or bycatch, McKuin says. Other impacts, including the greenhouse gas emissions generated by using different types of fishing gear, are often overlooked.

“If we’re including climate change in the sustainability criteria, it changes things,” McKuin says.

By combing through published papers, reports, and online catch databases, McKuin and her colleague determined that tuna vessels using more sustainable methods such as troll and pole line fishing or longline fishing consume about three to four times as much fuel as boats that employ a large net called a purse seine.

Net losses

That’s because purse seining is more efficient, McKuin says – more fish can be gathered in a shorter amount of time – but it’s also less sustainable than selective methods because other species get swept into the net, too.

Thanks to a drop in purse seining in the US tuna fishery since about 1990, the team estimates that catching a tonne of tuna takes about three times as much fuel today as it did 25 years ago. The results were presented at the in San Francisco in December.

The researchers also compared the climate impact of tuna to terrestrial sources of protein, like tofu, pork and beef. They calculated the warming effect of tuna fishing based on the different rates of fuel use, and the effects of sulphur-reducing fuel regulations, which improve air quality but .

Sustainably caught tuna had a larger climate effect than any other protein considered, except beef, for which climate warming emissions are five times that of tuna per unit of weight.

And a complete accounting of the seafood supply chain could reveal even larger climate consequences, McKuin says, due to factors like the energy needed to freeze fish on its way to the supermarket.

To understand the full environmental impact of shipping vessels, including fishing vessels, we need to include all sources in our emission estimates, says at the University of Bonn in Germany.

“Nobody thinks about small shipping vessels or inland navigation vessels,” she says, but the emissions of even small ships can add up.

Read more: Beware of ‘bluewash’: Which fish should you buy?

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Gooey and tasty

It takes a village to raise a whale. Rather than sticking exclusively to their mothers’ side, baby pilot whales in the north Atlantic take turns swimming next to other adults – including both females and males.

Pilot whales are social creatures. They are thought to live in multigenerational family units of about two to four dozen individuals, says at Dalhousie University in Halifax, Canada.

Those units often gather in larger groups that stay together for up to a few weeks, allowing whales to travel, feed, rest and socialise together.

And while anecdotal evidence suggests calves sometimes accompany members of the gang that aren’t their mothers, nobody had systematically studied the behaviour in pilot whales before, Augusto says.

“People have noticed that the calves didn’t really stay with the same adults,” she says. “We would see the babies just go from one individual to the other and then jump back.”

Summer boat trip

To see if this behaviour is common among the population of more than 3000 long-finned pilot whales that spend the summer off Cape Breton Island in Nova Scotia, Canada, Augusto and her colleagues tagged along on a whale-watching boat.

From the vessel, the researchers photographed and identified specific whales based on physical marks such as nicks in their dorsal fins, scars and pigmentation patterns.

During more than 600 whale encounters over three years, the team spotted 356 identifiable calves, about one fourth of which sometimes stuck close to an adult that wasn’t their mother. One baby took turns swimming beside five grown-up companions.

Using a foam-tipped dart and a crossbow, the scientists collected DNA samples from 75 adult whales to determine their sex. Only five of those adults were identified as non-maternal calf companions — and of those, four were male.

That was a surprise, Augusto says. It is unclear why a male might let a baby stay by his side, but one possibility is that he is showing off in front of the females.

Advertising for a mate

“It’s a way to advertise that they’re a good mate, basically,” Augusto says.

The scientists didn’t notice the adults altering their behaviour when they had a young companion. That could enable the calf to observe the complex social conventions of their community, Augusto says.

“The calf might be learning from experiences with different individuals of how they should be behaving socially,” she says.

Shared parenting is something you would expect in a species with such strong social bonds, says at the Cascadia Research Collective in Olympia, Washington state.

Bottlenose dolphins and killer whales sometimes escort others’ calves, for example, and sperm whales and belugas even nurse others’ babies, strengthening the social ties of the group, or perhaps signalling to other adults that the babysitters are pulling their weight in the community.

It will be interesting to gather more details on the nature of the interactions between pilot whale calves and adults, Baird says, like how long they spend side by side, and the age of the adult male companions. If the males are relatively young, for example, they may be seeking playmates rather than pupils.

Still, Baird says, it is highly likely that calves are soaking up social understanding during the encounters.

“Calves are gregarious,” he says. “Calves are motivated to interact with other individuals when their mom’s not right around them.”

Read more: Post-menopausal orcas’ wisdom helps family survive; Orcas are first non-humans whose evolution is driven by culture

Attractive stink

Plastic everywhere

Sight and scent

Need a sugar fix? When nectar is scarce, bees can tap into another source of sweet stuff: the droppings left behind by other insects.

This honeydew, a sugar-rich substance secreted by sap-sucking scale insects, may tide hungry bees over until spring flowers bloom.

Although we tend to think of bees as hive-living socialites, are , with each female building a nest to protect her developing offspring. Adults emerge in the spring and live for just a few weeks, when they mate and gather pollen and nectar.

Fragrant, colourful flowers are like neon arrows pointing to those resources. But how wild bees survive if they mature before the blooms do was still largely a mystery, says at the University of Florida in Gainesville.

Unlike colony-building honeybees, solitary bees don’t stockpile honey for times when blossoms are scarce. “There’s really not much that’s known about what bees do when there aren’t flowers,” Meiners says.

MouldyÌęclue

But fungus-covered bushes in central California’s Pinnacles National Park seemed to offer Meiners and her colleagues a clue.

Early in the spring, before flowers had started blooming, Meiners was surprised to see many solitary bees hovering around shrubs sporting sooty mould – a fungus that thrives on honeydew – while mostly ignoring mould-free plants.

To see if the bees were indeed seeking out the honeydew, her team sprayed non-mouldy shrubs with honeydew-mimicking sugar water or plain water.

There was one other possibility to check: the bees might have been going after the mould, perhaps as nest-building material. To test that idea, a quick-dissipating insecticide was applied to mouldy bushes to stop new honeydew production while leaving the fungus intact.

The team found that the sugar took the cake. More than 100 bees visited each group of sugar-sprayed shrubs — about ten times as many as stopped by plants misted with water alone — while only about 15 bees visited the shrubs treated with insecticide.

Crucial chow

The findings may indicate that honeydew is an important food for solitary bees, Meiners says, particularly as climate change begins to shift the timings of .

But much remains uncertain. We still don’t know how the bees find the scentless and colourless honeydew. The team thinks that a bee may stumble across it when out looking for other stuff like water or minerals, recognise how useful it is and stay on the plant where it is found. Then other bees may notice that bee and investigate.

It is also unclear how much honeydew benefits bees, according to at the University of Ottawa in Canada. An interesting next step would be to see if the presence of honeydew translates into larger bee populations, she says.

And even where honeydew is plentiful, bees can’t do without flowers altogether, Forrest adds.

“They need pollen,” she says, as it is a crucial source of protein. “You can’t build a bee larva out of sugar water alone.”

Dust trap

THE huge antlers and other bones pictured here belong to an extinct Irish elk that once roamed across ice age Europe and parts of Asia and Africa.

It owes its common name to the peat bogs of Ireland, where many well-preserved specimens of its skeleton have been discovered.

Megaloceros giganteus was a Pleistocene era species whose distinctive antlers – which could span more than 3.5 metres – have inspired artists for thousands of years, from the creators of the Lascaux cave paintings to the photographers of today.

Modern studies show that the last members of the species died out about 7700 years ago in Siberia. But when Thomas Molyneux first described it in 1697, the idea that the creature was already extinct fuelled much scientific debate. Some scientists, including Molyneux, thought that living examples of animals known only through their fossilised remains were simply yet to be discovered in uncharted corners of the world. But Charles Darwin and others favoured the extinction explanation, arguing that the Irish elk, which could grow to more than 2 metres tall, would be difficult to miss.

The picture appears among a collection of 200 images by photographer Robert Clark in the book Evolution: A visual record, published next week by Phaidon.

This article appeared in print under the headline “Giant from the bog”

King Kong in a haystack

Infant-like understanding

Stop and smell the dying bees. The scent of a South African plant mimics the chemicals honeybees release when they’re under attack.

Scavenging flies on the lookout for a meal are then tricked into pollinating the plant’s flowers.

Many plants attract insect pollinators by exuding substances meant to mimic the sexy smell of potential mates or the alluring aroma of rotting flesh.

But we don’t know the details of how most of the deceptive flora hoodwink their visitors, says at the University of Salzburg, Austria.

Dötterl and his colleagues focused on solving the mystery for , a South African plant that produces “pitfall flowers”, umbrella-shaped blossoms that keep pollinators trapped within their petals for about a day, before releasing them, now packed with pollen.

To identify the plant’s pollinators, the team gathered the insects they found imprisoned within its flowers. The most common was a type of small fly that dines on the drippings left by spiders as they kill and consume honeybees.

The team wondered if the plant could be exploiting the fly’s culinary preferences to bait the insect.

“What does a honeybee eaten by a spider and this flower have in common?” Dötterl asks.

Fake attack

To find out, the scientists simulated an attack by squeezing the honeybees with their fingers or poking them with a narrow glass cylinder, then collecting the defensive compounds the bees released. The team also extracted the chemicals given off by the plant, and found several compounds in common.

Flies can perceive about half of those compounds, as subsequent experiments showed.

When the researchers left vials containing a blend of four of the overlapping substances outside, they lured in about half a dozen flies each in under an hour, while similar control vials of acetone were left alone.

“They really look for a combination of compounds,” Dötterl says, referring to the scavenging flies. That makes sense because the individual chemicals are common in nature – many plants emit one or two of them – but the mixture is unique. “We found no other organism, other than the honeybee and this flower, which releases all four compounds together,” Dötterl adds.

Cheating plants

The team’s use of multiple methods provides convincing evidence for how the flowers attract the flies, says at the University of Ulm in Germany.

“It’s a new fascinating example of chemical mimicry in plants that try to attract pollinators, and try to cheat them,” Ayasse says.

It’s also a good example of an intricate pollination system, says at Western University in London, Ontario.

“It goes to show that there are many ways to get a pollinator,” McNeil says. “The more we look, I think we’re going to discover more and more.”

Journal reference:

Read more: Orchid’s sexual deception triggers ejaculation; Plant tricks dung beetles by making its seeds look like dung

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