It was a rough year for Homo sapiens. The coronavirus pandemic highlighted our vulnerabilities in a natural world that is constantly changing. Many were pushed to find new levels of resolve and creativity to survive.

While humans quarantined, birds, bugs, fish and mammals put their own ingenuity on display. The year 2020 was when murder hornets appeared in the United States, scientists introduced us to an octopus as cute as the emoji and researchers discovered that platypuses glow under a black light.

What follows are some articles about animals — and the humans who study them — that surprised or delighted readers of The Times the most.

The longest year, the longest animal

In many ways, 2020 has felt like the longest year. It’s also the year scientists discovered potentially the longest creature in the ocean: a 150-foot-long siphonophore, spotted in the deep ocean off Western Australia.

“It looked like an incredible U.F.O.,” said Dr. Nerida Wilson, a senior research scientist at the Western Australian Museum.

Each siphonophore is a colony of individual zooids, clusters of cells that clone themselves thousands of times to produce an extended, stringlike body. While some of her colleagues compared the siphonophore to silly string, Dr. Wilson said the organism is much more organized than that.

With the world on pause, salamanders own the road

This year, amphibian migrations in the northeastern United States coincided with the coronavirus pandemic. Social distancing and shelter-in-place orders caused vehicular traffic to decline, which turned this spring into an unintended, large-scale experiment.

“It’s not too often that we get this opportunity to explore the true impacts that human activity can have on road-crossing amphibians,” said Greg LeClair, a graduate herpetology student at the University of Maine who coordinates a project to help salamanders safely traverse roadways.

He was a stick, she was a leaf; together they made history

It was a century-old leaf insect mystery: What happened to the Nanophyllium female?

In the spring of 2018 at the Montreal Insectarium, Stéphane Le Tirant received a clutch of 13 eggs that he hoped would hatch into leaves. The eggs were not ovals but prisms, brown paper lanterns scarcely bigger than chia seeds.

They were laid by a wild-caught female Phyllium asekiense, a leaf insect from Papua New Guinea belonging to a group called frondosum, which was known only from female specimens.

After the eggs hatched, two grew slender and sticklike and even sprouted a pair of wings. They bore a curious resemblance to leaf insects in Nanophyllium, an entirely different genus whose six species had been described only from male specimens. The conclusion was obvious: The two species in fact were one and the same, and were given a new name, Nanophyllium asekiense.

“Since 1906, we’ve only ever found males,” Royce Cumming, a graduate student at the City University of New York, said. “And now we have our final, solid proof.”

An octopus as cute as the emoji

What lies off Australia’s Great Barrier Reef, in the Coral Sea? The region was mostly unexplored and uncharted until a recent expedition searched its dark waters, uncovering an abundance of life, weird geologic features and spectacular deep corals.

An expedition organized by the Schmidt Ocean Institute mapped the remote seabed with beams of sound and deployed tethered and autonomous robots to capture close-up images of the inky depths.

Their work captured video of the dumbo octopus — which bears a striking resemblance to the octopus emoji — and the region’s thriving population of chambered nautili. The team also found the deepest living hard corals in eastern Australian waters and identified as many as 10 new species of fish, snails and sponges.

Time to hibernate like a hummingbird

The energy required to stay afloat in 2020 may feel similar to that used by the hummingbird. The flitting creatures famously have the fastest metabolisms among vertebrates, and to fuel their zippy lifestyle, they sometimes drink their own body weight in nectar each day.

To preserve their energy, hummingbirds in the Andes Mountains in South America have been found to go into exceptionally deep torpor, a physiological state similar to hibernation in which their body temperature falls by as much as 50 degrees Fahrenheit.

As the year ends, it may be an opportunity for us to learn from these little birds and take it slow.

Glowing up like the platypus

When last we checked on the platypus, it was confounding our expectations of mammals with its webbed feet, duck-like bill and laying of eggs. More than that, it was producing venom.

Now it turns out that even its drab-seeming coat has been hiding a secret: When you turn on the black lights, it starts to glow.

Shining an ultraviolet light on a platypus makes the animal’s fur fluoresce with a greenish-blue tint. Platypuses are one of the few mammals known to exhibit this trait. And we’re still in the dark about why they do it — if there is a reason at all. Scientists are also discovering that they may not be alone among secret glowing mammals.

Bats, the likely original source of the coronavirus

An international team of scientists, including a prominent researcher at the Wuhan Institute of Virology in China, analyzed all known coronaviruses in Chinese bats and used genetic analysis to trace the likely origin of the novel coronavirus to horseshoe bats.

The researchers, mostly Chinese and American, conducted an exhaustive search for and analysis of coronaviruses in bats, with an eye to identifying hot spots for potential spillovers of these viruses into humans, and resulting disease outbreaks.

The genetic evidence that the virus originated in bats was already overwhelming. Horseshoe bats, in particular, were considered likely hosts because other spillover diseases, like the SARS outbreak in 2003, came from viruses that originated in these bats.

None of the bat viruses are close enough to the novel coronavirus to suggest that it made a direct jump from bats to humans. The immediate progenitor of the new virus has not been found, and may have been present in bats or another animal.

Kenya has its worst locust outbreak in 70 years

“It was like an umbrella had covered the sky,” said Joseph Katone Leparole, who has lived in Wamba, Kenya, a pastoralist hamlet, for most of his 68 years.

A swarm of fast-moving desert locusts cut a path of devastation through Kenya in June. The sheer size of the swarm stunned the villagers. They’d thought initially it was a cloud filled with cooling rain.

The highly mobile creatures can travel over 80 miles a day. Their swarms, which can contain as many as 80 million locust adults in each square kilometer, eat the same amount of food daily as about 35,000 people.

While spraying chemicals can be effective in controlling the pests, locals are worried the chemicals will taint the water supply used for both drinking and washing, as well as for watering crops.

Climate change is expected to make locust outbreaks more frequent and more severe.

Millions of mink slaughtered to curb coronavirus spread

The Danish government slaughtered millions of mink at more than 1,000 farms earlier this year, citing concerns that a mutation in the novel coronavirus that has infected the mink could possibly interfere with the effectiveness of a vaccine for humans.

Scientists say that there are reasons beyond this particular mutated virus for Denmark to act. Mink farms have been shown to be hotbeds for the coronavirus, and mink are capable of transmitting the virus to humans. They are the only animal known so far to do so.

This set of mutations may not be harmful to humans, but the virus will doubtless continue to mutate in mink as it does in people, and the crowded conditions of mink farms could put evolutionary pressures on the virus different from those in the human population. The virus could also jump from mink to other animals.

Murder hornets are here for your honeybees

The arrival of “murder hornets” in the United States certainly managed to draw the world’s attention this spring.

The Asian giant hornet is known for its ability to wipe out a honeybee hive in a matter of hours, decapitating the bees and flying away with the victims’ thoraxes to feed their young. For larger targets, the hornet’s potent venom and stinger — long enough to puncture a beekeeping suit — make for an excruciating combination that victims have likened to hot metal driving into their skin.

This fall, after several sightings across the Pacific Northwest, officials in Washington State reported they had discovered and eliminated the first known murder hornet nest in the country. The nest of aggressive hornets was removed just as they were about to enter their “slaughter phase.”

Even if there are no other hornets found in the area in the future, officials will continue to use traps for at least three more years to ensure that the area is free of the hornets.