Hello Nature readers,
Today we discover a sexual arms race between blue-lined octopuses, learn that Saturn has 128 new moons and explore how the most sequenced virus of all time — SARS-CoV-2 — changed virology forever.

How octopuses avoid being eaten after sex

Male blue-lined octopuses appear to immobilize females with venom during mating to avoid being eaten by their partners. Female Hapalochlaena fasciata have large appetites and are about the size of a golf ball — at least twice the size of males — making sex a risky business. Researchers peeped six pairs of wild octopuses in aquariums, and saw that, during copulation, females stopped breathing, turned pale and had no reflexive response to light — known symptoms of the potent venom.

Saturn has 128 new moons

Saturn officially has 128 new moons, taking the gas giant’s total to a whopping 274 — almost twice as many as every other planet in the solar system combined. All of the new moons are shaped like irregular potatoes just a few kilometres in diameter. “I don’t think there’s a proper definition for what is classed as a moon. There should be,” says astronomer Edward Ashton, who co-discovered the moons. It’s unlikely we’ll be able to spot more with current technology, says Ashton, but that’s alright with him. “I’m a bit mooned out.”

CO₂ pollution threatens self-cleaning orbit

The greenhouse effect makes part of the upper atmosphere cooler and less dense, reducing the drag on space junk that ultimately causes it to burn up. “We rely on the atmosphere to clean up our debris. There’s no other way,” says astrodynamics researcher Will Parker, who co-authoured a new study on the effects of global warming on space. With more litter clogging up low-Earth orbit, the available area for satellites will keep shrinking unless carbon emissions are cut.

D-Wave claims ‘quantum advantage’

A ‘quantum processor’ has solved a physics problem on the behaviour of magnetism in certain solids that would take hundreds of thousands of years to calculate on the largest conventional supercomputers. The result is the latest claim of a machine showing ‘quantum advantage’ over classical computers. Although Google and others have claimed to achieve quantum advantage — most lately with the Sycamore chip that Google unveiled in December — researchers at Canadian computing firm D-Wave say that their result is the first that solves an actual physics question. “We believe it’s the first time anyone has done it on a problem of scientific interest,” says D-Wave physicist Andrew King.

How SARS-CoV-2 changed virology forever

In just five years, SARS-CoV-2 has become one of the most closely examined viruses on the planet. Virologists are still sifting through the mountain of data that they collected for lessons about this virus and clues on what to watch out for in future pandemics. Sequencing the virus at an unprecedented pace allowed scientists to trace its global spread and helped them keep tabs on the mutations that gave rise to dangerous new variants. But the lessons learned are only useful if scientific and public-health institutions are in place to use them, says virologist Edward Holmes. “We’re actually in a worse place in terms of pandemic prevention than we were before the pandemic started.”

Unshackle historically Black universities

Historically Black colleges and universities (HBCUs) in the United States “are producing world-class research and record numbers of Black scientists with one hand tied behind our backs and shackles on our ankles” because of “consistent, drastic underfunding” compared to institutions established to educate white students, writes evolutionary biologist Joseph Graves Jr. “For example, my research group alone has produced more Black women with PhDs in microbial evolution in the past five years than the rest of the country has in the past five decades.” Graves calls on industry, philanthropists and individuals to shore up weakening government support for HBCUs, minority-serving institutions and tribal colleges and universities.

How to make a digital twin of the Yangtze

Managing China’s Yangtze River basin — which covers almost one-fifth of China’s land area and is home to hundreds of millions of people — is a tough job, and getting harder with rising demand for water, escalating pollution and more frequent and severe droughts and floods. Enter the Smart Yangtze River Project, with a digital twin of the Yangtze River basin at its heart. This twin consists of an advanced 3D simulation of the whole region, using data gleaned from sources that include tens of thousands of monitoring points. Eight researchers recommend steps to help the project reach its full potential, including good standards, shared data, and an online forum to support collaboration.