A new look at the starlet sea anemone’s stinger gets right to the point.

Live-animal images and 3-D computer reconstructions have revealed the complex architecture of the tiny creature’s needlelike weapons. Like a harpoon festooned with venomous barbs, the stinger rapidly transforms as it fires, biologists Matt Gibson, Ahmet Karabulut and colleagues report June 17 in Nature Communications.

Scientists can now see in exquisite detail “what this apparatus looks like before, during and after firing,” says Gibson, of the Stowers Institute for Medical Research in Kansas City, Mo.
In the wild, the starlet sea anemone (Nematostella vectensis) can live in salty lagoons or shallow estuaries, where freshwater rivers meet the sea. Its tubular body burrows into the mud, and a crown of Medusa-like tentacles reaches up into the water, waiting for dinner to drift by (SN: 5/7/13). Each tentacle is packing heat: hundreds of stingers that can mean death for brine shrimp or free-floating plankton.

These stingers are among the fastest micromachines in nature. An anemone can jab a predator or nab some lunch in about a hundredth of a second, says Karabulut, also of the Stowers Institute. Scientists had an idea of how such stingers worked, but until now, had never gotten so up close and personal.

The researchers used fluorescent dye to see the stingers in action and scanning electron microscopy to reconstruct their three-dimensional structure. The work reveals the precise, step-by-step mechanics of the speedy shooters.
Packed inside a stinger’s capsule, a venomous thread coils around a central shaft. When triggered, the shaft explodes out of the pressurized capsule and extends, turning itself inside out like a sock. Finally, the thread races up through the shaft, sending its barbs into an animal’s soft tissue.

Each stinger is good for just one shot. “It’s a one-hit wonder,” Karabulut says. “Once Nematostella uses it, it’s gone.”

An intelligent alien civilization could beam quantum messages to Earth.

Particles of light, or photons, could be transmitted over vast, interstellar distances without losing their quantum nature, researchers report June 28 in Physical Review D. That means scientists searching for extraterrestrial signals could also look for quantum messages (SN: 1/28/19).

Scientists are currently developing Earth-based quantum communication, a technology that uses quantum particles to send information and has the potential to be more secure than standard, or classical, communication (SN: 6/15/17). Intelligent extraterrestrials, if they’re out there, may have als
A major obstacle to quantum communication is decoherence, in which a quantum particle loses its quantumness as it interacts with its surroundings. “Quantum states you generally think of as very delicate, and if there’s any kind of external interaction, you kind of destroy that state,” Berera says.

Since the average density of matter in space is much less than on Earth, particles could be expected to travel farther before succumbing to decoherence. So Berera and theoretical physicist Jaime Calderón Figueroa, both of the University of Edinburgh, calculated how far light — in particular, X-rays — could travel unscathed through interstellar space.

X-ray photons could more than traverse the Milky Way, potentially traveling hundreds of thousands of light-years or even more, the researchers found.

Based on the findings, Berera and Calderón Figueroa considered strategies to search for E.T.’s quantum dispatches. One potential type of communication to search for is quantum teleportation, in which the properties of a distant particle can be transferred to another (SN: 7/7/17). Since the technology requires both quantum and classical signals, scientists could look for such simultaneous signals to identify any alien quantum missives.

Clouds of sand can condense, grow and disappear in some extraterrestrial atmospheres. A new look at old data shows that clouds made of hot silicate minerals are common in celestial objects known as brown dwarfs.

“This is the first full contextual understanding of any cloud outside the solar system,” says astronomer Stanimir Metchev of the University of Western Ontario in London, Canada. Metchev’s colleague Genaro Suárez presented the new work July 4 at the Cool Stars meeting in Toulouse, France.
Clouds come in many flavors in our solar system, from Earth’s puffs of water vapor to Jupiter’s bands of ammonia. Astronomers have also inferred the presence of “extrasolar clouds” on planets outside the solar system (SN: 9/11/19).

But the only extrasolar clouds that have been directly detected were in the skies of brown dwarfs — dim, ruddy orbs that are too large to be planets but too small and cool to be stars. In 2004, astronomers used NASA’s Spitzer Space Telescope to observe brown dwarfs and spotted spectral signatures of sand — more specifically, grains of silicate minerals such as quartz and olivine. A few more tentative examples of sand clouds were spotted in 2006 and 2008.

Floating in one of these clouds would feel like being in a sandstorm, says planetary scientist Mark Marley of the University of Arizona in Tucson, who was involved in one of those early discoveries. “If you could take a scoop out of it and bring it home, you would have hot sand.”

Astronomers at the time found six examples of these silicate clouds. “I kind of thought that was it,” Marley says. Theoretically, there should be a lot more than six brown dwarfs with sandy skies. But part of the Spitzer telescope ran out of coolant in 2009 and was no longer able to measure similar clouds’ chemistry.

While Suárez was looking into archived Spitzer data for a different project, he realized there were unpublished or unanalyzed data on dozens of brown dwarfs. So he analyzed all of the low-mass stars and brown dwarfs that Spitzer had ever observed, 113 objects in total, 68 of which had never been published before, the team reports in the July Monthly Notices of the Royal Astronomical Society.

“It’s very impressive to me that this was hiding in plain sight,” Marley says.

Not every brown dwarf in the sample showed strong signs of silicate clouds. But together, the brown dwarfs followed a clear trend. For dwarfs and low-mass stars hotter than about 1700˚ Celsius, silicates exist as a vapor, and the objects show no signs of clouds. But below that temperature, signs of clouds start to appear, becoming thickest around 1300˚ C. Then the signal disappears for brown dwarfs that are cooler than about 1000˚ C, as the clouds sink deep into the atmospheres.

The finding confirms previous suspicions that silicate clouds are widespread and reveals the conditions under which they form. Because brown dwarfs are born hot and cool down over time, most of them should see each phase of sand cloud evolution as they age. “We are learning how these brown dwarfs live,” Suárez says. Future research can extrapolate the results to better understand atmospheres in planets like Jupiter, he notes.

The recently launched James Webb Space Telescope will also study atmospheric chemistry in exoplanets and brown dwarfs and will specifically look for clouds (SN: 10/6/21). Marley looks forward to combining the trends from this study with future results from JWST. “It’s really going to be a renaissance in brown dwarf science,” he says.