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Tubelip wrasses eat dangerously, daring to dine on sharp corals lined with stinging cells. New images reveal the fish’s secret to safe eating: lubing up and planting a big one on their dinner.

“It is like sucking dew off a stinging nettle. A thick layer of grease may help,” says David Bellwood, a marine biologist at James Cook University in Townsville, Australia, who snapped the shots with his colleague Victor Huertas.

Of roughly 6,000 fish species that roam reefs, just 128 consume corals. These corallivores specialize in different menus. Well-studied butterfly fish, for example, use their long, thin snouts to nip up coral polyps, the tiny animals that build corals. Tubelip wrasses such as Labropsis australis of the South Pacific are known for nibbling coral with their luscious lips, but until now, it was unclear what part of the coral the fish were eating or how they were eating it.
While the surface of the wrasse’s lips looks smooth to the naked eye, convoluted grooves appear under a scanning electron microscope, the team reports June 5 in Current Biology. Mucus-producing cells line each groove. In contrast, the lips of a wrasse species that doesn’t eat corals (Coris gaimard) are sleek and sport fewer slime-secreting cells.

Video footage of L. australis shows that the fish feeds by latching onto coral with its lips and sucking. The slime probably protects the fish’s lips from stinging cells that line the coral skeleton and also serves as a sealant, allowing the wrasse to get suction against the coral’s razorlike ridges.

“Their kiss is so hard it tears the coral’s flesh off its skeleton,” Bellwood says. The team suspects that the fish feed primarily on mucus layers and sometimes tissue that lines the sharp skeleton. So, essentially the fish are using their lip mucus to better harvest the coral’s mucus.
Mucus is, in general, a hot commodity in the marine ecosystem. Some fish use it as sunscreen, others for speed — it can reduce drag through the water. Cleaner wrasses even eat slime off the skin of other fish (SN: 8/2/03, p. 78).

Given the threats that coral reefs face from bleaching events and climate change, having fish that suck their flesh might seem a tad brutal. But whether the added stress of snot-eating fish serves as a mere nuisance or a serious threat remains to be studied.

Humans inhabited rainforests on the Indonesian island of Sumatra between 73,000 and 63,000 years ago — shortly before a massive eruption of the island’s Mount Toba volcano covered South Asia in ash, researchers say.

Two teeth previously unearthed in Sumatra’s Lida Ajer cave and assigned to the human genus, Homo, display features typical of Homo sapiens, report geoscientist Kira Westaway of Macquarie University in Sydney and her colleagues. By dating Lida Ajer sediment and formations, the scientists came up with age estimates for the human teeth and associated fossils of various rainforest animals excavated in the late 1800s, including orangutans.

Ancient DNA studies had already suggested that humans from Africa reached Southeast Asian islands before 60,000 years ago.

Humans migrating out of Africa 100,000 years ago or more may have followed coastlines to Southeast Asia and eaten plentiful seafood along the way (SN: 5/19/12, p. 14). But the Sumatran evidence shows that some of the earliest people to depart from Africa figured out how to survive in rainforests, where detailed planning and appropriate tools are needed to gather seasonal plants and hunt scarce, fat-rich prey animals, Westaway and colleagues report online August 9 in Nature.

The sun can’t keep its hands to itself. A constant flow of charged particles streams away from the sun at hundreds of kilometers per second, battering vulnerable planets in its path.

This barrage is called the solar wind, and it has had a direct role in shaping life in the solar system. It’s thought to have stripped away much of Mars’ atmosphere (SN: 4/29/17, p. 20). Earth is protected from a similar fate only by its strong magnetic field, which guides the solar wind around the planet.
But scientists don’t understand some key details of how the wind works. It originates in an area where the sun’s surface meets its atmosphere. Like winds on Earth, the solar wind is gusty — it travels at different speeds in different areas. It’s fastest in regions where the sun’s atmosphere, the corona, is dark. Winds whip past these coronal holes at 800 kilometers per second. But the wind whooshes at only around 300 kilometers per second over extended, pointy wisps called coronal streamers, which give the corona its crownlike appearance. No one knows why the wind is fickle.
The Aug. 21 solar eclipse gives astronomers an ideal opportunity to catch the solar wind in action in the inner corona. One group, Nat Gopalswamy of NASA’s Goddard Spaceflight Center in Greenbelt, Md., and his colleagues, will test a new version of an instrument called a polarimeter, built to measure the temperature and speed of electrons leaving the sun. Measurements will start close to the sun’s surface and extend out to around 5.6 million kilometers, or eight times the radius of the sun.

“We should be able to detect the baby solar wind,” Gopalswamy says.

Set up at a high school in Madras, Ore., the polarimeter will separate out light that has been polarized, or had its electric field organized in one direction, from light whose electric field oscillates in all sorts of directions. Because electrons scatter polarized light more than non-polarized light, that observation will give the scientists a bead on what the electrons are doing, and by extension, what the solar wind is doing — how fast it flows, how hot it is and even where it comes from.
Gopalswamy and colleagues will also take images in four different wavelengths of light, as another measurement of speed and temperature. Mapping the fast and slow solar winds close to the surface of the sun can give clues to how they are accelerated.
The team tried out an earlier version of this instrument during an eclipse in 1999 in Turkey. But that instrument required the researchers to flip through three different polarization filters to capture all the information that they wanted. Cycling through the filters using a hand-turned wheel was slow and clunky — a problem when totality, the period when the moon completely blocks the sun, only lasts about two minutes.
The team’s upgraded polarimeter is designed so it can simultaneously gather data through all three filters and in four wavelengths of light. “The main requirement is that we have to take these images as close in time as possible, so the corona doesn’t change from one period to the next,” Gopalswamy says. One exposure will take 2 to 4 seconds, plus a 6-second wait between filters. That will give the team about 36 images total.

Gopalswamy and his team first tested this instrument in Indonesia for the March 2016 solar eclipse. “That experiment failed because of noncooperation from nature,” Gopalswamy says. “Ten minutes before the eclipse, the rain started pouring down.”

This year, they chose Madras because, historically, it’s the least cloud-covered place on the eclipse path. But they’re still crossing their fingers for clear skies.

The Week 12 College Football Playoff rankings were easily adjustable for the selection committee. But they also set up to be a potentially chaotic final weekend of football.

Only one top-10 team in the most recent set of rankings lost on Saturday. That would be Oklahoma, a team the committee clearly didn't value in the first two sets of rankings, considering the Sooners' position at No. 8 overall in each of those weeks. The top seven teams remained the same following their loss, with Notre Dame, Oklahoma State and Wake Forest moving up to fill in the Sooners' spot.
A looming concern for this committee is what will happen if each of the one-loss Power 5 favorites win out the rest of the season. That could create a logjam of Oregon, Ohio State/Michigan/Michigan State and Oklahoma State/Oklahoma. That's to say nothing of the SEC, which could presumably lock up two spots should Alabama beat Georgia in the SEC championship.

Then there's the question of a potentially undefeated Cincinnati team, which if left out would join UCF as a twice-undefeated Group of 5 team that never got a chance to compete for a title.

There's still plenty of football left to be played, including the two Michigan teams vs. Ohio State in the Big Ten; Alabama taking on two ranked teams in the last three weeks of the season; Bedlam; and a not-insignificant end to the season for Cincy, which plays a ranked team in Houston.

It's all shaping up to be a wild, fun and potentially chaotic stretch to end the season. Best take a deep breath while you're still able. Until then, here's the latest top 25 rankings from Week 12:
College Football Playoff rankings 2021
Who are the top four CFP teams of third CFP poll of 2021?
Ranking Team Record
1 Georgia 10-0
2 Alabama 9-1
3 Oregon 9-1
4 Ohio State 9-1
Who are the first two teams out of third CFP poll of 2021?
Ranking Team Record
5 Cincinnati 10-0
6 Michigan 9-1
CFP top 25 rankings from third CFP poll of 2021
Rank Team Record
1 Georgia 10-0
2 Alabama 9-1
3 Oregon 9-1
4 Ohio State 9-1
5 Cincinnati 10-0
6 Michigan 9-1
7 Michigan State 9-1
8 Notre Dame 9-1
9 Oklahoma State 9-1
10 Wake Forest 9-1
11 Baylor 8-2
12 Ole Miss 8-2
13 Oklahoma 9-1
14 BYU 8-2
15 Wisconsin 7-3
16 Texas A&M 7-3
17 Iowa 8-2
18 Pitt 8-2
19 San Diego State 9-1
20 N.C. State 7-3
21 Arkansas 7-3
22 UTSA 10-0
23 Utah 7-3
24 Houston 9-1
25 Mississippi State 6-4