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Why Does Salt Kill Slugs?

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Salt and pepper go together, but salt and slugs don’t pair so well. If you’ve ever battled the slimy gastropods in your garden (or just had a sadistic bent as a kid), you know that a few pinches of salt can kill them. But why? What is it about salt that causes the creepy crawlies to wither?

The answer, in a word, is osmosis: the process that occurs when a solution meets a permeable membrane. A solution is a homogenous mixture of two (or more) substances where one substance, the solute, is dissolved in the other, the solvent. When you have a solution on both sides of a permeable membrane, the solvent tends to pass through the membrane to whichever side has more solute so that concentration on both sides is evened out. That’s osmosis.

A slug has quite a bit of water inside of it, and the cells that make up its skin have highly permeable membranes. When you sprinkle salt on a slug, it mixes with the water in the mucus that the slug secretes to help it move around, creating a salt-water solution. That solution has a higher salt concentration than the inside of the slug, so osmosis occurs and water from the slug’s skin cells passes through the membranes to dilute the solution and even things out. If you use enough salt, the slug will lose so much water that it dehydrates, dies, and winds up looking pretty shriveled.

Humans can handle salt without the same thing happening because our skin isn’t as permeable as a slug’s. Put some salt in your eye, though, and you’ll get a small sense of what the slug is going through.

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Courtesy of The National Aviary
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Animals
Watch This Live Stream to See Two Rare Penguin Chicks Hatch From Their Eggs
Courtesy of The National Aviary
Courtesy of The National Aviary

Bringing an African penguin chick into the world is an involved process, with both penguin parents taking turns incubating the egg. Now, over a month since they were laid, two penguin eggs at the National Aviary in Pittsburgh, Pennsylvania are ready to hatch. As Gizmodo reports, the baby birds will make their grand debut live for the world to see on the zoo's website.

The live stream follows couple Sidney and Bette in their nest, waiting for their young to emerge. The first egg was laid November 7 and is expected to hatch between December 14 and 18. The second, laid November 11, should hatch between December 18 and 22.

"We are thrilled to give the public this inside view of the arrival of these rare chicks," National Aviary executive director Cheryl Tracy said in a statement. "This is an important opportunity to raise awareness of a critically endangered species that is in rapid decline in the wild, and to learn about the work that the National Aviary is doing to care for and propagate African penguins."

African penguins are endangered, with less than 25,000 pairs left in the wild today. The National Aviary, the only independent indoor nonprofit aviary in the U.S., works to conserve threatened populations and raise awareness of them with bird breeding programs and educational campaigns.

After Sidney and Bette's new chicks are born, they will care for them in the nest for their first three weeks of life. The two penguins are parenting pros at this point: The monogamous couple has already hatched and raised three sets of chicks together.

[h/t Gizmodo]

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holidays
Bleat Along to Classic Holiday Tunes With This Goat Christmas Album
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Feeling a little Grinchy this month? The Sweden branch of ActionAid, an international charity dedicated to fighting global poverty, wants to goat—errr ... goad—you into the Christmas spirit with their animal-focused holiday album: All I Want for Christmas is a Goat.

Fittingly, it features the shriek-filled vocal stylings of a group of festive farm animals bleating out classics like “Jingle Bells,” “Rudolph the Red-Nosed Reindeer,” and “O Come All Ye Faithful.” The recording may sound like a silly novelty release, but there's a serious cause behind it: It’s intended to remind listeners how the animals benefit impoverished communities. Goats can live in arid nations that are too dry for farming, and they provide their owners with milk and wool. In fact, the only thing they can't seem to do is, well, sing. 

You can purchase All I Want for Christmas is a Goat on iTunes and Spotify, or listen to a few songs from its eight-track selection below.

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