A paper on the shark fishery coming out in the next issue of Marine Policy estimates that we're catching 100 million sharks each year, largely to supply the Asian hunger for shark fin soup. 100 million is a really big number -- it's understandably hard to translate it into your run of the mill everyday experience. So Joe Chernov and Robin Richards (AKA Ripetungi) made a graphic to help you with that.
To be fair, the issue here is not the sheer mind-boggling enormity of the shark catch: I expect that it's dwarfed by the worldwide catch of herring or sardines. The problem is that sharks are large apex predators who take a long time to grow to maturity and reproduce very slowly. Most shark species make babies using some flavor of vivipary -- instead of spawning, their babies develop inside their moms. In some species pregnancy lasts more than a year. So sharks are classic "K strategists" when it comes to reproduction: instead of tossing millions of fry into the sea, they invest heavily in a few babies.
Worldwide indiscriminate fishing of animals that have only a few babies at a time once every year or two? Doesn't take long to eat those puppies into extinction.
Our last CSA share of the year contained a lovely surprise – three ears of popcorn, still on the cob. My kids were excited, because although our CSA also gives us a bountiful share of sweet corn in August, popcorn is much less like a vegetable. After all, most vegetables don’t explode.
Superficially, sweet corn and popcorn kernels look the same. But even if I’d taken the time to dry out some of that pile of sweet corn in my kitchen back in August, we’d only get a bunch of funny-smelling toasted kernels if we tried to pop it. Popcorn can explode because it has two things that sweet corn does not: a lot of hard starch in its center and a thick outer covering.
We can eat sweet corn kernels without breaking or grinding them first because they have a thin hull – it’s thick enough to provide a little snap when you bite through it, but not thick enough to break your teeth. You wouldn’t want to try that with popcorn. At least, my dentist doesn’t recommend it. But that tooth-cracking hull makes a dandy pressure cooker.
Put a bunch of popcorn into hot oil or air, and the starch and water inside the kernels heat up. As the temperature passes 100°C, the water starts to boil and turn to steam, but the hull keeps the steam from expanding and the pressure inside the kernel starts to climb. As superheated steam permeates starches in the kernel they soften and expand, raising the internal pressure even higher. By the time the temperature inside a kernel reachs 177°C, the liquids inside it are seething at pressures nine times higher than atmospheric pressure. If that weren’t bad enough, the heat also starts to melt and weaken the kernel wall. Soon, the kernel can’t hold back the maelstrom – its wall ruptures, releasing a tiny cloud of superheated steam and starch.
The amount of moisture in the kernel is critical: too little, and there’s not enough steam to break open the kernel. Too much, and the kernel wall melts and ruptures before the pressure climbs high enough to puff out the starch. (Those unpopped kernels at the bottom of the bowl? Probably lost too much moisture in storage.)
Once the kernel is open, the pressure of the starch cloud drops, and the rapidly expanding steam carries a film of starch outward. The type of starch inside the kernel determines how far the puff expands: hard starches stretch farther than soft ones. As the cloud expands, it cools until the starch sets into the shape of a miniature explosion – a puff that can soak up butter without collapsing or hold up a layer of hot sugar. Just the thing for a cold winter’s night.
Graph from Gökmen, 2004.
References:
Gökmen, Sabri 2004. Effects of moisture content and popping method on popping characteristics of popcorn. Journal of Food Engineering 65: 357–362
Hoseneya, R. C., K. Zeleznaka and A. Abdelrahmana 1983. Mechanism of popcorn popping. Journal of Cereal Science 1(1): 43-52.
McGee, H. 2004. On Food and Cooking, 2nd edition. Scribner: New York.
Remember yesterday’s movie of the toad eating in slow motion? Now watch this one. It’s still a toad eating a cricket, but this time it was filmed at two different temperatures. Keep two things in mind – first, the toad’s body temperature is the same as the air around it, and second, muscle works faster when it’s warm. That’s why it takes a lot longer for the toad to pull its tongue into its mouth and close its mouth at 17°C than at 24°C. But there’s no real difference in the time it takes to for the toad to fling its tongue out of its mouth. That’s because tongue extension is powered by elastic recoil. Slow muscle contractions pull elastic tissues inside the tongue tight while the toad’s mouth is still closed. When it opens, the tongue flies forward like an arrow from a bow. So whether it's hot or cold, the toad's always ready to go hunting.
There's lots of interesting biomechanics going on in this short high-speed video of a toad eating a cricket. For example, watch the tongue elongate from its own inertia as it whips out of the toad's mouth. And see how the toad's eyes start to close as it swallows the cricket at the end of the film? That's not satisfaction -- it's using its eyes to help shove the food down its throat.
There's a firm in Florida which has discovered a lovely (and profitable) spot right at the intersection of science, art, and drinking. BevShots are microscope images of crystallized beverages, photographed under polarized light. They reveal a wonderful world of color made by the substances dissolved in your favorite drinks. Ain't Science grand?
Not a lot of heavy Substance today, just a few links I found interesting.
First off: Do You Taste What I Taste? -- a neat little survey of the physiology of wine-tasting, from Slate. Turns out memories and associations have a tremendous effect on one's perception of flavor. As does the price of the bottle.
Second: Whales and Zeppelins! -- two megacool things that get even cooler together. If you're studying cetaceans, there's no better platform from which to do it than a cruising Zeppelin.
Brian Dunning, the mighty Skeptoid Debunkatron, has a really excellent post on his blog about food. He demolishes a vast amount of food quackery and silliness by zeroing in on what food is, and how the human body uses it. Mr. Dunning has a talent for this kind of thing; his early entry about "energy" is a classic of the form.
A pair of M.I.T. grad students have devised the Cornucopia, a "food printer" which uses 3-D printing technology to create . . . well . . . I don't know what.
Fortunately for everyone, the Cornucopia currently exists as nothing more than a concept and some groovy renderings. There isn't a working model yet, and let us all hope there never will be. Why am I being so harsh? Because this is the worst idea (not devised by politicians) I have seen in a decade. Apparently Amit Zoran and Marcelo Coelho, the inventors of the Cornucopia, live entirely on intravenous glucose solutions or something, because they seem to have a very odd idea of what food is and what qualities are important.
Mushrooms are one of my favorite foods. During a trip to Japan a couple of years ago I was delighted to discover that pretty much the whole nation shares my taste for edible fungi. Mushrooms for breakfast! Japan is a major mushroom producer and importer, so it's not surprising that Japanese biologists spend a lot of time studying mushrooms. Presumably most of them are not as borderline-lunatic as this guy mentioned in an earlier 'blog post.
Because they're such a favorite, mushrooms show up in Japanese pop culture -- most famously in the Mario games from Nintendo, and in the cult movie classic Matango: Fungus of Terror.
I bake a lot. But most of my creations, although I've had people rave about the way they taste, aren't going to win any beauty contests. Ginger crinkles? Round and brown. English-style gingerbread? Square and brown. Grandfather's rugelach? Light brown and blobby. So I'm consumed with envy by the science cookie creations over at Not So Humble Pie. Fruit flies, lab mice, gingerbread microbiologists, and beautiful sparkly zebrafish are just a small sampling of what Ms. Humble does with cookie dough and royal frosting. That woman wields a mean icing tube.
I know I'm too much of a klutz to even attempt most of these designs, but maybe I can manage a simple batch of petri dishes this holiday. (Aren't they awesome?)
Diane A. Kelly Diane Kelly is a Senior Research Fellow at the University of Massachusetts, Amherst, where she studies the neural wiring and mechanical engineering of reproductive systems.
James L. Cambias Jim Cambias writes science fiction and designs games in the lonely wilderness of Western Massachusetts.
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