What’s in a Cubic Foot of Rainforest?

by Jennifer Frazer on February 28, 2011

Rainforest on Mo'orea. Whatever you do, don't drop your keys in here. Creative Commons Tim Waters

National Geographic sent a photographer into the field to photograph every species he could find in a cubic foot of rainforest on the French Polynesian island of Mo’orea. It’s both an interesting illustration of some biodiversity (what about the microbes?) and a fun visual treat — take some time to just flip through the photographs and absorb the information visually. Don’t bother reading the scientific names (unless you must) — just read the common names, or just look at the pictures. Note the variations in shape and form.

I think they were looking much harder for insects than they were for fungi. I find it hard to believe they couldn’t find more — especially the little ones that like to hang out on rotting pieces of wood. Also: could we get a species ID on the lichen? Even to genus? A little respect, please!

In particular, notice how even otherwise dull-looking insects can have their special own beauty when viewed up close: the graceful sweep of the almond moth’s antennae, for instance, the fan dancer’s wings of the white plume moth, or the kinked wingtips of one of the kindeid moths. Other details to look for: Notice the antennae located on the snout of the weevil, and the ubercute juvenile Gump’s woodlouse. Awwww. Happy Monday, y’all.

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The ’11 Model Weird Cambrian Organism

by Jennifer Frazer on February 24, 2011

The New Weird Cambrian Organisms are in early this year, and the latest design is a trippy walking stick called Diania cactiformis(click link for image). Scientists are calling it “the walking cactus”. If Henson Studios was in charge of making life on Earth, one of their designs would probably be something like this — with googly eyes, of course.

But before we take a closer look, let’s take a step back . . .

Hallucigenia at the Smithsonian, Washington, DC. Creative Commons jylcat.

This is Hallucigenia. It is an odd creature, one who has been reconstructed both right side up and upside down (presuming only one of the directions was correct in real life, which given the general weirdness of early life, may not be a safe assumption), and which of the two the current reconstructions is correct may still be anyone’s guess. It has been interpreted variously as walking on pointy tentacles with flexible feeding arms on its back, or walking on flexible feet with pointy spines on its back (the currently favored interpretation, pictured above).

It was such an odd duck that the famous paleontologist Simon Conway Morris, whose study of bizarre Cambrian animals in the Burgess Shale Stephen Jay Gould wrote about in the book Wonderful Life,  named it after a hallucination. Morris also happened to originally reconstruct the animal in the currently non-accepted fashion, meaning perhaps that with creatures so strange, even great paleontologists can be fooled (we saw that that was the case for Anomalocaris too).

Hallucigenia was probably a lobopod, a type of creature with hollow, lobe-like legs that are extensions of the body wall. The fossil beds are full of strange incarnations of lobopods, some of which you should see here, here, and here to get a sense of the variation and general weirdness in the group.

But the creature debuted this week in nature may take the cake. (Alas — I lack copyright permission to use the images, so check out Ed Yong’s photos of the fossils here.) One cannot help but compare Diania to a first-grader’s pipe-cleaner art project. It is shockingly, wonderfully, delightfully weird. Can you imagine this thing shambling along the bottom of the Cambrian* oceans? What was it eating? How did it . . . er. . . make little walking cacti?

Aside from the delight that their sheer beauty and knowledge of their existence inspires, these organisms are important for another reason. They may have been among the ancestors of the arthropods, the tremendously successful joint-legged creatures that include insects, millipeds, and crustaceans.For, true to name, they appear to have hardened, jointed legs. But unlike arthropods, their bodies are not. The authors of the paper in Nature that revealed this creature to the world suggest that that may mean jointed legs came before jointed bodies, meaning the name “arthropod” (jointed foot) for the group was well chosen indeed.

Scientists were especially excited by the find because they had lacked any intermediate forms between the apparently soft-bodied lobopod fossils and the stiff and jointy arthropods. This looks like evidence of life in that transition.

What would Diania have looked like in real life, and how would those spindly legs have moved? Living lobopods — the modern day relatives of Diania — might give us a clue. Today, there are probably only two surviving members of the lobopod group — the velvet worms,

Creative Commons teague_o. Click for link and license.

and the water bears, or tardigrades (remember?). Tardigrades are the foil-hatted survivalists of the animal world, withstanding pure alcohol, the vacuum of space, temperatures from -272 to 149 degrees C and ionizing radiation with remarkable aplomb. It’ll be them, cockroaches, and twinkies in the fallout of the apocalypse. Yet belying that ability is their adorable plush appearance, as they trundle along on their cute little claw-footed stumpy legs, as you can see in this video.

They can live practically anywhere — from moss to the deep sea to hot springs.

Velvet worms, on the other hand, are skilled predators with an incredible way to snare their prey. As usual, David Attenborough puts it best in this video:

Download:

FLVMP43GP

They tend to be arrestingly textured, brightly colored or even iridescent, and favor moist places, perhaps because their somewhat-hardened skins are not very water-tight.

Although both velvet worms and water bears have somewhat hardened coverings that they periodically moult and stumpy conical legs that end in claws (like many fossil lobopodans), they are not jointed. Scientists have been confused by their relationships to each other and to the arthropods. They have many traits in common or diverging from the arthropods and each other. Velvet worms, in particular, have stirred up controversy, having been suggested to be everything from slugs or polychaete worms to degenerate arthropods that are close insect and millipede relatives to one-half of some sort of unholy hybrid velvet worm-butterfly union that produced caterpillars (most scientists have scoffed at this).

As a result, most trees depicting the relationship have shown water bears, velvet worms, and arthropods as a three-tined fork on the Earth family tree. All the extinct lobopods fit in and around these branches. If you were going to stick Diania in there, as the authors of the Nature paper do, you’d place it closer to the arthropods than either the water bears or velvet worms, making a new two-pronged fork. Though it’s possible Diania is a direct ancestor of arthropods, it may be more likely that Diania mearly shares a similar looking common ancestor with arthropods and ultimately represents a failed life experiment. Those of you craving a closer look that incorporates a host of extinct Cambrian fauna on a hypothetical tree can find a more detailed one from the paper here.

Phil Plait (the Bad Astronomer) likes to say,”The universe is cool enough without making crap up about it”, or something like that. Diania — and Hallucigenia, and water bears, and velvet worms — certainly seems to help make his case.

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* the time period of the second major explosion of multicellular life — the one that generated the ancestors of most modern critters

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The Joy — and Pain — of Marine Census Taking

by Jennifer Frazer on February 19, 2011

If you looked at the abyssal plain from afar, you might think it was one giant, boring mud flat. Ahhh, not so. The plain is alive . . . and scientists are busy sifting it to see what’s there . . .

To get to be the one to sit down in front of that microscope would be both blessing and curse. Can you imagine the excitement of looking into the eyepieces and not knowing if you’ll see something completely new to science? And getting to do this for your job? It’s like Christmas every day . . . interspersed by long periods of soul-crushing tedium as you see predominantly the same species you looked at in the last 15 samples, I’d imagine. 20 samples with 50 to 100 species each? You can do the math on that.

In spite of what they say in the film, nematodes — tiny roundworms found in great abundance in soil and water all over the planet — are actually not very closely related to earthworms (annelids), at least according to studies of their DNA and RNA. Though they’re both protostomes — a major division of the bilaterally symmetrical animals characterized by embryos in which the first dent that forms in the embryonic ball becomes a mouth — nematodes are in the ecdysozoa, or the exoskeleton-shedding invertebrates like insects and arthropods.

Annelids(including earthworms), on the other hand, are in the other great protostome division, the lophotrochozoa. This division notably include the moss-animals (remember them?) and the molluscs (snails, octopuses, squid, chitons, bivalves, etc.). Members of this group either have trochophore larvae with bands of cilia around their middles, or a lophophore, a crown of fan-shaped cilia surrounding — and provisioning — the mouth.

In any case, the take-away point here is that although nematodes and annelids are both worms — a perfectly good informal term for a long, legless creature that has only to do with the way a creature looks, not its evolution-based taxonomy — that doesn’t make them closely related. Evolution, in its directionless wandering, often fools us that way. Have a look at the tree here.

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The Pink Meanie Menace

by Jennifer Frazer on February 16, 2011

Sai, hooman, ware can I finds anutter jelli to nom? The pink meanie, Drymonema larsoni. Credit: U.S. Geological Survey Department of the Interior/USGS U.S. Geological Survey/photo by Harriet Perry

It’s no secret that jellyfish are capitalizing on the giant hole in the ocean left by our past (and in some cases, continuing) strip-mining of its waters for seafood, baleen, and whale oil. Their populations have blossomed like a Dutch tulip market. But now it seems another population may be benefiting from the open water rush: cannibal jellies*.

Scientists recently discovered an entirely new species of jellyfish-eating jellyfish, the colorfully named “pink meanie”, according to a recent article in The Biological Bulletin. According to a USGS report, no one had reported or could recall seeing a single pink meanie in the waters off of Puerto Rico prior to 1999, and no one could tell what species it was.

Yet that year, scientists estimated an explosion of some 25 million meanies. That’s a lot of meanies. But it’s not nearly as many as the boom of common moon jellies they were feeding on around Puerto Rico that year: an estimated two billion.

Is it possible we are only noticing this heretofore reclusive or minor species now because jellyfish prey pops are blossoming, and the environment is primed for jellyfish-eating jellies to do well? Food for . . . er, thought.

There’s certainly no question that pink meanies are good at eating moon jellies. One pink meanie was found with its tentacles stuffed with 34 moon jellies. That is not, as my father would say, a lady-like sized bite. Nor is this: look carefully at the diameter of the bell of the nearly transparent moon jelly in the third photograph in this slideshow. It is huge! Either the pink meanie has moxie . . . or it’s an eyeless and nearly brainless invertebrate with a voracious appetite. One of those two.

Originally, scientists thought they might have found an invasive species from the Mediterranean and Atlantic called Drymonema dalmatia. But closer investigation revealed molecular and morphological differences signficant enough to warrant a new species designation. What’s more, they decided that the uniqueness of the entire Drymonema group was such it should be in its own family:

This revision emphasizes the remarkable morphological disparity of Drymonematidae from all other scyphomedusae, including allometric growth of the bell margin distal of the rhopalia, an annular zone of tentacles on the subumbrella, and ontogenetic loss of gastric filaments.

As far as I, <echo chamber> A Trained Biologist </echo chamber> can figure, that means something like that the bell is scalloped rather than smooth-edged (see pictures), the tentacles emerge from a ring-shaped zone rather than in clusters, and they lack from the beginning of their development the stinging stomach filaments that kill any food that manages to reach standard jellyfish stomach pouches alive. Somehow I’m imagining the loss of something you might find in the center of a sarlacc pit, but it’s probably not that awesome. Please, jelly experts, help correct me if I have misinterpreted.

For those of you interested in Extreme Closeups of this jellyfish’s color, anatomy, and texture (including the scalloped edges), see here.

Sadly, though these jellies feed on other jellies and may help to control their populations, they are still jellyfish, they still have stingers, and the stingers can still hurt humans. But (and this is just a guess) they probably cannot hurt other jellies enough to stop their relentless takeover of the increasingly undefended turf in Earth’s oceans**.

These jellies fall into to the major group Scyphozoa (sky-fu-zo-uh), the “true” jellyfish. The name comes from a Greek drinking cup whose shape jellies are supposed to resemble. They, in turn, are one of four major groups in the phylum Cnidaria (Nye-DAR-ee-uh). Their close relatives in the phylum are the Anthozoa — primarily the sea anemones and corals, including the sea fans, sea pens, soft corals, organ-pipe corals, tube anemones, stony corals, and black corals — the Cubozoa, or deadly box jellies, which I was mighty afeared of bumping into on my pelagic night dive last spring, and the Hydrozoa, or hydroids, fire corals, man’o’war jellyfish, and by-the-wind sailors.

Your homework: See how they fit together here at the Tree of Life, or hit up the Google with one of the names that intrigues you to see what it’s all about. I assure you, the creatures in these groups are some of the most amazing on Earth.

And lest you think I have a pathological hatred of jellyfish, know that I have an entire bathroom decorated in a jellyfish theme — including one plush jellyfish and one glow-in-the-dark jelly. Yes, my nerdiness knows no bounds. Plans are also in progress to create an entire lichen- or Haeckel-themed room . . .

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*Of course, that’s not really accurate. Unless they’re eating members of their own species (which they may well), they’re still just predators who happen to feed on their close relatives. That’d be like saying hunans who eat monkeys or apes are cannibals.

** Wanna do something about it? Download a seafood watch wallet card and use it when you are buying seafood or sushi. You could also consider supporting the ocean conservation organization of your choice. And of course, do what you can to fight climate change/ocean acidification. I don’t need to tell you what those things are.

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Mosses That Move and the Rocks They Reveal

by Jennifer Frazer on February 7, 2011

Many of you may know about the Racetrack, the mud-cracked waste at the north end of Death Valley that is home to the mysterious sailing stones.

See, if you tilt the camera, the rocks slide downhill. Wait. . . let me check my notes . . . A photograph of the fascinating Racetrack Playa in Death Valley, California, USA. Creative Commons djfrantic. Click for link.

It turns out there’s a perfectly cromulent explanation for this effect; if you don’t know it and want to spoil the magic, see here.

Well, it turns out that this organism,

Sooooooo cute. I'm waiting for the plush version from Etsy. Grimmia trichophylla. Creative Commons johndal.

or one of its close relatives, I should say, can apparently do the same, or something like it. Don’t believe me? There were three photographs and a fascinating account of the phenomenon over at Botany Photo of the Day last week — the most important bits are paragraphs two and three. Don’t miss it! Once you’ve read it, come back here for a little commentary . . .

OK, finished?

Now, my friends, you can see why geologists hate “vegetation”. For in addition to your garden-variety and annoyingly rock-obscuring trees, shrubs, flower, and soils, they must also contend with the biofilm of lichens — little fungus-alga co-ops — and naked algae that encase every rock in sight after a few decades. That means that nearly every rock face you look at is not its true color; it’s the color of the encrusting life. The day the light bulb blinked on and I thought, “That cliff isn’t gray-green. The rock is pink and the stuff living on it is gray,” was one of revelation for me.

This further explains why geologists flock to newly blasted road cuts like flies to honey, and further why they carry around rock hammers* for splitting rocks to see what they truly look like. It also explains why I get nervous around them when they get that glimmer in their eyes suggesting that if they could napalm the countryside in their research area, they would.

When I reach the summit of mountains in Colorado, I’m astounded by the variety of lichens, moss, and algae I find there. Mountaintops are lichen biodiversity hot spots, splashed with green, yellow, black, gray, and orange.

A fiesta of lichens (can I coin that term for a lichen herd?) at Rocky Mountain National Park. Creative Commons shrocket.

Thrillingly orange lichens are particularly common up there, since they thrive in places birds poop (and thus fertilize), and birds seem to like perching on rocks near the summits of mountains where they, like us, have a clear view of the countryside. And yet, almost no one looks down or looks carefully, and with enough foot traffic, the encrusting life dies and peels off.

Apparently, mosses can also induce lichen holocausts as they slide down rock faces. How they do this, I know not, although the lack of light may play a role. But notice there aren’t simply dead lichens in their wake; the rock is scrubbed clean. Which leads to another interesting hypothesis: the moss excretes acids or some other chemicals that allow them to digest the biofilm on the rock surface and absorb the resulting nutrients. Would that make these mosses . . . herbivores?

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*Also because physical and chemical processes called “weathering” alter the surfaces of rocks. Also, by coincidence, they note that in the first two photos of the galloping moss, they are galloping upon the fossils of 1.9 billion year old cyanobacterial mats — thin films of blue-green bacteria that slowly build up characteristic striated rocks called stromatolites. In ancient times, these were prolific and their fossils are common, but today, stromatolites, crowded out by us pesky multicellular organisms, are found in only a few places on Earth, most prominently in the Hamelin Pool in western Australia’s Shark Bay. Interesting biological coincidence!

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Lake Vostok: Out of Reach for Another Year?

by Jennifer Frazer on February 6, 2011

Image by Nicolle Rager-Fuller/National Science Foundation.

It’s looking less likely Russians will reach unexplored sub-Antarctic Lake Vostok this year. A few weeks ago I wrote about their attempt to drill into one of the last frontiers on Earth — one that could be home to incredibly interesting unknown life. Today is the last day — if they don’t make it now, it won’t happen until next season. From Science:

Russian scientists drilling toward Lake Vostok, an enormous body of fresh water sealed off beneath Antarctic ice for 35 million years, have until Sunday to reach their goal before flying out at the end of the summer field season, NPR reports. But with less than 30 meters to go, it’s looking like they’ll fall short and have to resume months later. “They didn’t get to the moon first; they really, really want to be the first people to drill into a subglacial lake. And they want to do it right,” geoscientist Robin Bell of Lamont-Doherty Earth Observatory in Palisades, New York, told NPR.

And here is a more in-depth account from NPR. It reveals there may indeed be some friction over the perhaps characteristic Russian methods noted in my last post on Vostok (anyone who knows about the differences between the US and Russian space programs will understand what I mean. We just have different risk tolerances):

Jim Barnes has been watching this process closely, as head of a nongovernmental organization called the Antarctic and Southern Ocean Coalition.

“Well, to be perfectly honest, we’re not very happy about it,” he says.

One major concern is the Russians have filled the hole they’re drilling with more than 14,000 gallons of kerosene and Freon to prevent it from freezing shut. The Russians have engineered their system so that when they break through into the lake, water pressure from below is supposed to push the drilling fluids up the hole, rather than letting them pour into the lake and contaminate it.

But Barnes is nervous. He’d prefer that the Russians used more environmentally friendly drilling systems that use hot water and don’t need kerosene and Freon.

“Nobody needs to go into this particular lake — or any particular lake — tomorrow. There’s no driving need for it,” Barnes says. “Why take risks that are unnecessary?”

Their plan was to swap out the kerosene for “clean” drilling fluid within a few dozen feet of the lake surface. But what if the surface is higher than they anticipate? Knowing now that hot water was an option, I’m more skeptical of this effort.

The NPR piece goes on to note that the incredible pressurization of the lake’s water by gas (I compared it to a two-liter of soda having a fun night with a paint shaker last time) could mean that once they pop the top, the whole thing could blow like a oil-field gusher in Texas, spewing the contents of the lake into the air over Antarctica until the entire system is depressurized. Fun. I do think it’s important to explore the lake, but safely  — for the lake and for us. Whether they make it this year or not, I do hope they get it right.

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This Week in Formerly Terrifying Prehistoric Marine Life: Giant Sea Scorpions

by Jennifer Frazer on January 31, 2011

Your base model Sea Scorpion. Extra option package includes scary-looking spiked chelicerae (feeding mouthparts). Creative Commons Ryan Somma. cc-by-sa-2.0. Click for link.

A few months ago I wrote about a study by scientists at the Denver Museum of Nature and Science that showed the mighty Anomalocaris — the “terror” of the Cambrian seas — might not have been so mighty after all. Well, it’s happened again.

This time, the victim is the sea scorpion — members of the class Eurypterida (the eurypterids, “you-RIP’-ter-ids”). These remarkable creatures roamed mid-Paleozoic shallow waters, both saline and fresh, and some may have even crawled onto land to curl up in the hollow boles of tree lycopods. Though many forms were smaller, paleontologists have unearthed fossils of some marine forms that can reach seven or eight feet long, making them possibly the largest arthropods ever (and that’s saying a lot, since arthropods include all the crustaceans, insects, and arachnids).

Their fossils look a bit like scorpions that got squashed with their pincers pointing backwards — although actually, the “pincers” are the last pair of legs, modified to be paddles for swimming. Some of the squashed look may actually be due to fossilization, but probably not all — horseshoe crabs, which are also joint-legged, armored arthropods, look pretty much like they do in real life in fossil form. In short, they resemble a creature that would crawl into and nest in someone’s ear in Star Trek.

Here is how Colin Tudge describes them in The Variety of Life:

Eurypterida superficially resembled scorpions, but sometimes grew as long as a small rowing boat, and were among the most prodigious invertebrates of all time. Eurypterids should be remembered with the kind of awe with which we contemplate dinosaurs. […] Like dinosaurs, eurypterids have a sobering, Ozymandias-like quality; that such magnificent creatures, which flourished, radiated, and often dominated for nearly 250 million years, should finally have gone the way of all flesh. It would be good to have just one survivor to admire.

Up until a few weeks ago, it was thought these behemoths, along with predatory ammonites — relatives of octopus, squid and cuttlefish — were the top predators of mid-Paleozoic (the time from the Cambrian explosion to the Permo-Triassic extinction, the Great Dying that preceded the age of dinosaurs) seas. Only with the rise of jawed fishes (think sharks and placoderms) did they lose their dominance. Well, at least according to a new study, maybe not so much.

This time, scientists at the Buffalo Museum of Science in Buffalo, N.Y., were the guilty parties. They calculated once more the force required to crack into the shells of the kind of prey it’s thought sea scorpions ate — horseshoe crabs. The force the spiny pincers of a representative of one of the largest groups could produce, they found, came up short in the  crab shell cracking department. About three to 12 pascals short, to be precise. What is left for our subject? Scavenging, perhaps, or (gasp!) vegetarianism, the scientists suggest.

Interestingly, eurypterids are actually, in addition to being arthropods, chelicerates. You know, chelicerates — the spiders, scorpions, ticks, mites, etc. — all animals in possession of special food-nabbing (and often food incapacitating and venom injecting — chelicerae are the things on spiders with fangs) mouthparts called chelicerae (che-LISS-er-ee). Guess who else are chelicerates? Horseshoe crabs.

Check out how eurypterids fit into the chelicerates and arthropods here. You’ll notice that in spite of their name, sea scorpions aren’t actually closely related to scorpions.The little cross (technically, a dagger) next to the group means that it has bit the big one, sadly, at the end of the Permian in the aforementioned Great Dying, unless we find some hiding out in Lake Vostok.

Will these results stand up when tested by other scientists on other specimens? Were Anomalocaris and the eurypterids really wimps? And if they weren’t the biggest, baddest, things around what was? And what’s next? T. rex a lowly scavenger? Heaven forbid.

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The Borg of the Microbes Takes Up . . . Farming?

by Jennifer Frazer on January 26, 2011

You are witnessing one of nature's most incredible migrations that never gets shown on the Discovery Channel. Believe it or not, each one of those little dots is a solitary amoeba. But not for long.

Note: This post contains a prize inside! It will await those patient enough to dig to the bottom. : )

Regular readers of this blog know well about my weakness for the protists formerly known as slime molds (scientists know apparently prefer the more PC and sexy “social amoebae”, although how you can get much sexier than “slime mold” I really don’t know). Exciting news came this past week that a species of cellular slime mold — Dictyostelium discoideum — contains members who have taken up bacterial farming (or at least husbandry — more on that distinction later). I ask again — slime molds: is there anything they can’t do*?

Before we get into their new status as potential FFA members, let’s talk a little bit about this particular group of slimes. So far on this blog, I’ve told you primarily about a group informally called “plasmodial slime molds”. This is the kind that make big, colorful slimy slicks that rove the forest floor wreaking microbial havoc as they vacuum up any bacteria, yeasts, and protists in their path, and then blossom into beautiful bright fruiting bodies like the one in the masthead of this blog.

But there is another kind of slime mold. One that, while perhaps less glamorous, is even more crafty and incredible: the dictyostelids, or cellular slime molds. What is the difference? Well, if plasmodial slime molds are amoebas that discovered living large, cellular slime molds are amoebas that discovered living social. In a plasmodial slime mold (also called myxomycete or myxogastrid), two amoebae meet, decide to spend the rest of their lives together, fuse, and then that fused cell starts dividing mitotically, or asexually, like it’s going out of style to churn out hundreds or thousands of genetically identical nuclei inside one big happy bag of cytoplasm.

In a cellular slime mold, something even more remarkable happens: a single amoeba called a myxamoeba suddenly decides it is starving. As a result, it secretes a molecule called cAMP as a distress call**. And suddenly, hundreds, thousands, hundreds of thousands of amoebae amplify the call by emitting their own cAMP, and begin streaming in toward Amoeba Zero in pulsating waves. They get sticky, climb on top of each other, and cling together. The pile towers up. And then, if it’s not sufficiently bright enough, the tower topples and begins sliming around like a slug. It’s now a single multicellular organism — made of 10,000 to 125,000 amoebae who still retain their individual membranes and identities. Yes, like the Borg — if they were all crazy-glued together. And if they intermittently all lived happily on their own before feeling an irresistible pull to join something called a “collective”.

Take a look at this process:

That aggregation star at left is a schematic of what you're seeing in the image at the top of this page. Tijmen Stam, IIVQ (SVG conversion) - user:Hideshi (original version) GFDL + CC-BY-SA, click image for link.

After crawling far enough to reach an area deemed suffienctly light (I imagine this it to raise the odds of being in a windy, spore-dispersally spot), the slug coalesces into a sombrero-shaped mass from which some of the cells begin gliding upward along a stalk like an elevator. At the apex, the elevator cells convert themselves to spores. Ultimately, they blow away in the breeze to (hopefully) more bacterial pastures.

Now take a look at this process in action.

  • First, here’s an overview from my alma mater — the Plant Pathology department at Cornell (Try the downloadable versions if the player doesn’t automatically load or if you want to watch a high-res version (recommended)). Watch the perimeter and the background. Note slugs wandering about looking lost.

And it gets better — or worse, depending on your perspective. Some of the amoebas in the slug must voluntarily sacrifice themselves (a process called programmed cell death, or apoptosis. It’s basically microbe seppuku) to form the long stalk. This seems to be determined primarily by what phase of the cell cycle they were in when they reached the forming slug; the last cells to arrive will form the tail of the slug, and the early-arrivers at the head of the slug will become the sacrificed cells of the stalk.

But in an entity where not all cells are genetically identical, you can see how it might be tempting (and much more reproductively successful) to shirk stalk duty and climb your way to the top come hell or high water — that is, to cheat. And in fact, it turns out cellular slime mold myxamoebae do sometimes cheat their way to reproductive success. Scientists fascinated by this have studied it a lot.

That brings us back to farming. Because in addition to being cheaters, some Dictyostelium also appear to plan ahead in other ways. Like packing lunch — or perhaps the seed of lunch. They bring their preferred bacteria with them and seed the soil where their spores land. It’s a little too early to tell if they just eat what they brought or wait sufficiently long for what they brought to reproduce a bit. But the evidence so far seems pretty conclusive: some D. discoideum spores are packin’ bacteria. Though whether they are packin’ them inside or outside the spore wasn’t entirely clear to me either. Only 1/3 of the samples they tested were farming amoebae, but that may be because it does come with a price. Farming amoebae are fitter in times of starvation, but less competitive than non-farmers in times of plenty. Having both strains around makes sense in a world of changing conditions.

Because they don’t weed, water, or fertilize their future food, some scientists suggest it might be better termed husbandry than farming. Whatever you call it, these are the first microbes ever known to do it. Cool***. And the reason, scientists told National Geographic, is that these are also the only microbes that are social — being social enables wind-blown, stalk-borne dispersal, which makes bringing bacteria worth it at all. And so far as we know, all the planet’s other farmers are all social organisms as well. EEEN-teresting.

From Science magazine’s writeup:

Koos Boomsma, an evolutionary biologist at the University of Copenhagen who did not work on the study, is not surprised that farming is scattered through the tree of life. “But if I would’ve had to predict where I would have next expected farming to be discovered, I would never have predicted a slime mold,” he says.

See, this is exactly what happens when we underestimate slime molds. And you all thought I was kidding about that world domination thing . . .

This discovery got full court press coverage; you can read more about it here, here, here, here, here, and here.

When first discovered, slime molds — both plasmodial and cellular — were thought to be fungi, hence the “mold” bit. But unlike fungi, they have cellulose cell walls (like plants and some other protists, but not chitin, like fungi) and cellular organelles called centrioles (like animals). Moreover, the two groups were not thought to be closely related to each other****. Now we know that although there are other types of slime molds that do not fit into these two groups, the plasmodial and cellular slime molds are true taxonomic groupings reflecting common ancestry, and that the two groups are fairly closely related: they are both in the same taxon as free-living amoebas — the Amoebazoa (look for the group on this tree, and then click on it to explore. Notice on the big tree they’re on the same branch with animals and fungi). Which makes sense — slime molds all begin life as ordinary looking amoebas.

Now bear in mind Dictyostelium, for all its transcendent coolness, is but one species among many — perhaps hundreds or thousands. What are other cellular slime molds like? Well, we may not know what many or most of them are like, since so few people study them. But below are videos (your treat for making it all the way to the end of this post) of a spectacularly beautiful other species of cellular slimes, Polysphondylium violaceum (Paul-ee-sfon-dil’-ee-um vie-o-lace’-ee-um — say that three times fast). Unlike Dictyostelium, it does not make roving slugs (though it does aggregate), and it uses a chemical called glorin, and not cAMP, as its chemoattractant. Watch the complex fruiting bodies — or sporocarps — form in these time-lapse movies again from my old buds in the Plant Path department at Cornell.  Notice in particular the branching and the purple pigment — it’s like a fireworks display in slow motion. Try pausing the videos just before the end for a nice still. And again, try the downloadable versions — they’re much higher quality images anyway.

  • Video 1 — close up
  • Video 2 — wider angle, different sample, even more spectacular display

Yes. Ameobas can do that.

Finally, ponder this: Dictyostelium, and the cellular slime molds as an entire group — was not discovered until 1935 in a North Carolina forest. 1935. Now ponder all the other amazing stuff that must still be out there, just waiting.

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*Perhaps home decorating.

**cAMP is a ubiquitous Earth signaling protein found in organisms from humans to bacteria. It’s a stripped down ATP ( the energy currency of the cell) used, essentially, as one of several master switches for turning circuits (metabolic pathways) on and off in the bioreaktor/ Brownian chaos computer of the cell (Many, if not most, of the biochemical reactions of the cell are governed merely by the rate at which molecules happen to randomly bump into one another (implication: more molecules will make the reaction go faster). Even proteins chaperoned to important reactions by other proteins must bump into their chaperones in the first place.) In social amoebae, cAMP takes up the somewhat novel role of chemical attractant — that is, a pheromone.

***There are a few more lurid and/or fascinating bits to the cellular slime mold story. For one, lest you think their asexual reproduction was the only weird thing about them, Dictyostelium sex is also kinda creepy. It starts out normally: two amoebae meet and fuse. But things get weird fast: the zygote (diploid, or double-chromosomed) offsprings goes on a cannabilistic rampage, engulfing all nearby amoebae as fast as it can. When sated, the cell wall thickens with cellulose to form the resting spore, or macrocyst, that can survive tough conditions. Before it germinates, the cell undergoes meiosis, or reductive cell division, to get back to one copy of chromosomes per cell, and then several mitotic, or regular, cell divisions before it releases its little myxamoebas when conditions are good.

**** From my late-90s botany book: “The plasmodial slime molds, or myxomycetes, are a group of about 700 species that seems to have no direct relationship to the cellular slime molds, the fungi, or any other group.”

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Corrupting Life

by Jennifer Frazer on January 18, 2011

I knew it would be bad when I heard Oprah Winfrey was replacing David Attenborough as the narrator of the American version of “Life”. But I didn’t know it would be this bad.

David:

(If this is taking too long to load or is playing too jerkily, go here.)

Oprah:

Actually, it’s even worse than this in the version I saw in “Challenges of Life” episode: they cut the sound effects (stopwatch and slamming noises), altered and dumbed down the narration further, and cut the scenes of the flies suffering at the end. Apparently, in addition to subbing Oprah for David, they rewrote the script in many places and replaced it with a hack job a freshman biology student appears to have penned. (Sample dialogue: “The thing about mating is, that it has some fairly predictable consequences.” ) Worse, they replaced the beautiful soundtrack with the cheesiest Musak they could find, changed the sound effects, and cut, changed the tone, or destroyed the narrative of some of the most poignant scenes (possibly for time since Discovery Channel, unlike BBC, has commercials). The American title sequence was so bad (and sooooo different from the moving yet understated British opening to Planet Earth with the sun dawning over the planet in an inky black sky) that I thought it was yet another preview or commercial. Shame on you, Discovery Channel. SHAME.

They even changed their facts in some places. In the American version, Oprah claims some grebes are Western grebes, and that they are monogamous but switch partners every season. In the British version, David says the very same grebes are Clark’s grebes and that they mate for life. So which is right? I’ll put my money on David. How many more inconsistencies are there? I only noticed these because I happened to have seen a preview of the British version of this scene.

Completing the Failure Trifecta, Netflix ONLY offers Americans the corporate pablum Oprah version. That’s right, America. You aren’t even considered bright enough to be given the option of watching the grown-up British version. Shame on you, Netflix. SHAME.

Don’t believe me? Think I’m exaggerating for effect? A (non-random) sampling of customer comments from Netflix:

Oprah Winfrey narrating Life in place of Sir David Attenborough is like having Donald Trump narrate for Jacques Cousteau. The one with the original audio will be out later, and I’ll be waiting for that one. (From a one-star reviewer)

This would be a 5+ Rating if it wasn’t dubbed over by Oprah Winfrey without any way to change it back to the original Attenborough. Epic Fail to not include the original language, and epic fail on NF for choosing this version over the original. (Yet another one-star review)

I too would give it 5 stars only if Oprah hadn’t ruined it. I’ve since purchased the Sir David Attenborough’s narrated version so that I could enjoy the rest of the series and would agree with many others, Oprah shouldn’t be narrating anything regarding the natural world – corporate explotation in my opinion. (You guessed it — one-star review)

Please bring the David Attenbourgh version to NF. I’m sure the Oprah version was cheaper (no one is buying it), but there was a reason for that. I had real trouble with the fact that the narrator cannot pronounce the words correctly.

What the heck??? I thought this was supposed to be narrated by Sir David Attenborough? Instead Oprah Winfrey sounds like she is narrating for a group of children… this is insulting. I had to turn it off, and I am going to order the Original BBC version.

You cannot substitute David Attenborough. His love and knowledge for nature is unmatched. You can’t have someone like Oprah narrate this. It’s an attrocity. I couldn’t finish watching the last bit of it because I wanted to punch Oprah.

It was so unwatchable and so unrecognizable as the original, high-quality product I’ve come to know and expect from the Beeb that I’m sending my DVD back and refusing to watch further until the powers that be at Netflix release the Attenborough version from its corporate prison. Come on, Netflix. Do the right thing.

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Earth’s Real Lost World — and its Imminent Entry

by Jennifer Frazer on January 13, 2011

The warren of lakes beneath the Antarctic Ice Sheet. Zina Deretsky/NSF

Far more exciting to me than the (in my opinion) remote possibility of life on other worlds in our solar system is the near-guarantee of the discovery of unique life that could happen within weeks right here on Earth. For hidden beneath the thick layer-caked ice sheet of Antarctica is a lacy web of lakes that have been sealed in for perhaps 15 million years. And soon — perhaps this month — Russian scientists will breach the last veil of ice blocking our view of the biggest: Lake Vostok. The titanic lake — roughly the size of Lake Ontario and with a maximum depth double that of Lake Superior (2600 ft. vs. 1300 ft) and discovered only in the 1970s — lies under two and a half miles of ice.

Since there is virtually nowhere on Earth that life doesn’t thrive, I fully expect scientists will find it there. And it may be life that is unlike any other we have seen. We’re not just talking weird bacteria (although that would be AWESOME). There could be blind, bizarre fish, or other large organisms beyond our wildest imagination (although, it must be said, we have no evidence (so far) of a large energy source for the lake, so microbes might be it). Use your imagination — until they break through, you can imagine anything you want down there — trilobites, krakens (per one New Scientist reader), Nessie. THIS is incredibly exciting news.

There are several reasons to think the life in Antarctica’s Lake Vostok (Russian for “East”) might be seriously unusual and wonderful. First, it hasn’t been touched by humans. There was very little you could say that for even before the Age of Discovery — humans had touched nearly every terrestrial corner of the planet. You could make a good argument for many cave ecosystems where humans did not tread until this century. And they have unique life aplenty, but they also have water, life, and even pollution that percolate in from the surface on a regular basis, even where no (wo)man has set a foot. Not these lakes. To the best of our knowledge, they have been sealed to the outside since the ice sheets formed.

Second, the water of Lake Vostok is unlike water in virtually any other spot on Earth. It’s under enormous pressure thanks to jillions of tons of ice, and as a result, is super-oxygenated. We’re talking oxygen concentrations 50 times that of your backyard pond. And it must be said that oxygen is not the nicest of molecules from life’s perspective. Although properly harnessed, it’s a great power source, it’s also a bit like rocket fuel: volatile and reactive. Oxygen breakdown products called free radicals are like molecular loose cannons: capable of wreaking  havoc on DNA and other important cell bits. Accepting oxygen into your life (some bacteria — obligate anaerobes — refuse to do so and will die if they come into contact with the stuff) comes with a lot of extra wear and tear on the ol’ cell. So dealing with oxygen concentrations this high must involve some incredible cellular defense weaponry.

In addition, some of the embarassment of oxygen is believed to be tied up in clathrates — slushy mixtures of water and gas at the bottom of the lake. As you may imagine, popping the top on this baby could involve a reaction not unlike opening a 2-liter that has had a fun night with a paint mixer. More on that later.

Finally, although it is little-known today (I once had a senior scientist who shall remain nameless accuse me of making this up), Earth’s poles have on many occasions in its past — some quite recent — been lush and green. They were sub-tropical forests that somehow — I have no idea how — managed to survive three to six months of darkness each year. What subtropical forests and animals did under such circumstances is fascinating to think about. But we have abundant evidence of this — like petrified wood and tree mummies found on Axel Heiberg Island or more recently on Ellesmere Island in Canada (global warming is outing them). And here’s the thing: Lake Vostok was a lake before Antarctica was covered in ice. It was a lake during Antarctica’s Life o’ Riley. And its depths could well preserve evidence of that life, protected from the inexorable grinding crush of the overlying ice. WOW.

So there are many reasons to be excited about the exploration of Lake Vostok, provided we don’t somehow accidentally and catastrophically pollute or kill everything off by contaminating it with stuff from the surface. That, as always, is the trick. And it’s something scientists have been thinking about. How do you penetrate and explore such a place without destroying the very thing you came to study?

Good question.

Artist's conception of the drilling of Lake Vostok. For a more accurate view, visit the New Scientist article linked at the beginning of this post. Nicolle Rager-Fuller/NSF

The Russians have been working on this problem for well over a decade. Previous attempts to penetrate the lake were put on hold until Antarctica’s governing body could be satisfied they had a good plan in place to protect it. So the Russians halted with about 100 meters to go. As the wikipedia article mildly puts it:

This was to prevent contamination of the lake from the 60 ton column of freon and aviation fuel Russian scientists filled it with to prevent it from freezing over.

I gotta hand it to the Russians — no half measures for them*. Still, as may be imagined, a 60-ton column of freon and aviation fuel might not be the best way to introduce ourselves to the Lake Vostok locals. So they have a plan for this too.

According to New Scientist:

“Beginning late December, we will first use a mechanical drill and the usual kerosene-freon to reach 3725 metres. Then, a newly developed thermal drill head, using a clean silicon-oil fluid and equipped with a camera, will go through the last 20 to 30 metres of ice.”

Then, if all goes as planned, the lake will burst from its icy prison, freezing shortly into its trip up the borehole, plugging it. In theory, the borehole’s negative pressure should prevent any contamination from our end reaching their end. And then, sometime next year after the plug is good and frozen, we’ll bore into the newly frozen lake water. Our sample will be complete and the lake contamination free — we hope. Anyone who’s picked up a sci-fi novel (or a newspaper, for that matter) knows these things can go horribly wrong (for instance — let’s hope that ice-water boundary is not 20 to 30 meters higher than they think it is) — but to never look in the lake seems a mistake too. So bottom’s up, boys.

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*especially considering my solution to this problem would essentially be something like: get iron with really long cord. Set to “Linen”. Place on ice. Wait.

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