I also love the way natural patterns are repetitive*. Similar patterns pop up in the oddest places. Look at the Charter Oak on the Connecticut quarter

and you’re looking at the search pattern of a feeding plasmodial slime mold (a giant ameoboid eukaryote), Physarum polycephalum,

http://www.flickr.com/photos/randomtruth/ / CC BY-NC-SA 2.0

which sends out protoplasmic veins in all directions in search of its prey: bacteria, fungal spores, and other microbes.

Does math underlie that too?

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*I also love how this video was for his mom. : )

Efficiency in Motion: A wild slime mold clambers over soil and moss looking for bacteria and protists to eat. Note the dead leaf for scale. http://www.flickr.com/photos/deliciousblur/ / CC BY-NC 2.0 Not for commercial use.

Behold, the artful amoeba itself — a slime mold. In this case, it is Physarum polycephalum, the lab rat of plasmodial slimes. Scientists in Japan have been leading the world in creative slime mold research, demonstrating about 10 years ago (when I was first learning about these creatures) that slime molds could solve mazes. If you’ll recall, slime molds can also remember. We’re talking about an oversized bag of multinucleate cytoplasm here, folks. (Cytoplasm being, of course, everything inside a cell membrane, and multinucleate because it contains lots of nuclei, or DNA packets) So it was no surprise to me to see the latest juicy morsel of slime mold research last week, once again from Japan, showing that not only can slime molds efficiently design rail networks, they can do it for a budget comprised of a $2.99 box of oats. Planning engineers, prepare for Japanese outsourcing.

The slimes managed a decent reproduction of the actual Tokyo rail network when scientists put a piece of the mold where Tokyo would be inside a Japan-shaped corral with oat flakes placed at the location of major cities. To simulate mountains or other barriers that slime molds have no way of knowing about, they illuminated portions of the map. Slime molds, like vampires, trolls, and college students, hate light. In just over a day, the slime mold had taken in the lay of the land and laid down its solution to the problem. The similarities were striking. For a map of the actual Tokyo rail network versus a slime-mold-designed network, see here (scroll down).

Slimes do it by spreading out in all directions, moving on from areas without food and pumping more cytoplasm into the ones that do. For a great video of the slime mold doing its thing in the experiment, see here.

So you see, slime molds would never miss that left turn at Albuquerque. They’d take both turns. : ) Boringly, the scientists designed a computer program to replicate the effect that they hope could help design mobile and computer networks without human help. I don’t understand why they don’t just stick with slime molds, though. “Will work for oats — prefer nights” makes for a pretty attractive employee in my opinion.

By the way, the “oat flakes” they talk about in this study are just regular rolled oats. Though you might be tempted to think the slime molds are eating the oats, they are not. They eat the bacteria that live on the oats. Yes, your oats have bacteria on them. No, this is not cause for panic. In spite of what the makers of Chlorox would have you believe, germs are a normal part of our world. More on that another time . . .

To see how most slime molds fit in to their section of the tree of life, go here and look for “Amoebozoa”.

Slime mold sporangia (spore capsules) broken open and laid bare to the wind as nature intended. A few unopened capsules are on the left. Photo courtesy Mary Jane Howell.

At last, two actual slime molds! As hard as I searched, the best I could find were plenty of tiny white-spored objects (fungi) erupting from the wood. I learned slime mold spores tend not to be white. : ( But local slime mold expert Mary Jane Howell’s sharp eyes picked out two (not so slimy) slimes. One, a Stemonitis, often called “hair growing on wood” because of their long spore-making sacs called sporangia, had lost most of its spores and was fairly unexciting. Only the hairnet-like frame of the sporangium was left, and even that was a bit disarrayed.

But another, Perichaena corticalis (top photo), still showed the bottom half of its spherical spore capsules and a thin veneer of yellow spore dust.

I also learned there is a certain age of fallen log that is ideal for slimes — bark starting to come off, but not all off, and that looking underneath the log or bark can also bear fruit. To review, plasmodial slime molds start out as spores that hatch into amoebae or flagellated swimming swarm cells. The amoebae crawl around for a while feeding on bacteria and other microorganisms in the soil until they run into a mate.

After they fuse, they eventually start pumping out nuclei and more cytoplasm like crazy but everything stays in one big bag — the plasmodium — that crawls around until things dry out. They then produce the fruiting body, of which the spheres  of Perichaena above are one form.  When those dry out and crack open, the spores are distributed by the wind.

Fungi and slime molds aren’t the only thing I look for when I’m out. I also pay attention to lichens and plants, which have the indisputable advantage of being much more abundant and much less dependent on recent rain for viewing. I found a new (to me) species of bog or rein orchid (Platanthera sp.), pixie sticks and pixie cups (lichens, probably Cladonia sp.), and everywhere the jewel-like fiery red pendant berries of clasped-leaved twisted-stalk (Streptopus amplexifolius) of the lily family. Lilies are monocots, one of two major flowering plant divisions. These plants tend to have parallel veins and flower parts in threes — if you click on the link, notice the leaves with parallel veins and 6-petaled (tepaled, actually) flowers hanging from their twisted stalks.

Finally, we found, in turning over damp branches, several of these tiny snails. As you can see, they are plenty slimy, and plenty cute.

Do we have any invert experts here who can ID them? Here ends the tale of the slime mold hunt!

In yet another sign of what an incredibly big dork I am, I have arranged to go slime mold collecting with Rocky Mountain National Park’s volunteer slime mold expert. We will be going to an undisclosed mountainous location well outside the park. I am bringing my shockingly inadequate camera but if I find anything worth sharing, I will definitely post it here later this week! I need hardly add that it is still bolete and chanterelle season, so with any luck, I will have something for both brain and table. Happy Sunday . . .

Credit: George Shepherd. Used with permission; click image for link.

Striking, no? And strange as it may seem, neither one of these creatures was the inspiration for the Boston street “grid”. Those Bostonians thought that one up all on their own.

This would be, I believe, another form of our old friend convergent evolution. So what the heck are these two things? Well, the cover of Science is a closeup of a tropical coral called Favia speciosa. I believe the lacy network (scientists would call it “reticulated” or “reticulate”, which is just a fancy Latin term for “net-like”. Gladiators with tridents and nets were called “retiarii”) is the bony calcite skeleton of the coral, the walls between each individual animal or “polyp”. During the night (or whenever they get peckish), they poke their little heads out and filter feed the water with teeny, finger-like tentacles.

The second image is, of course, one of my favorite — and distinctly terrestrial — creatures: a pretzel slime mold, Hemitrichia serpula. This is one of those plasmodial slime molds I get so excited about that starts out as two individual and microscopic amoebae in the soil who meet, have coffee, realize they share the same values, desire for spores, and that all-important “chemistry”, and decide to fuse and grow into a giant, gelatinous, pulsating bag of cytoplasm that goes on an insane bacteria-eating rampage.

When the time has come for the blessed event, instead of making individual bulbous sporangia (places where spores are made) like the slime mold in the photo at the top of this page, H. serpula simply freezes into a netlike structure and subdivides its entire body into a giant spore mass. I believe this structure goes by the beautiful name “aethalium” (pronounced “ee-THAL-ium”. Should name first-born daughter “Aethalia”).

UPDATE 7/23/09: George Shepherd informs me that this reproductive structure is a plasmodiocarp, not an aethalium. I’m working on figuring out the difference between the two, but when I do I’ll post it here.

After drying out, the structure splits open and a fuzzy mass of spores flies out and blows away in the wind. In the photo above, you can see this is already starting to happen.

Back in May, I saw a call by a group of skeptics I belong to for talks at their annual meeting, the Colorado Skepticamp. The talks could be on any sort of skepticism OR on any discipline of science. One of my aims is to speak publicly and frequently on the sorts of things I blog about here, so I jumped at the chance. My idea was to do a quick survey of life on Earth hitting all the major groups in less than 30 minutes, so I called it (with apologies to Mel Brooks), “Life on Earth: The Short, Short Version.” So here you go — My 23 Minutes of Fame.

There are two versions. One has better sound:

And this version has higher resolution:

I made a few mistakes for which I hope you’ll forgive me. . . all I can say is this was my first time giving this presentation and it’s hard when your mouth is moving faster than your brain. I have noted them below. If, after watching it, any of you are interested in having me/hiring me as a speaker, I’d be happy to make it longer or shorter or elaborate on any taxon that interests you. : )

Errata/Clarifications

• I mentioned that Hennig changed the way we do taxonomy by suggesting evolution as our grounds for classification. What I forgot to mention is the way that evolutionary history has now become largely judged by DNA and not always so much by what the organisms look like, where they live, etc. The byzantine circular taxonomic trees I presented were created using DNA sequences – and molecular taxonomy now dominates classification (it’s not always the last word, but it’s almost always the opening sentence). But for all of our scientific efforts, judging the true evolutionary history — especially when different pieces of evidence conflict — can still be a bit of an art.
• The slide where I show some differences between bacteria and archaea shows a few of the differences between these groups, but there are many more. Don’t think by any means that these are the only two. I mentioned this earlier but not at this point.
• Flu viruses are in Orthomyxoviridae, not Paramyxoviridae. It’s the taxon directly above the one I point at. I was in the right neighborhood but again, the mouth was moving too fast for the brain. This is what happens when you try to cram life on Earth into 23 minutes.
• Operculum is Latin for a little lid or a cover, not Greek for cap. I knew what I meant, I just didn’t say it right.
• Moss spores are haploid, not diploid. Meiosis occurs in the the sporangium in the top of the sporophyte.
• I seem to imply all cup fungi shoot their spores in a cloud but that’s not accurate. Many cup fungi don’t. Even the ones that do may not if they’re not in the mood. In this respect, they aren’t so different from. . . er . . . never mind.
• I got a little confused on jellyfish but remembered soon after the talk what the problem is: jellyfish do not have alternation of generations in the same sense plants do. Both forms are diploid (the sperm and egg fuse before dividing further), but they do alternate between sexual and asexual organisms.
• And finally, I looked it up and Venus’s Girdles are indeed bioluminescent at night. Sorry.

Muchas gracias to Mile High Skeptics for making generously recording and sharing my lecture!

Many of you know about my slightly (ok, entirely) unnatural slime mold obsession. They’re weird, cool-looking, and semi-sentient. And they’re even here in Colorado! I found three or four different species when on the Mycoblitz in August up at Rocky Mountain National Park. They’ve even been used as robot brains. (see http://www.newscientist.com/article/dn8718)

A yellow slime mold at Olympic National Park.

Not bad for a giant crawling multinucleate bag of protoplasm. Well, here’s further proof of just how cool they are: http://discovermagazine.com/2009/jan/071

Even slime molds can remember.

So how on Earth is a feat like this possible for an organism that’s never even heard of a neuron? I’ll leave that for us to ponder. . . because no one really knows.