I have a new guest post up today over at the Scientific American Guest Blog on a newly discovered cache of the earliest known big multicellular life — and how some of it (but definitely not all) is startlingly like stuff alive today, 600 million years later. Go check it out!

Algae having a par-tay today. It's nothing compared to the 5-million year bender they went on 250 million years ago. Creative Commons eutrophication&hypoxia

About 250 million years ago in what is today the vast backwater of north central Siberia, the Earth coughed forth an unimaginable quantity of lava over the course of 1 million years. The liquid rock was a low-viscosity, thin stuff (for lava), so instead of forming a field of towering volcanoes it oozed out into endless plains. Covering some 1.5 million square kilometers today (600,000 square miles — something like the surface area of Europe), the beds may have originally covered 7 million square kilometers and taken up 1 to 4 million cubic kilometers in volume.

Scientists still do not agree why this happened, although it has happened many times before and since around the world. But they do agree on the timing: it happened at the same time as the Great Dying — during the Permo-Triassic extinction just prior to the age of dinosaurs that wiped out more life on Earth than any other, including the one with the giant asteroid with our name on it.

Not all scientists agree that the Siberan Traps, as they are called (trap comes from the Swedish word for “stairs”, which is how the frozen lavas can appear today) chiefly caused the extinctions. But many do, and it seems to be solidifying (er, pardon the pun) as the majority opinion.

What is also known is that life took some time to recover from this cataclysm. For at least 5 million years after, we can find little in the fossil record. Scientists have wondered whether this was a case of too much or too little food.

How, you might ask, could too much be a problem? Well, visit your nearest pond contaminated by fertilizers from lawns, golf courses, or farms and you will see: vast swarms of algae, that hog all the oxygen and choke out “higher” forms of life like fish. Or, for that matter, the New-Jersey-sized Dead Zone in the Gulf of Mexico, which formed in response to the endless streams of fertilizer runoff from farms pumped into the sea by the Missouri, Mississippi, and Ohio River system. We call this eutrophication*, and now, the authors of a paper in in Earth and Planetary Science Letters are pretty sure it is what prevented most life from recovering for those five million long years.

What happens when the party gets a little too wild. A lake in China with rampant eutrophication. Creative Commons eutrophication&hypoxia

How might scientists figure this out? As it turns out, one of the enzymes that catalyzes photosynthesis has a quirk. Thinking back to high-school chemistry, recall that the nucleus of an atom is made of protons and neutrons. Different elements are defined by the number of protons their nuclei contain. Carbon *always* has six protons. If it had seven, it would be nitrogen. But elements can vary in the number of neutrons they have. Carbon, for instance, can commonly have six neutrons or seven. Carbon-12 represents the former, while carbon-13 the latter.

As it happens, one of the chief enzymes of photosynthesis — RuBisCO, the one responsible for grabbing carbon dioxide from air and setting it on the path to become glucose — processes carbon dioxide containing carbon-12 a little faster than carbon dioxide containing carbon-13. Over jillions of cycles, the difference accumulates, and life becomes enriched in carbon-12. It makes little or no difference to the organisms themselves.

But it makes a big difference to scientists, who can use this knowledge to tell how fast the oceanic biological pump — the transfer of carbon from the atmosphere and surface waters to the seabed by microorganisms that live, die, and sink — is churning. The more these microbes nom, the more carbon-12 builds up in preference to carbon-13 in seabed deposits, where marine algae sink, store carbon, and are eventually pressed into limestone after they die. Scientists who studied marine deposits recorded in Chinese rocks during this 5-million year gap have found the carbon-12 enrichment is about double what exists today. If life had starved after the Traps did their dirty work, they would expect to see the opposite.

This is the scenario the authors of this new paper believe may have happened: as they erupted, the Siberian Trap lavas and the rocks they metamorphosed by contact spewed carbon dioxide (as well as many other volcanic gases) into the atmosphere. This warmed the atmosphere, which increased the evaporation of water, itself a greenhouse gas, perpetuating the cycle.

At the same time, more water vapor produced more rain, which weathered the land quickly. All that runoff drove incredible quantities of phosphate — a nutrient that limits the rate at which marine algae can grow — into the ocean. With a new all-you-can-eat buffet of phosphate and carbon dioxide at their disposal, marine microbes went nuts. The ocean was stripped of free oxygen, preventing any animal life that had managed to survive the extinction itself from regaining ground. Once the initial trauma of the Permo-Triassic extinction was over, these algae must have bloomed in quantities unimaginable. What is now the Blue Planet, and once may have been the White Planet, was briefly, it seems, the Green Planet.

What finally stopped the madness (from our perspective as vertebrates), was the waning of the volcanoes. Eventually, carbon dioxide levels dropped, and warming and rainfall decreased. With less erosion, oceanic phosphate and nitrogen concentrations dropped. Without enough of these nutrients to go around, algal numbers shrank, leaving enough oxygen around for other forms of life to exploit. And, luckily for us, they did.
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* Which is the reason you should all be using phosphate-free detergents.

Meyer, K., Yu, M., Jost, A., Kelley, B., & Payne, J. (2011). δ13C evidence that high primary productivity delayed recovery from end-Permian mass extinction Earth and Planetary Science Letters, 302 (3-4), 378-384 DOI: 10.1016/j.epsl.2010.12.033

I would like a fascinator made in this shape. The dinoflagellate Oxyrrhis marina with its transverse and longitudinal flagella. Creative Commons Census of Marine Life E&O

Life on Earth is full of weird convergences. For example, the cell walls of fungi are made of chitin, as are the shells of insects and arthropods like lobsters and crabs. Why? Whether due to chance or something deeper, I have never heard a good explanation.

Similarly, the proteins called rhodopsins are found in two seemingly completely unrelated places: the retina of your (and all vertebrate) eyes, and in some photosynthetic archaea and bacteria. We use ours for detecting light (it’s in the rod cells used for low-light vision); they use theirs to pump protons (as illustrated and discussed recently here) to make food.

And now, scientists have discovered a predatory dinoflagellate that has apparently stolen a bacterial photorhodopsin from one of its meals — and is using it (see also here).

The protein in question is called rhodopsin (Greek root “rhodo” = rose and “opsis” = sight) because it absorbs blue-green light and so appears purplish-red. Rhodopsins have seven protein coils called alpha helices that pass through membranes the protein is embedded in. In turn, embedded inside the helices is retinal, a light-sensitive pigment. As a result, the whole structure changes shape in response to light. In vertebrates, rhodopsin has another subunit called a “G protein“. G protein acts as signal transducer, or on-off switch in a signaling cascade — just like a switch in an electrical circuit. Vertebrates use it to relay information to the brain about what the eyes are seeing. Bacteria use their rhodopsin simply for pumping protons, not for signalling, so they have no need for G protein section.

The bacterial protein — still seven alpha helices and a retinal — resembles overall shape of vertebrate protein, so scientists suspect they may be distantly related. Proteorhodopsin — the bacterial version, was only discovered in 2000, but the (now ironically named) bacteriorhodpsin found in archaea was discovered much earlier, in archaea living and photosynthesising in sun-drenched salt flats, brackish pools, or salt marshes.

The dinoflagellate Oxyrrhis marina (ox-EE-ris MARE-i-na, I think) is neither a vertebrate nor a prokaryote (bacterium/archaeon). And yet O. marina makes so much rhodopsin it has turned pink. How? Scientists believe the gene for the proteorhodopsin was acquired by what biologists call horizontal gene transfer — that is, O. marina was happily digesting its photosynthetic bacterial prey when the gene for this protein somehow wandered off and found its way into the nucleus (where DNA is stored) and slipped, spliced, or got sliced into the chromosome.

This appears to be a case of “hedging your bets” because O. marina is now both photosynthetic and predatory. So in this case, you can make your own cake and stalk it too. Scientists believe they use this protein not only to make energy by pumping protons and passing them back down a chemical gradient via an ATP synthase, but also to help digest the very prey they stole it from. As they say, all too easy.

But before I say more, a few words on what dinoflagellates are are in order.

The dinoflagellate Ceratium longipes, in all it's tricorne glory. One, and possibly two flagella visible. Creative Commons Census of Marine Life E&O

In short, dinoflagellates are two-tailed plankton. They are also protists, the loose association of single-celled organisms with DNA inside nuclei and cellular organelles that are usually much bigger than bacteria or archaea. About half are predatory, half make their own food, and obviously, now we know some do both. The photosynthetic lot are the second most abundant constituent of the photosynthetic marine plankton after diatoms (which I covered here).

Dinoflagellates (from the roots for “whirling whip”) are also alveolates like ciliates (including the paramecia I wrote about here) and apicomplexans (which include Plasmodium, the protist that causes malaria). That means they often have sacs called alveoli under their cell membranes, trichocysts (defensive spikes that shoot out like harpoons), and tubular mitochondrial folds, or cristae. Some even produce structures like the nematocysts of jellyfish. You can explore how dinoflagellates fit into the life family tree here (use the black arrows to move toward the root).

Some dinoflagellates cause the poisonous red tides infamous for sickening fish and swimmers alike. Others build up in tropical fish or shellfish and cause ciguatoxin or paralytic shellfish poisoning in people. Others become the zooxanthellae, the green algal symbionts found in coral and other animals and protists. These photosynthetic dinoflagellates vastly increase the speed at which corals can build their skeletons. And finally, some dinoflagellates (including some red tiders) are bioluminescent, emitting short flashes of light when disturbed, and are responsible for the unearthly glow of the wakes of ships passing through tropical waters in the night.

Bioluminescent red tide dinoflagellates getting all bright and bothered by rolling surf. Creative Commons Catalano82. Click for link.

Dinoflagellates have some interesting quirks; their chromosomes stay condensed throughout the cell cycle and down relax into a spaghetti pile of chromatin (individual DNA threads) between cell divisions. And they don’t wrap their DNA around proteins called histones as most of the rest of us upstanding eukaryotes do. They prefer instead to attach it to the inside of the nuclear membrane. Also, they tend to eschew the reliable DNA base thymine in favor of the boutique 5-hydroxymethyluracil.

My plans to take over my neighborhood swimming pool are now complete . . . Dinoflagellate blueprints. Creative Coimmons Shazz. Click image for link.

Their two flagella — which emerge from the same point — are often set in grooves. One is a belt-like transverse groove called the cingulum, and the other is a longitudinal groove called the sulcus. You can see those grooves in a beautiful scanning electron micrograph here. (See also here and here for a dinoflagellate that I swear resembles Baron Harkonnen in his fat suspensor suit). The flagellum set in the cingulum wraps all the way around, while that set in the sulcus trails off the back like a rudder. Strangely, the transverse flagellum is responsible for most of the forward motion and is what sets dinoflagellates whirling, while the longitudinal chiefly helps steer.

Dinoflagellates are also really good at engulfing photosynthetic organisms and endosymbi-izing them. Most of their chloroplasts have three membranes, suggesting they came from an ingested alga, not a bacterium, and are the result of a secondary engulfment, or endosymbiosis. Others have chloroplasts of different color, shape and form, some still with nuclei. Thus we can infer that dinoflagellates are really good at finding themselves new photosynthetic dates by hook or crook — definitely crook, in the case of Oxyrrhis.

Flexibility and Finding a way seem to be themes with dinoflagellates. O. marina, for example, is common in shallow tide pools around world; it will go so far as to cannibalize its own species if it comes to it and can take down prey almost as big as it is. Photosynthesis. . . hunting . . . cannibalism — this thing is the MacGyver of protists. It’s going to survive with whatever comes to hand. So if you’re ever doing O. marina research, please do us all a favor: do not keep bubble gum, paper clips, or high explosives anywhere near your experimental organisms. Thank you.

He has thus partially granted my wish from last year, and even plans to use the missions for science as well as exploration and adventure. . . but Richard, we’re only half-way there! Once you’re done planting Virgin Oceanic flags all over the seabed, please build a commercial version of this baby to take the rest of us down there! I’m willing to pay as much as the projected lowball cost to the space cadets going up on Space Ship Two — and this ride doesn’t even require escaping any pesky gravity wells via loads of expensive, atmosphere-heating rocket fuel. Have I sold you yet? Fingers crossed.

Here’s a similar plea from Dr. M over at Deep Sea News, although it looks like, sadly for him, the current model is a one-seater.

A graptolite sampler, from an ancient Encyclopedia Britannica

Occasionally, life looks like it isn’t. In the eastern forests of North America and in a thin strip along the Pacific Northwest (but sadly not in Colorado), hidden in plain sight on tree trunks you can find the gracefully named elven script lichen, Graphis scripta. With a little imagination, the lichen looks like secret writing, not like an eruptive fungal-algal symbiont that specializes in cohabiting in tree bark.

In the 18th century, Linnaeus, the father of taxonomy, faced a similar biological dilemma. He found patterns in rock he suspected were chemical or geological formations that looked as if they had been alive, but actually had not. He called them “graptolites” (= rock writing), and gave the name to a variety of things may or may not have been alive. Over time, however, the term was co-opted by paleontologists for a group of strange fossils that very much had been alive. The only problem was, no one knew what the living parts of these things actually looked like — or how they might be related to anything alive today.

At left, you can see a variety of these creatures’s tube-like houses, called coenecia (se-nee-see-a), which are found abundantly through marine rocks from the Ordovician, Silurian, and part of the Devonian. Some were branched and tree like (dendritic, see13, 18, and 27, left) and probably bottom-dwellers, and others took on a variety of other bizarre forms that scientists interpret as the products of a planktonic form.

Many tended to have characteristic “hacksaw” shapes (see 4a, 7, 15, and 19, left) either in tuning forks, or coiled up in spirals like watch springs, as if something had poked out of the teeth lining these tubes. But no one knew what. The few cases where some actual ex-animal had fossilized were apparently more like ex-animal smudges than ex-animal fossils.

The pterobranch Rhabdopleura, in a lovely study in blue and gold. Note the tentaculate feeding/breathing prongs, aka lophophores.

Meanwhile, in another part of the science universe, scientists were describing and identifying members of a group called pterobranchs (= winged or feathered gills). Stretching little more than a centimeter long and living in proteinaceous* banded tubes cooperatively secreted by their shield-shaped probosci, they humbly go about their business stretching their ciliated tentaculate arms (which may remind you of bryozoans’lophophores, which they merely resemble convergently because that’s what they probably are (see comments)) into the water currents to catch prey and exchange gases. Inside their proboscis is a true lined body cavity, or coelom (seel-um). They sometimes live on their own, but usually grow in colonies connected by stems, or stolons**, in that colony of fused tubes called the coenecium. Some species have a pair of gill slits, just like fish (For a nice look at the general structure, see here, here, or, yes, the plush version here).

And this may very well reflect pterobranchs’ position in the shrub of life. Pterobranchs, it turns out, are hemichordates, in the same group as the acorn worms (enteropneusts) I described here last year. They are animals that evolved from animals just on the verge of becoming chordates, or nerve-corded animals like ourselves. They have a tripartite body plan of proboscis, collar (whence the tentaculate arms spring), and trunk. Like echinoderms (seastars, etc.) and chordates (us, etc.) they have a complete digestive tract whose mouth forms from the second indentation in the hollow ball of cells formed after a fertilized egg starts dividing (= deuterostome). Like echinoderms (but unlike chordates), they have no body segmentation and a special kind of larva called a dipleurula (chordates have no larvae). Signficantly, a hollow neural tube grows in some species early in development.

Most suggestively, pterobranchs and the fossil graptolites seemed suspicously similar, although little more than two dozen species of pterobranch live today, and for millions of years in the Paleozoic (from the Cambrian to the middle of the Devonian), graptolites were the dominant zooplankton in the world’s oceans. Tantalizingly, the microstructure of graptolite fossil tubes is very similar to the microstructure of pterobranchs, a detail discovered when electron microscopes first peered inside tubes of both animals and ex-animals in the 1970s. But no preserved fossil animal could confirm this.

Looks like a graptolite. Quacks like a graptolite. Could be a graptolite. Wouldn’t it be great if we had some soft tissues preserved in a graptolite fossil! Well, now we do.

Galeaplumosus, which was probably a two-armed model. The right arm is broken off, but two tentacles are still visible on it. "You don't look a day over 500 million years. You and Rhabdopleura could be sisters!" From Hou et al., Current Biology. Click for link.

In a March paper in Current Biology, scientists report the discovery of a tentaculate graptolite 525 million years old from the lower (early) Cambrian.

Finally, in all its glory, an animal poking out of a conical graptolite tube. And what an animal!For pterobranchs, they are, at shy of two inches (four centimeters), Yao-Ming-class. Which is fitting, because the fossil was found in China and dubbed Galeaplumosus abilus, from galea (helmet) and plumosus (feathered), and ab (away from) and nubilus (cloudy). Yunnan, where the fossil was found, means “south of the clouds”.

The fossil provides the clincher on graptolites’ true identities: a banded (probably secreted) cooperatively-made tube with contractile stalk and tentaculate feeding arms projecting from the opening is the M.O. of extant pterobranchs.

Looking carefully at the fossil, scientists were even able to discern possible cilia (silly-uh — little hairs that beat back and forth to draw in particles of food) on one tentacle, and a possible contractile stalk inside the shell. What scientists have, apparently, is the earliest, largest hemichordate animal (zooid) ever found, alive or dead, and it seems to show that their way of feeding and building a house have changed virtually not-at-all in 525 million years. Take that, sharks***.

The authors of the paper hypothesized that the rarity of specimens like this is probably a result of most graptolites’ planktonic lifestyle: on the long trip to the big sleep, most graptolites/pterobranchs probably decayed before they hit bottom, while the shell has proved decay-resistant in modern tests. That this animal was preserved, they suggest, means it was likely a bottom-dweller.

And that would fit with what we know about graptolite natural history. Scientists long suspected that the first graptolites, which tended to be tree-shaped (dendritic) and evolved in the Cambrian, were likely sessile bottom dwellers. Only later, in the next era, the Ordovician, did a floating planktonic form also emerge, the Earth’s first large zooplankton — and by far the dominant plankton of the early Paleozoic oceans. With their collaborative approach to constructing a floating colony, they were a bit like floating bee hives or wasp nests, if the wasps were all attached at the abodomen by stems, secreted their own cells (instead of building them from chewed up wood or mud), and never left the nest. Like the vast floating chains of colonial salps in today’s oceans (though much smaller), they must have been strange indeed.

The graptolite Pendeograptus fruticosus from the Lower Ordovician (477-474 mya) near Bendigo, Victoria, Australia. This style is referred to as the "tuning fork".

These planktonic co-ops evolved so abundantly and so quickly that they are commonly used as “index fossils” by the geology and petroleum geology sets to date rocks relative to each other with fine detail. In their heyday, thousands of species filled the oceans, common, widespread, quickly evolving and easily identifiable: a rock dater’s dream (errr . . . yeah. Ammonites have also been used this way.) In the Silurian, for instance, 40 different graptolite zones have been described, with an average duration of .7 million years — incredibly fine detail for geologic time, where dating anything to within a few tens of millions of years is usually considered spectacular.

Sadly, the planktonic graptolites went extinct in the middle Devonian, about 380-400 million years ago. Thus, the first (Galeaplumosus et al.) and last forms we find in the fossil record (from the mid-Cretaceous, near the end of the age of non-avian dinosaurs) are bottom-dwelling dendritic forms — as are the handful of species alive today, the humble survivors of a formerly world-dominating group****. But let us take the sunnier view. This post could have been titled “Graptolites Are Not Extinct!”.

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To learn more about graptolites and pterobranchs, see here, and a nice page here by the British and Irish Graptolite Group (BIG-G : ) ).

*made of a collagen-esque material, a family of animal proteins that help keep your muscles attached to your bones and your skin perky.

**A term for horizontal connections between organisms. Stolon, incidentally, is also the term botanists use for stems (*not* roots) that run along or jut below the ground from plant to plant (aka runners). If you’ve grown strawberries you have experienced this phenomenon.

***420-million year-old posers

**** much like brachiopods

Hou XG, Aldridge RJ, Siveter DJ, Siveter DJ, Williams M, Zalasiewicz J, & Ma XY (2011). An Early Cambrian Hemichordate Zooid. Current biology : CB PMID: 21439828

I missed Edith Widder’s TED talk on ocean bioluminescence when it came out in 2010. Had I known, you would have been seeing this much sooner. It clocks in at 17 minutes, but don’t let that intimidate you; it speeds by. There’s a little something here for the biophiles, engineers, and daring explorers in all of us.

For a high-res version of this video, click here.

What I would have given to have been in that Wasp suit when she turned the lights out.

That jellyfish burglar alarm is just fantastically beautiful. Notice how the pattern is slightly different with each rotation. Why does it remind me of an ’80s electronic toy?

For the record, I am so with Edith on the whole, “When someone offers you a trip to the deep sea, you say YES.” In fact, I’m actively looking for a low-budget ticket to several thousand clicks down; it’s a dream of mine. I’m no Dennis Tito, but I can write. If you know someone traveling to the deep sea who might be in need of a science writer specializing in biodiversity and natural history who doesn’t eat much and fits conveniently in most overhead bins (5’2″, 108 lb.), LET ME KNOW.  : )

For a more in-depth look at deep sea life which Dr. Widder helped work on, see the Deep Sea episode of Blue Planet, available through netflix in the US (and mercifully narrated by David Attenborough, and not Oprah). You will not regret it.

Seawater is a soup of incredibly gorgeous and intricate creatures with sometimes titillating, baroque, or improbable lifestyles. And as it turns out, part of what’s in that soup is these guys. These three cuties are all crab larvae — from left to right, the zoea larva of the spider crab Maja squinado, the angular crab Goneplax rhomboides, and the thumbnail crab Thia scutellata. Mr.(Ms.) Thia looks like the adorable spawn of something you’d find torturing St. Anthony or in a Hieronymus Bosch painting (or both).

Regardless, they are way cute, and if you can believe it, said fellow(gal) at right will one day (predation permitting) turn into this. As Dr. Kirby points out, many crabs, mussels, barnacles and worms that live on the sea floor as adults send their larvae out into the plankton to feed, grow, and drift on currents to new homes. This works great if your offspring are legion and can therefore withstand the blistering assault of predators mining the plankton for food.

These beautiful photographs are the works of Dr. Richard Kirby, whose work I highlighted earlier this year here. He has put together a collection of plankton that reminded him of Christmas. So since I have done zero holiday decorating at home, I’ll spruce up the blog a bit with photographs Dr. Kirby kindly gave me permission to reproduce.

Here are “Five Gold Rings” — spiral chains of the diatom Eucampia zodiacus. Notice the gorgeous, lacy details of the spans, which are gold because there are tiny symbiotic photosynthetic phytoplankton inside called zooxanthellae.

And here’s one other favorite, the protozoan Acantharea.

I have covered diatoms before here, but not Acantharea or their larger group. Though Kirby compares them to fireworks, I see ornaments, which you can see too in Ernst Haeckel’s predictably gorgeous print here. They are radiolarians, amoeboid (yay!) protozoa that make intricate mineral skeletons. Acantharea‘s are somewhat improbably made of strontium sulfate — the mineral celestine, in keeping with our holiday theme — of all things. The acanthareans are currently classifed (probably not for long, as soon as the molecular people get their hands on them*) by their spine arrangement in a complex, and somewhat sadistic fashion that only a geometer could love.

For the full 12 Days of Plankton, go see a nice article with all the photos in the Daily Mail here, or a composite of slides here. He has just published a book of his photographs with descriptions, which I have not laid hands on or looked in yet, so cannot yet vouch for, called “Ocean Drifters: A secret world beneath the waves“. Though I cannot vouch for the book, I can definitely vouch for the subject.

I’ll have a few more posts before the 25th, but until then, early Merry Holidays.

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*Molecular people will classify them based on their relatedness as shown by DNA studies, not their outward appearance. Sometimes outward appearance is an accurate gauge of true relatedness, and sometimes you end up with whale and fish (aka convergent evolution).

Although I have to admit I was cheering for the worm at the end of this video. Come on, little squidworm! Evade that vacuum tube! I have no idea why. I’m all for science.

As you can see, the key feature of the squidworm are its voluptuous tentacles. You can get a much better look at them here. According to my admittedly scanty sources, the squidworm lives in the deep (ca. 10,000 feet, or nearly two miles down) and feeds on marine snow, a mixture of fish poop and dead plankton. I’m glad I don’t have to eat marine snow. I have to imagine it has the taste and consistency of that gruel from The Matrix . . .

What is unclear is whether they use those tentacles to grab their food, although I would imagine that is the case because most tenatculated organisms do. (UPDATE: According to information here, eight of its tentacles are used for breathing (gas exchange of CO2 and O2 by increasing the surface area for it) and the two that are loosely coiled in this picture are indeed for feeding. I don’t count eight of the other tentacles in the picture, but if the scientists say so. . . )  In any case, recall that polychaetes as  a group are characterized by lateral body extensions called parapodia (what look like their feet) that have bristly extensions called chaete (“kee-tee”), hence the name polychaete for the group. Polychaetes come in a vareity of splendiferous forms, including the christmas tree worm, the Pompeii worm, the recently discovered Osedax whale-bone-boring worm, and the Methuselah-esque (life expectancy: something like 250 years) cold methane seep tube worm Lamellibrachia. Polychaetes, in turn, are annelid (segmented) worms, like our old friend the earthworm. You can see how everyone is related (sort of — science in progress) here.

The squidworm stands out among polychaetes in a few ways: it is free-swimming, while most are tunnelers of the sea floor. It also has six pairs of oppositely branched nuchal organs — cilia-lined structures typically found in pits and used for smelling or sensing things. I’m not sure where those are located in the pictures. And its got those tentacles, which are as long or longer than its body.

Finally, the squidworm was discovered in the Celebes Sea. Where is the Celebes Sea? you may be wondering. GOOD QUESTION. I did not know either, so I looked it up. It’s in southeast Asia, just to the south of the Philippines and sorta midway between Australia and Vietnam.

And now you know.

Part praying mantis, part flatworm, part geminating snuffleupagus: Model of Anomalocaris from the Natural History Museum, London. Creative Commons Gaetan Lee.

On the list of hallucinatory animals, the Cambrian creation known as Anomalocaris has held a particular grasp on natural history buffs’ imagination. Its name (essentially “weirdo shrimp”), its fascinating path to discovery, and its use as a Cambrian fall guy in Burgess Shale recreations have all contributed to this. Natural history documentaries, in particular, have tended to portray this thing patrolling the Cambrian oceans and harassing helpless trilobites with the cool assurance of a Great White Shark. In my copy of “Prehistoric Life: The Definitive Visual History of Life on Earth” published by DK just last year (and highly recommended), the caption of the beautiful full-color page describing Anomalocaris declares “3 ft 3 in The length of the largest Anolmalocaris specimens. Its size and formidable mouthparts made it a top predator of the Cambrian seas.”

Before I come to the current study, it’s worth knowing something about the history of this thing. In the world of Cambrian paleontology, Anomalocaris is a superstar. Life’s first big multicellular experiment (that we know about) — the Ediacaran — was mostly about soft-bodied life. Its second great multicellular experiment is the one that gave rise to most of the major groups we recognize today. This was the community of organisms famously discovered in the Canadian Burgess Shale, and it is the one in which Anomalocaris was found. The only problem was that when scientists first found it, they thought they had three separate living things — a real life enactment of the story of the blind men and the elephant.

First found was a shrimp’s tail — but only the tail. It was this that was named Anomalocaris.

A proboscis of Anomalocaris. On first glance, they thought it was a weird shrimp because its little "appendages" were not jointed, unlike modern shrimp. As it turns out, it was a weirdo shrimp because it wasn't a shrimp.

Next found was a pineapple ring — or what looked like a pineapple ring. Captain Morgan notwithstanding, scientists interpreted this as a squashed jellyfish and named it Peytoia. Finally, scientists found a fossil they judged to be a sponge, and named it Laggania. The pineapple ring was attached, but was interpreted as a jelly fish that had just happened to settle on top of the sponge and got squashed into place. Finally, the scientist Harry Whittington at last found a fossil in which the shrimp hinder was attached to the pineapple ring. No, really? What the heck was this thing? A few years later, they put it all together: the sponge was the body, the pineapple ring the mouth, and the cocktail shrimp was one of a pair of probosci of this titanically large (for the Cambrian) animal. Anomalocaris, they called it, since earliest taxonomic names have precedence, and judged it to be the terror of the Burgess Shale fauna.

For the Cambrian, this thing was big. At about one meter (three feet) it dwarfed the other species we typically find in the ecosystem. But it turns out that titanism may have been the size enhancement that comes with being a whale shark, not a white shark. Scientists at the Denver Museum of Nature and Science conducted computer studies of Anomalocaris‘s bizarre mouthparts and found that it was extremely unlikely it was capable of crushing much more than a gummy bear, much less an armor-plated trilobite. Supporting their study, they examined some 400 fossil Anomalocaris mouthparts — and found nary a chip or scratch. Considering how soft our fingernails are and how frequently they get chipped or scratched, I’m afraid it appears Anomalocaris must have been chowing down on something either very soft or tiny indeed. Soft worms, they suggest — or plankton.

So the vicious predator may have been a gentle, harmless (unless you happen to be a plankter) filter feeder. At least — that’s the tale now! With as many twists and turns as this story has taken, I wouldn’t be surprised if another surprise lies in wait. For instance . . . scientists have actually found and identified fecal pellets of this thing. That’s one study I, for one, will be glad not to have to do . . .

I've used this joke before but I just can't resist. . . "Luke, I am your father!" The ctenophore (comb jelly) Mnemiopsis leidyi. Creative Commons Steven G. Johnson

Remember comb jellies? The awesomely awesome spacecraft-shaped transparent oceanic stealth predators? I did a post about their general biology for Halloween last year.

When I was in Hawaii last April on my amazing pelagic night dive, I observed two comb jelly behaviors that totally startled me: just as I turned to look at one, it abruptly sucked a pink krill into its transparent stomach. (I’m glad I can’t watch *you* digest your lunch) And shortly after, it swam off under its own jet power, sucking in water and shooting it out through its muscular lobes. From watching the docile specimens found in aquaria — which never so much as lifted a lobe to exert themselves under their own power — I falsely assumed they were incapable of moving anything other than their cilia. But as it turns out, moving their cilia may be more than enough to lure the unsuspecting microscopic contents of entire seas to their doom. And “stealth predators” seems to be an understatement.

The species Mnemiopsis leidyi, originally native to the western Atlantic, but coming to a soon-to-be formerly pristine body of water near you (courtesy ship ballast water), is able to use its cilia to create a current of water fast enough to deliver its food to its mouth, but not so fast as to alert the unsuspecting foodstuff that it is . . . well. . . future foodstuff. Sneaky. Very sneaky. This according to a recent paper in the Proceedings of the National Academy of Sciences.

Understanding this ability may be greatly helpful in understanding how M. leidyi nearly emptied out the krill and small fish populations of the Black and Caspian Seas in the late 1980s and is well on its way to repeating the feat in the Baltic. Mnemiopsis was introduced into an overfished and polluted Black Sea in the 1980s, where it capitalized on struggling fish stocks to reach more than 10 animals per cubic foot in some places by 1989. The comb jelly ate the small fry of commercial fish like anchovy, causing a further drop in fish populations. Since then, the collapse of Black Sea fisheries, the decrease in pollution caused by the collapse of the Soviet Union, and the accidental introduction of another invasive comb jelly that preys on Mnemiopsis have curtailed its numbers somewhat. But lately the hardy jelly has also wreaked havoc in Israel, where gelatinous blooms gummed up the filters of a desalination plant, stanching a third of its 100 million liter daily flow; in the Caspian Sea, where it was introduced in 1999 and depleted 75% of the zooplankton;in the North Sea and western Baltic, which the comb jelly found its way into by hook or crook in 2006; and in the Mediterranean waters off Italy where it was first sighted just last year, causing local fisteries experts to fear for their stocks.

Though, as wikipedia calls it, this tentaculate ctenophore (say that 10 times fast) seems to be slowly taking over world waters (as are many jellies in the vacuum left by overfishing), that does not take away from its extraordinary ability to earn its daily bread in the same way you can cook a frog human(see comments : ) ) not by throwing it in a pot of boiling water, but by putting it in cold water and slowly turning up the heat. And though I’ve never seen one do its stuff in person (I was in the North Pacific when I saw my comb jelly, where this ctenophore species does not yet seem to have reached), I’m sure I’d still be excited if I did. Just as rock snot is destructive and ugly macroscopically but gorgeous up close, were one to look up close at the teeming ctenophore hordes that are doing so much damage to the fish stocks of Europe, one would find their cilia twinkle in the light, and, delightfully, glow blue green in the dark when disturbed. Coooooool.