This is *not* the ninja slug, but if you imagine that seedpod is a katana, we're 90% of the way there. OK, maybe not. Creative Commons papalars. Click for link.

As the year rounds down, I wanted to point you in the direction of a nice gallery put together by the editors at National Geographic of 2010’s weirdest new animals.

My fave: the ninja slug of Borneo. Apparently these guys shoot calcium carbonate hormone-soaked “love darts” into their paramours. Somehow this increases reproductive fitness, though whether it does so by helping lady slugs make more eggs or by putting them more “in the mood”, if you know what I mean, Nat Geo does not say. The wikipedia page seems to imply love dart hormones increase sperm survival on the part of the shooter, and that the use of the darts is fairly widespread among land snails and slugs. As with so many invetebrate systems, I’m *really glad* this is not a part of human courtship. Do not miss the gallery of love dart photos and drawings at the bottom of the page — fascinating. On a related note, anyone who has not scene the epic snail love scene (complete with opera music) in “Microcosmos” is greatly missing out. The snails look like they’re having more fun than most humans. Run, do not walk.

Taxonomically, slugs are snails that lost their shells. Like lichenization, this turn of events has taken place many times in unrelated groups, so “slugs” are what taxonomists call “polyphyletic”, or not a true, valid taxonomic group (which should always be based on a single ancestor and its descendants — that is, a monophyletic group). There are even some slugs that are still in the process of losing their shells and carry a tiny shell too small to duck into on their back, rendering them “semi-slugs”. Slugs are gastropods, which are in turn molluscs. You can see how it all fits together and who else they’re related to here. That’s it for 2010! See you in the New Year!

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.

What mystery of the deep or meditation on life was I pondering so seriously before the dive? Even I can't remember. This photo is kind of growing on me. It reminds me of a Rembrandt. We can call it "The Night Dive". Photo by Jeff Leicher

Don’t I look serious? You’d think I was about to dive at night into 4,000 feet of shark-infested* waters. Actually, I have no idea what I was thinking at that moment, other than probably trying to quiet my mind and prepare myself mentally. As you can see, the lights of Kona are not far behind us, and quite comforting. As recounted in Wonderful Pelagic Things, which I’ve updated with some of these photos to reflect what I saw, dive in I did. Here is some of what we saw (all photos are by Jeff Leicher and/or the crew at Jack’s Diving Locker):

I’m not really sure what this was, although it does look squid-like. I don’t recall seeing this one personally. These photos are a bit deceptive in that in order to capture the animals on film, the camera underexposes the background. In real life, our lights lit the water a vivid blue, not black as it seems here.

Here’s one of the pros with their big expensive camera. This photo helps give you the feel for the sort of equipment needed to film in these conditions, and most definitely not affordable by me.  It should also help give you an idea for the size of most of these creatures relative to us.

Here is one of the ctenophores, or comb jellies, that we encountered. You may recall from my post that just as I started looking at one, it sucked up a tiny pink plankton for dinner. This may or may not be the one — I can’t tell if that thing in its gullet is it, but in my recollection, it was definitely bright pink.

No idea what this is, and I wasn’t fortunate enough to see it personally. Jeff has labeled it as a “quadropus”, presumably the four-tentacled cousin of an octopus, but according to wikipedia, that is a fantasy creature. Any marine biologists out there have any ideas?

This is the fantastic heteropod I missed, with what looks like a small squid or fish in the distance at the tip of its tail. These guys are phenomenally cool ex-mollusks (and I mean that in the same sense as ex-Marines) that have forsaken their snail shells to swim naked and free in the ocean like vicious little hippies. They look for the other pelagic creatures from which to take bites using their saw-like radulas at the tip of a Futurama-esque eye-stalk (but is not — the eyes are at its base). The larval forms still possess coiled mollusk shells, but they lose them when they become adults. They also possess a single “dorsal fin” — which is actually totally inaccurate because it is really ventral (stomach side — they swim “upside-down”) and was originally the mollusc’s foot —  which they undulate and paddle about with. For some reason, when moving, they remind me of Sir Hiss tooling about  in that ridiculous balloon at the tournament in the 1973 Disney “Robin Hood” (see 2:15 here). Some species possess a sucker on their “fin” which the heteropod no doubt uses to hold its prey still while it savages it alive.

And finally, we have the “alien pelagic peanut creature” whose identity I still have not confirmed (Egg mass? Gummy snack?) with a little shrimp hitching a ride. Still have no idea what the heck these are, but they sure look cool.  Any ideas, readers?

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*”shark-infested” intended humorously only. I love sharks as I love all ocean life — just as long as they’re not actively gnawing on/envenomating/ovipositing into me.

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. : )

It’s a whip scorpion, in the order Thelyphonida, although this one has sadly somehow lost its long thin tail, or “whip” (called technically, like those of protists and sperm, a flagellum — but they are *not* evolutionarily-related structures). This one seems to be very well fed, though thankfully not on Jen. I’m taking a short arachnology class at the Denver Museum of Nature and Science right now, and this was one of our subjects. According to my classmate, these animals, also commonly called vinegarroons because of the defensive acetic acid (vinegar) glands they possess near their tails, are the nerds of the arachnid world: “They just kind of bumble along, smelling like a salad.” Raptoral pedipalps (big scary pincers) aside, the one I held did seem to be a sweet, gentle creature. I’ve now held a whip scorpion! Yay!

I haven’t talked about arthropods at this blog much yet, and a paper published in Nature a few weeks ago together with my play date with Stumpy, above,  provide the perfect opportunity to correct that. This post is called “The Creepy-Crawly Branch of the Family Tree”, but it could equally well be called the Floaty-Swimmy Branch, or the Bloody-Sucky Branch or the Borey-Eggs-Iny-that-Hatchy-and-Devour-the-Insides-of-your-Hosty Branch. There are arthropods that do all these things. So let’s have a look at the broad shape of the tree as revealed by this new analysis of the evolutionary relationships among members of Arthropoda:

Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences Jerome C. Regier, Jeffrey W. Shultz, Andreas Zwick, April Hussey, Bernard Ball, Regina Wetzer, Joel W. Martin & Clifford W. Cunningham Nature 463, 1079-1083(25 February 2010) doi:10.1038/nature08742

Now there are a lot of scary words on this diagram, it’s true. But take heart! Look how many drawings of awesome creatures there are! And it’s way better than the alternative that most biologists have to deal with, which I also had to learn to read in school. Before I get to what’s new and cool about this tree, let’s talk a little bit about what trees like this are, and then about the main groups you see on it.

This tree is called a phylogeny, or phylogram (you also hear cladogram). It is a hypothesis of evolutionary history. That doesn’t mean scientists are hypothesizing that these creatures evolved. That’s a foregone conclusion. The hypothesis is what the specific relationships are between the different groups. In other words, the question is, “How is everyone related?”, and this tree is one possible answer. In some trees, as appears to be the case here, the branch lengths are proportional to the evolutionary distance between the different groups. That is, the longer the branches, the more evolvin’ that’s been going on. Evolution, in this case, is measured in DNA nucleotide changes. DNA, as you’ll recall, is made of many base pairs called nucleotides. There are four kinds. When one changes to another, that is called a point mutation. The more of these changes that build up, the greater the evolutionary distance between groups.

For this tree, scientists studied 62 genes in 75 arthropod species. They sequenced them all and compared the changes. They put all the data into a special computer program designed to figure out which sequences are most similar to which other sequences in the five-jillion possible combinations of relationships embodied by 62 genes in 75 species. Then they cranked the computers up to 11 and probably waited a few days (or maybe even weeks! I have heard stories of scientists locking computers in closets during this time) for them to churn out the solution to this hyper-space chess problem. The lone tree you see above is the result.

So what do we see? At the top is Hexapoda, which as you may guess are insects and friends — the six-legged among us. Below them you see an interesting group called Xenocarida. More on them later. Below that group are the Vericrustacea and Oligostraca, which are both, as far as I can tell, basically crustaceans. In both groups you see some old friends: the copepods (some freshwater species of which carry Guinea Worm larvae, a topic I covered in January), the ostracods (who we looked at in a post on deep-sea bioluminscent organisms last year), and the Decapoda, which has a high taxonomic tastiness index: it includes lobsters, crayfish, crabs, and shrimp.

Next are the myriapods: centipedes and millipedes. Below that are the chelicerates, or organisms with special mouthparts called chelicerae — sea spiders (pynogonids), horseshoe crabs, scorpions, ticks, mites, tarantulas, spiders, and Stumpy. And rounding out the base of the tree are the outgroups — the groups we use to “root” the tree, or give it a direction. They are usually the most closely related organisms not in the group of interest, here arthropods. In this case, they are the ridiculously cutely-named water bears or moss piglets — the tardigrades — and velvet worms, the onychophorans. Velvet worms are half of the subject of a crazy-*** theory that somehow got published last year hypothesizing that metamorphosing insects like butterflies were the result of an unholy chimerical union between velvet worms and a larva-less insect.

Also looming large in the arthropods but not on the tree simply for reasons of chronological discrimination (and also because, being extinct, we have no DNA to sample) are the the trilobites. According to my copy of Colin Tudge’s Variety of Life, they branched off somewhere between the Tardigrades and Chelicerates.

OK, so now that you’ve waded through all of that, what were the surprises in this new tree? Scientists also used to think millipedes and centipedes were closely related to insects. They’re both land arthropods, after all. My two college biology texts (published 1995 and 1996) show this relationship, though Tudge(2000) is agnostic on whether millipedes and centipedes or crustaceans are more closely related to Insects. Now it appears certain that, since all crustaceans are aquatic, insects and centipedes/millipedes represent a seperate evolutionary invasion of land by arthropods, much as seals and whales represent two seperate re-invasions of the sea by mammals.

This study also supports the hypothesis that insects evolved from a crustacean, which is why we can’t use the term “Crustacea” any more — the group as traditonally defined doesn’t include the insects, but this tree shows that it should (since the principles of modern evolution-based taxonomy require proper groups to include an ancestor and ALL of its descendants). The term “Reptiles” poses the same dilemma, because it should technically include  birds. So some scientists have stopped using that term as a taxonomic classification, too. Little-r reptiles is OK, though, as informal name for the group.

Finally, it appears hexapods’ (insects’) closest relatives are an obscure underwater-cave-dwelling group newly dubbed the Xenocarida. Carl Zimmer goes into that in admirable detail here.

But the take-home message of this tree for you is simple: look, admire, and marvel at the variety and abundance. In fact, I give you a homework assignment, should you choose to accept it: pick a group on that tree that looks interesting that you’ve never heard of before. Look it up. Find out what it is, what it does for a living, and where it directs its mail. You’ll be glad you did, I promise.

If you think this is bad, wait till you see the video. A scavenging nemertine worm, cousin of the famed "screaming eels". That fish on the left looks like it has suddenly realized it's headed for the fish stick factory. Photo by Henry Kaiser, National Science Foundation

In case you missed it in the last few weeks, BBC’s new “Life” series (narrated by the great D.A.!) released an amazing clip of a starfish and marine nemertine (aka ribbon) worm feeding frenzy in McMurdo Sound, Antarctica. They won’t allow video embedding, but go here for the superlarge youtube video in all its glory. Be warned that the seal noshing is a bit . . . graphic. If you imagine the seal made from the same stuff as gummy bears or laffy taffy, that might help a bit.

Here is another BBC article describing the video. When will we in the United States get to see “Life” in its full glory? Come on BBC, throw us a frickin’ bone. We still haven’t got “Creation” yet either, though word is it’s coming in January.

A brief perusal of the wikipedia article on nemertines reveals some compelling details; these worms have probosci that may have poisonous stylets used to attack and kill their prey. This little detail was a particular gem:

The proboscis is wrapped around the prey, which is normally other invertebrates such as crustaceans and annelids and can be many times larger than the nemertean itself, and the prey is then stabbed repeatedly with the stylet until dead.

Awwwwww. The article also sedately notes the worms are documented to reach 30 meters; some reports have indicated they may reach 50 or 60 meters. Ladies and gentlemen, that’s almost 180 feet. A blue whale reaches about 90 feet.

It seems these worms used to be thought of as closely related flatworms, like the cross-eyed Planaria of biology lab fame. Now scientists understand these worms are more complex than once thought, and more closely related to the annelid worms (which I’ve written about here before) and mollusks. Here’s a nice tree showing the relationship. And just look at all the weird, wonderful life on that tree! Have you even heard of half of those?

Finally, just to recap, I [heart] David Attenborough.

The man himself! How can I lure him to Colorado? Sadly, we have no birds-of-paradise. We have do have birds-of-ridiculous-mating-displays, though, aka sage grouse. Wildscreen's photograph of David Attenborough at ARKive's launch in Bristol, England © May 2003. Creative Commons Attribution License 2.5, click image for link.

I just watched the first half of Attenborough in Paradise the other night, and his seeming ability to casually drop Alfred Russel Wallace quotes and ad lib arresting narration is astounding. David, I salute you.

Isn’t it cute that they make a heart shape when they mate? It almost makes up for the fact the male has a penis from hell. Although it’s by no means the most frightening I’ve seen. There are many insects (of which bedbugs are a prime example) that mate by “traumatic insemination“, in which the male stabs the female with his often-horrible, spiky penis and injects sperm directly into the female’s body cavity. [Pause while female readers silently scream in horror.] Brought to you by the James Cameron School of Insect Adaptations Worthy of Sci-Fi Horror Flicks (TM).(Motto: “They mostly come out at night. Mostly.”)

In any case, notice that these are damselflies. Many people confuse them with dragonflies. Here is your natural history lesson for the day. This is a damselfly:

And this is a dragonfly:

Note the chief differences: Most damsels neatly fold their wings behind them when they land. Dragons hold them out like biplanes. Careful observers will also note that dragons’ wing pairs do not match as closely as damsel wings (the dragonflies’ hind wings tend to extend tailward farther) and damselfly eyes are much further separated. Almost googly, one might say.

Here’s a tree to show you how they’re related. Their clades’ (groups’) technical names are Zygoptera (damselflies) and Anisoptera (dragonflies). Notice that the uneven wings are right in dragonflies’ formal name: an-iso-ptera: “not — same — winged”.  They’re both in the insect order Odonata; back out via the little arrow on the left to see how they fit into the Insects.

Now you have to admit — that orange ostracod is even more amazing than the depth-charge wielding copepod. I mean come on! Had you ever imagined a creature like that could exist? Most ostracods are considerably smaller and are called seed shrimp because of their resemblance to something like a bell pepper seed. The males should get some sort of award for virility; many species have two penises and sperm that can be up to six times the male’s body length when fully uncoiled. The ostracod in this film appears to be  a female, given the clutch of round objects residing in its posterior.

The filmmakers here seem to subscribe to the Star Wars school of foley-artistry: no sound in space? No problem! We’ll just give the spaceships cool sounds anyway (good call). Bioluminescence is silent? No problem! We’ll just give flashing creatures Super Mario-grade sound effects . . .  No offense meant, though, Blue Planet dudes at BBC. I worship your work. Unlike Macgillivray Freeman, who in my opinion have largely squandered the IMAX format with their insultingly stupid and poorly written scripts, in spite of brilliant cinematography . . .

Annnnyway . . . .Copepods and Ostracods are actually fairly closely related, both being Crustaceans. Check out the copepod taxon here, but make sure to check out the next highest taxon, Crustacea, to see how copepods and ostracods fit into it. Jumping down the ostracod hole will take you here.