Avatar's 'Walking with hexapods' or 'Don't walk this way'

I guess everyone will have seen Avatar by now. If you haven't, and if you like speculative biology, go out and see it now. You can read this post before you go, as it will not spoil the storyline. The film is an amazing spectacle. I loved it, and was fascinated by the computer generated graphics. There is a short 'featurette' in the form of a short documentary on the internet that you should all watch, because it explains some of the basic tenets of the film. Here it is, but remember that there is a much better version on YouTube.

Before Avatar appeared in cinemas, there was this rumour going around that it would be solidly grounded in biology. For a film with floating mountains in it, coherent biology may not be the first thing you would expect. Still, let's look a bit closer at that claim, and start with the natives. As narrated in the 'featurette', the Na'vi (the natives) look very human and have four limbs while all large animals have six. The reason for this apparently has nothing to do with biology and everything with economics. The director, James Cameron, made that quite clear in an interview with Playboy magazine:

Playboy: How much did you get into calibrating your movie heroine’s hotness?
Cameron: Right from the beginning I said, “She’s got to have tits,” even though that makes no sense because her race, the Na’vi, aren’t placental mammals.

So biology did not have to make sense, and in Hollywood facts and fiction do not seem to be regarded as fundamentally different, as they are in science. Oh well, perhaps we should just embrace the natives (the hero does) because there would otherwise not have been any film at all. So let's hope the rest of the Pandoran biosphere is more plausible. The first job at hand has to be how to squeeze four-limbed humanoids into a evolutionary tree in which every big terrestrial animal has six limbs; hm.

Prolemuris from 'featurette'; click to enlarge

The book 'Avatar, an activist survival guide' presents some notes on the Na'vi's presumed evolutionary background. There is an animal, the Prolemuris, that 'has two arms that bifurcate into four forearms; the upper bones of the arms have fused... Biologists believe that this may be an evolutionary precursor to the two-armed Na'vi'. There are two difficulties with this: I suspect that this arrangement would not function at all well, but, more importantly, 'limb fusion' as an evolutionary process seems utterly incredible. If you want to lose limbs, have them gradually decrease in size (the insectoid aliens in 'District 9' did have such minuscule middle legs, if I remember correctly). You might expect the resulting 'fused limbs' to look different from our own, but the natives' arms are so human that you might as well assume that human arms are the result of limb fusion. As a joke you could argue that the presence of two bones in our forearms suggests this to be true... But I really wonder how the film's biological advisors reacted to 'limb fusion'. I doubt they invented it, and surely they raised similar objections?

Thanator from book; click to enlarge

On towards the hexapods. I was not the first to design large alien animals with six legs and won't be the last. But I did think hard about how such animals might walk, and wrote computer programs to explore gaits in a six dimensional phase space to prove it. I know this sounds a bit pedantic, but the Furaha page shows I did. Just go to the land page, or directly here. One of Avatar's stars is the thanator, a large predator, as sleek and supple as a panther. Its middle and front pairs of legs are very close together, as can be seen on the image above, from the book mentioned above. The anatomy and the movement pattern of the first two pairs of legs are virtually identical, which is very odd. Other Pandoran hexapods have this same peculiar arrangement, as can be seen on the following images from the same book (the white triangles here and there are due to the fact that the images on the book were printed at an angle to the page, and I tried to rectify that).

Hammerhead from book; click to enlarge

Sturmbeest from book; click to enlarge

Viperwolf from book; click to enlarge

One result of having the front and middle legs so close together is that there is no good way to connect the shoulder girdle to the torso. The images above show that the animals have typical mammalian shoulder blades; the thanator image even shows typical mammal muscles. One such, the latissimus dorsi, can be seen running from the shoulder blade of the middle leg backwards to the torso. There are typically other large muscles running in all directions from the shoulder blade. How do you solve having two such sets in the same space?

Fragment from 'featurette'

Another result is that such legs almost certainly have to move in unison or they will collide. You typically do not get a long view of anything in Avatar, so here is a small video in which a fragment of direhorses is repeated a few times. The front and middle legs on one side indeed move in tandem. Not always, but generally they do. Mind you, there are two other solutions to avoid clashing legs that I will not go into here, but neither seems to be in use on Pandora. Anatomically these animals have six legs, but functionally they are tetrapods. I do not think that leg clashes can be prevented completely with this anatomy. With that in mind, the scene of the thanator chasing the hero could have ended quite differently: just when the thanator is about to grab the hero, the poor beasts trips over its own legs and crashes to the floor...

Again, you wonder why this design was chosen. According to one internet site one of the advisors, Wayne Barlowe, had this to say: "There was some concern as to the biomechanics of the six legs but my guess was that if they were grouped four towards the front and two in the rear locomotion issues would be solved. Those worries were pretty much put to rest after some informative motion tests were run."

But why should there be any concern about the biomechanics of six legs to start with? Six legs are part of the standard insect design, so six-legged locomotion isn't exactly a novel concept. I am not aware of any insects moving like Avatar's hexapod animals. The insect standard gait is a double tripod, a perfectly sensible solution for slow movement. Insects of course make good use of the fact that they have six legs, and, unlike Pandoran hexapods, do not pretend to have four only. The given explanation has an odd ring to it coming from someone with biological acumen, almost as if there was another, nonbiological reason for this clumsy and implausible arrangement. Perhaps the producers felt that the animals would look too alien if the animals moved in too unfamiliar a manner. I have no idea.

Go see Avatar; I loved most of it. But not for the biomechanics. Surely it would not have been that difficult to make better use of easily accessible knowledge; facts are not expensive. Not many people may notice or care, but the ones that do notice are probably the ones who care a lot.

The Future is Wild... and it is Manga!

My plans to write posts less frequently are thwarted (I've always wanted to use that word) by being spoilt for choice. Greenworld should be good for two posts, Avatar is nice, particularly the odd choices the designers made when it came to locomotion, some bandes dessinées deserve attention, etc. I decided to continue with the Japanese theme a bit. I guess that readers who really like speculative biology will have come into contact with 'The Future is Wild' (TFIW); after all, there was a television series, there are books, there is theme park in France and there are websites. In fact, a commenter on the blog once expressed irritation with an overdose of 'The Future is Wild'. I sympathise with that, as I have felt the same from time to time. After a certain point you know the images and the animals, and repeated exposure to the same images or clips no longer excites the viewer. Apparently a new TV series is in the making as well as a cinema version, so there should be lots of new images. This post is about the 'old' TFIW animals. In Japan they have turned it into a manga, or comic book, published by Futabasha. In several European countries, France foremost, comic books are regarded as an art form: the neuvième art (ninth art). Like films, their styles differ appreciably between countries, which adds to their enjoyment: 'bandes dessinées', 'comics' and manga are not the same at all. My knowledge of mangas is rather poor; it seems that almost anything can be turned into a manga, and TFIW was no exception.

Click to enlarge; copyright Takaaki Ogawa

This is its front cover. As you can see it mentions Dougal Dixon, John Adams and Takaaki Ogawa, who I gather is the artist, i.e., the mangaka. I picked up a copy through Ebay, but if you want to you can easily order it through Amazon in Japan, which has English pages. You may well wonder how you turn a documentary about animals into a manga. Easy: just add a story. That is what this book does. In fact, quite a few wildlife documentaries do exactly the same. There are about 250 pages, containing 8 stories as well as a glossary, and introduction and some other bits and ends. There is some anthropomorphism, in which animals' emotions are shown on their faces in a way recognisable to humans (by the way, the image language the Japanese use seems to differ a bit from European usage, but not so much that the message is lost -I think!-). But adding anthropomorphism is again not too dissimilar from what happens in some nature documentaries (the best do not). The various TFIW stories have different themes. I have picked out images from two stories. One story deals with an individual adult toraton (I will assume you know your TFIW, and if not, the internet will provide). A young toraton disturbs a swampus, which bites it on the neck, and the startled youngster swings its head out of the way and accidentally pokes out one of the adult's eyes. That is the setting for the following page.

Click to enlarge; copyright Takaaki Ogawa

Mind you, manga are typically printed on somewhat grayish paper and aren't that big, meaning that the contrast of these scans is much better than what you see on the printed page. The images are quite large, so you can have a good look (but downloading might take time!). You can work out the story for yourselves: the young animal dies, and the adult has lost an eye (it later dies as well). Did I mention that you should learn to read right frames before left frames, in the reverse order you are used to? I might be wrong about the story line, not being able to read the text in Japanese. If I am, I hope that any Japanese readers will correct me. The reason to choose this picture was not primarily the sad story of one toraton's death; instead, there is an interesting scene in the foreground of the last frame. Here is a detail:

Click to enlarge; copyright Takaaki Ogawa

Stomatopods, my favourite! Mantis shrimps, and on land too! Were they in the TFIW documentary? I think not, otherwise I would probably have remembered. After all, they were the inspiration for Furahan hexapod predators, exhibiting centaurism. These mantis shrimps seem to be devouring a frog together, and as far as I know current mantis shrimps are firecely territorial. So these are social terrestrial mantis shrimps; impressive. I wonder what would hapen if squid and mantis shrimp somehow would make it onto dry land. Personally, I doubt terrestrial squid would have stood much of a chance: the squid have to develop a feasible mode of walking, and the mantis shrimp have that already. I wonder whether the mangaka added the stomatopods for his own amusement? The remaining images are of the squibbon / megasquid story. I discussed the megasquid before, and decided that I did not think walking on tentacles was at all likely, and certainly not for something as large as a megasquid. For squibbons the story might be a bit different, but still they seem unlikely. But never mind that now.

Click to enlarge; copyright Takaaki Ogawa

This page I like for its graphical qualities. I can only guess that the story alludes to the squibbons possible intelligence; are they pondering the age of Earth or the size of the Universe?

Click to enlarge; copyright Takaaki Ogawa

Thirteen pages later there is this lone squibbon. being social animals, a lone squibbon is probably a sad squibbon.

Click to enlarge; copyright Takaaki Ogawa

The next page seems to show a happy ending: other squibbons offer bioluminescent thingies (fungi?). Looking at TFIW in this way may take some getting used to, but I rather like it. Computer generated images still tend to look a bit stiff or awkward, and as long as they do so, I prefer drawings or paintings. Paintings are often much livelier and they also appeal to the imagination more than CGI renderings. This manga is lively, and, provided you increase the contrast, the graphic qualities of some pages and panels is good. I found that it does not matter that much that I cannot understand Japanese. I am obviously missing some information, but I certainly cannot complain about a lack of a sense of wonder: there is quite a bit of that.

Anatomy of an Alien V / Greenworld I

This is the fifth and final post on the 1997 BBC documentary 'Anatomy of an Alien / Natural History of an Alien. Just like the previous instalment, this one deals with the work of Dougal Dixon. Although I did not plan it this way, keeping this one for last turns out nicely, as yesterday (January 29) Dixon's brand new book on Greenworld was published in Japan. More on that subject later, which explains why this post is also called 'Greenworld I'. Meanwhile, don't go rushing to your local book store to buy the English, French or whatever versions, as there aren't any. You Japanese readers, please do rush out now and buy ten copies each, so the publisher may give the rest of us an English version.

The video fragment is shown below. It does a good job of showing the evolutionary origins of the two major animal groups on Greenworld. Their common ancestor was a starfish-like animal with radial symmetry, but, unlike Earth's starfish, it had six legs, not five. When these animals came out on land they had not yet developed beyond radial symmetry, and still had no hard skeleton. Their solution was to use massive clumsy muscles first, but they developed a more practical skeleton later. In effect, their legs more or less started out as tentacles but developed into proper legs, much as I explained in my series on 'Why there is no walking with tentacles'. These animals secondarily developed bilateral symmetry. In one group the plane of symmetry came to lie in the groove (sulcus) between the legs, so the animals ended up with three pairs of legs; these are sulcosyms. In the other lineage the symmetry plane neatly divides an arm ('brachium') on one end of the animal and another at its other end. These are the 'brachiosyms', which therefore have two unpaired legs, one at the front and one at the end, as well as two pairs of legs in between. Those who have already watched the video at the end of this post may have noticed that not everything I have written here is mentioned in the video, so how do I know this? Well, Dougal Dixon sent me some notes and sketches on Greenworld a long time ago, and that's how. Mind you, the names might have changed since then, because this was 20 years ago...

If you search the internet you will find bits and pieces of Greenworld here and there, probably because the book has had to wait such a long time before it was published. Puyamaster from Japan, whose comments you can find following the two posts before the present one, searched more diligently than most and came up with some interesting material. Here are some of the things he found (with thanks!).

Source unknown

So there are (or were) models of some Greenworld animals. One is an 'anteater-sized insectivore (or equivalent)'. It is also visible in the video. My notes say it is the biggest of the brachiosyms.

Source unknown

Aha! Jack Cohen, also featuring in 'Natural History of an Alien' (and featuring in previous segments, such as the one on 'Europan waters', is shown holding some Greenworld models. When it comes to biologically sound aliens Jack Cohen is undoubtedly one of the usual suspects to round up, so his appearance here is not surprising. Still , I wonder what the occasion was. Puyamaster provided the web addresses of these photographs; their original sites are here and here. I would be curious to have a look at the site they are meant to illustrate; usually this is a simple matter of successively cutting off the end of the address until you find a readable htm file, but that does not help here. If anyone does know where these picture are from, I, and presumably others too, would be interested.

In a next post I will write a bit more about Greenworld. Here I would like to finish with some thoughts on the alien nature of radial symmetry. I guess that many of those designing alien animals consciously search for features to strengthen the 'alienness' fof their creatures, and radial symmetry has that in abundance. In discussions on the subject some seem to accept it as an acceptable body plan for big and possibly intelligent animals, whereas others dismiss it. Quite often the lack of any such animals on Earth is used as an argument. Indeed, we do not have hog-sized starfish digging up the flower beds in our gardens, and personally I deplore the absence of elephantine centipedes. But before dismissing them it may pay to try to specify the reasons why there are no such animals. A first and simple reason why there are no big starfish walking around on Earth is evolutionary competition; their seat is already taken!

Another, and possible more important reason may be sought in a respiratory system. Some arthropods have tubes entering the body supplying each cell of the body with air for gas exchange. Beyond a certain size passive gas exchange in this way is simply unsuitable, so that limits growth. Our own respiratory system does of course allow large body size, possibly exactly because it does not attempt to reach every cell; instead, that task is relegated to the circulation. Altering an unsuitable respiratory system may need going back to the drawing board to start all over again, but evolution does not do that. It either adapts another organ, or tinkers with what there is instead.

Having an exoskeleton is another difficulty: for the same strength you need more material than for an endoskeleton, and growth is a major design problem. But this particular problem does lend itself to gradual change: if you simply strengthen one side of an exoskeletal tube and weaken the other side, you keep the weight-bearing function intact while sparing weight. Repeat this a few times, and you have a weight-bearing strut that does not envelop the limb. This is evolutionary tinkering, and this is how Furahan hexapods developed a practical skeleton. This also explains why dermal armour crops up so easily in hexapods; their skin, a secondary development, can easily revert to armour production. Luckily for them, protohexapods already had a nice pumping system in place pumping blood as well as air, so they did not have to solve too many problems at one. If Earth's arthropods had has another respiratory system, who knows what might have happened?

In the end, of course, all this remains speculation. And as we all read the same books and are subjected to the same sources, we come up with the same alien designs. I've called it 'speculatory convergence' or 'convergent speculation', a concept related rather closely to convergent evolution. Dougal developed secondary bilateral symmetry for brachiosyms as well as sulcosyms. I developed secondary bilateralism as well, but only for some predatory neospidrids. You will find an example here. Spidrids, of course, are radially symmetrical, but these neospidrids have a symmetry plane going through one leg, just like the brachiosyms. Convergent speculation...

Speculative biology in Japan; help needed

Last March I asked whether anyone knew of any more sites showcasing speculative biology (here and here), and received a number of replies. Among them were Pavel Volkov who provided a list, and Josh who later alerted me to the Morae River project. What surprised me a bit was that the somewhat narrow geographical range of these projects. Most are American or British, with just a few others thrown in. Pavel is Russian, I am Dutch, but where are the others? Linguistic barriers might be to blame, but I have searched in some languages besides English, and hadn't found much. It may have to do with science fiction being less accepted in some cultures than others, or perhaps there are other explanations. The ability not to take yourself overly serious might be a prerequisite to spend vast amounts of time on an intellectual fantasy. I'm open to suggestions.

At any rate, I was puzzled by the absence of one country in particular: Japan. I know we did find one or two links to Japanese sites the last time, but there does not seem to be anything on a large scale. Dougal Dixon's book and projects like 'The Future is Wild' seem to go down well there; the thriving manga and anime culture also suggests that nothing stands in the way of a nice speculative biology project.

By the way, out of curiosity I just ordered a secondhand manga (comic) version of 'The Future is Wild'. Not that I can read Japanese, but I do not expect a comic about animals to be heavy on text. I will show bits of it here in due time, unless I find it too disappointing.

Back to the issue at hand. Luckily, there is a Japanese version of Amazon. It is partly in English, but with Google's translation services even the Japanese version makes some sense. I started by typing in 'Dougal Dixon', and then clicked the part of the page where it normally says something like 'here are similar books you might like'. If you do so, you will encounter books on 'The Future is Wild' as well as the Rhinogradentia. I found three books that looked intriguing. Their titles seem to have 'kimono' in them, but the illustrations on their covers suggest something altogether different.

Click to enlarge

Here they are. Have a look at the animal on the cover with the yellow design. We see a fish with a rather human-looking face, and will let that one pass. But behind it is what must be a flying snail. There isn't much I can tell about the others (one's a virus). Apparently these two books were published several years ago.

Click to enlarge

This one, I gather, bundles the other two. It's the fish again. So what are the books about? Somehow the fact that here is a text I cannot begin to understand adds an alien touch that rather fits the subject. Anyway, there were customer reviews, and here is what Google's translator program made of one of them:

"I have to muster Kimono - Graffiti The Unusual Biology (book (soft cover))

This book is "Kimono not Enough" "Enough and footwear also not" is omitted the bound volumes and some from column. (→ did not have these books the reader (me) this is advantageous to) a real strange creatures and 130 species Journal. Facing two strange creatures are a kind of introduction page. (Real-page black and white illustrations on the right (+ Omake occasionally) witty comments and a short description page on the left) you can pick up to read from anywhere. Look at the illustrations feel Idaki Kosobagayui (→ ...), but dreams do come to read the comments or grin, or wonder. It's not boring the reader is this. While reading "What appeared Kettai biological ecosystems do it?』 Or 『evolutionary theory to explain it I wonder?" It makes the question of nature and inspire. This year (2009) The 200 birth anniversary of Darwin's Origin of Species marks the 150 anniversary of publication, this book is suitable for one year I Memorial is such a book (laughs). This book is a serious book of biology, despite not promote reading as "a serious and』 or 『Let's theory of evolution-related reading a book" that "curiosity" and consequently Yo clock has a clock."

Right. Too bad Star Treks's universal translator is not quite ready yet. Still, most can be understood, and this indeed seems to be a work on speculative biology. The reviewer thinks it is serious biology, meaning he is probably like me or you. Some other sentences baffle me; 'Yo clock has a clock' sounds good though.

I know that this blog is occasionally read by people in Japan, so I am asking those readers for help! Are these books really about speculative biology? Are they good? Let us know!

Anatomy of an alien IV: Sulfuria

Writing this a new post took a bit more time than usual, for which there are two reasons. The first is that quite often I simply run out of time. In fact, I have found that putting up a post almost every week (I did 50 in 2009) is about enough to stop me working on new content for the Furaha site. For that reason alone I may decide to slow down a bit.

The second reason is that I had lots of problems in trying to upload videos. The main reason was that I tried to do it with software I was unfamiliar with (Adobe Premiere Elements). I could make great titles with it, but the resulting file was about 850 Mb, whereas comparable earlier ones were less than 20 Mb. In the end I went back to the previous painful process involving three different programs and convoluted steps. There are too many video formats, and if you are not an expert life is hard.

Anyway, in the end I managed to upload a file. Today's post is once more about the BBC documentary 'Natural history of an alien', also known as 'Anatomy of an alien'. I rather prefer the first title. After that there will be only one fragment left to post on this blog, but this does not mean that the entire program will then have been posted here. Some parts deal with life on early Earth or on general biology, and I thought these would not be of major importance to the readership of this blog.

Both remaining sections feature the work of Dougal Dixon, someone who probably needs no introduction in the world of speculative biology. For those who do not know his work, he wrote several landmark books in the field, of which I like "After Man, a zoology of the future", and "The New Dinosaurs the best". In those years he and I communicated a few times by regular mail (yes, it was that long ago).

Click to enlarge; copyright BBC 1997

The present post is about the world 'Sulfuria', equiped with a very dense atmosphere. As discussed before, heavy atmospheres lend themselves well to flight, both of the 'heavier'and of the 'lighter-than-air' varieties. One of Sulfuria's major lifeforms is a 'ballont'; for previous discussions, see here, here and here. It is not a free floating one though, but a stalked one. The story is that these beings stick out above the clouds, where they are in the sun. Presumably sunlight is beneficial to them in the sense that it drives their biochemistry, but like many details in this programme the rationale for this is not spelled out.

The ballonts are rather nice, I think, but then again I have always been partials to ballonts. One small problem is that it is very difficult to get a sense of scale, if there is nothing in the image to compare the ballonts with. It would have been nice to learn a bit more about this biotope: there may be more flying forms, and some might be involved in the life cycle or ecology of he giant ballonts. I guess we will have to make these up ourselves.

The last fragment in this series will be posted in the near future, and will also deal with Dixon's work. In it, he discusses another invented world, called "Greenworld". I think I still have photocopies of sketches of Greenworld creatures he sent me years ago. Unfortunately, the work did not then see the light as a book, but I read recently that Greenworld is in fact about to be published, in Japanese. I will keep my eyes open for that one; not that I read Japanese, but I hope there will be pictures...

Anatomy of an alien III: Europan waters

The first blog entry in this new decade travels back in time again, to the 1997 BBC television series 'Anatomy of an alien'. This time the chosen fragment chosen deals with life on the moon Europa, or perhaps it may be better to call it 'in Europa', as the life forms in question are found in water underneath an ice cap over 15 km thick (according to the documentary).

You will first see an explanation of deep ocean vents on Earth, and those are never boring. Jack Cohen makes an appearance again, to speculate about similar vents in Europan seas or lakes. The vents are surrounded with walls built by bacteria that stretch upwards to form very long tubes. The speculation really gets underway when it deals with the ecosystem surrounding these tubes. There are creatures that can bite or drill through the wall of the tube, after which they gorge themselves on bacteria from within the tube. Of course there are predators out there too, preying on the 'grazers'.

Click to enlarge; copyright BBC

Here is a picture of a bacterivore; the predators have almost exactly the same shape. There is a feeding trunk on the front end of the animal, underneath the central opening. There is another opening in the front end of the animal; what is it for? Unfortunately, the documentary keeps completely silent about the body plan of these animals, which is a pity.

There is an opening right at the front, and one at the back. The one in the front is not for feeding. Perhaps these are the inlet and outlet openings of its respiratory system. After all, there is no reason to have air go in and out through the same opening, as is the case in Earth's tetrapods. Actually, using the same opening for air moving in and out is not good engineering, and is probably just a remnant of lungs starting as a sac with just one opening. In Earth's fish, waters enter the mouth and leave through its sides after having passed through the gills; a much better design! Obviously, evolution should be able to find other solutions on other worlds: air enters the lungs of Furahan hexapods through openings at the front of the trunk, and exits the body at its rear end (not that you can see that on any of the paintings on the site, but is true nevertheless).

Click to enlarge; copyright Gert van Dijk

Then again, the Europan bacteriovore's openings might have to do with propulsion, in which case these animals would have the same propulsion system as is found on Furaha. Just visit the page, choose the 'water' icon; choose 'swimming with...', and then got to the 'tubes' page. There you are. To save you the trouble I copied the image to this blog message; mind you, the image shows the external appearance of the animal; to understand how it works you still have to visit the page. I doubt that this propulsion system was separately invented for the Europan creatures. If so much thought would have gone into their design, you would think that this neat feature would be mentioned, and it isn't.

Still, there is something else about their propulsion that makes me wonder. The animals have a set of three fins around their body, more or less like the pectoral and back fins of sharks and dolphins. This makes sense, as three such fins are useful in countering rotations around the body's front-to-aft axis. You would want such fins near the centre of the body, as they would impede movements around the other axes if placed at the front or the rear of the animal. These animals indeed have three such wings right where you would expect them, around the centre of mass. As an aside, you may well wonder why there are three. To counter rotations, two or four (or more) would work just as well. Their area may have to increase if you have fewer fins, and vice versa, but that does not seem to be an important factor. Some whales have large dorsal fins and some have no dorsal fins at all, so having two seems to work as well as having three. Why are there never four? Is this just an evolutionary accident? Perhaps it is easier to have more such fins at the bottom half of the animal than at the top half, if only to make it easier to keep the body upright.

Anyway, now have a look at the tail of Europan bacterivores: there is another, smaller, set of three fins. That only makes sense if the animal needs more to be kept on track like an arrow, but this 'triad' fin design is not optimal if you use the tail for propulsion. Suppose you wish to beat the tail in an up and down direction: with a triad set the top fin will be useless for propulsion. While moving upwards it might even start to bend sideways and then it would impair propulsion. The other two will not be perpendicular to the direction of movement and will therefore not provide optimal thrust. No, if you want a beating tail, the surfaces providing propulsion must be perpendicular to the direction of the beat, and surfaces not aiding in propulsion should not be in the way.

Whale shark  / orca / orca; click to enlarge

The tails of sharks and whales provide excellent examples of this design. The pictures above were taken from the internet. The whale shark beats its tail sideways, and the 'stem' of the tail, just before the tail fin, is flattened sideways. In this way, there is room for the attachment of muscles and ligaments without impairing propulsion. The two photographs of orca's show that an orca's tail stem is flattened vertically, exactly as expected for an animal that beats its tail up and down.      
                  
Back to Europan bacterivores. Their tails suggest a mode of propulsion similar or identical to the ones I invented for Furaha. Convergent speculation once again? Possibly; remember that this type of propulsion results in linear motion without any externally visible means of propulsion. That is not what you see in the video. Instead, the predators near the end can be seen to swim with a strongly undulatory pattern, like the one you would expect for animals with sideways-beating tails.

I wonder what happened to cause this odd combination of a design plan with a movement pattern that doesn't seem to fit the plan. The people who designed these animals knew what they were doing, so the answer probably does not lie there. Perhaps the animators simply added a familiar type of movement to add some spice to the footage? That is possible: I remember from conversations with Steven Hanly that the movement of Eponan uthers in the same documentary did not come out as planned either. I doubt we will ever know.

 

Mr. Fungi's Creature Journal

What I like to find during an internet search is a whole world of speculative biology, filled with interesting beings with nicely thought out backgrounds, sound biomechanical and ecological concepts, and oh yes, excellent artwork. In other words, a few years' work...

But there are quite a few creative people who design life forms for fun without all the rest of it. While a scientific background adds intellectual spice, not having one does not detract from the more primary, emotional type of fun of looking at a well-drawn animal. One example of this type of fun is the 'Diary of Inhuman Species' by Stan, who draws one species a day, as I wrote here earlier. Stan is still going strong, so do not forget to visit his site from time to time.

I came across another site with a constant stream of new odd animals, and like Stan's these animals should not be taken overly seriously. This is the 'Creature Journal' with the explanatory subtitle 'It's a journal with creatures in it'. It is written by 'Fungi' or 'misterfungi', also known as Mark A. Facey.

Click to enlarge ; copyright Mark A. Facey

Here is one of his creatures to start with: the 'mensblodder'. You can see it shouldn't be taken too seriously, can you? I asked Mark about any systematic biological background; there doesn't seem to be an intricately worked-out one, but he was curious to hear what I made of it. I'm ready to make a remark here and there, but do not want to spoil the fun by being too intellectual about it. At first I thought this might be an animal with radial symmetry, based on the legs. Then again, the upper torso and head are clearly bilaterally symmetric, so that probably holds for the entire animal. It seems to have an internal skeleton, so it certainly is no Earth insect. Not that anyone would have thought that anyway. Seeing it's legs bent this way and that, it is either not very large or must live on a low-gravity world. Mark, is that anywhere close to what you had in mind?

Click to enlarge ; copyright Mark A. Facey

It's a bird! It's a 'Cluckadon Tuft Puncher'. If you have seen films of birds of paradise, with their bizarre mating rituals and plumage, you can not think that this animal is wholly unearthly. Its posture reminded me of such birds, but I might be wrong: perhaps this is its normal standing posture. Then again, its name suggests a more pugilistic attitude: a threat posture? I would guess it is flightless, judging from the shape of its wings and its tail.
Click to enlarge ; copyright Mark A. Facey

The 'emerald nitpicker' is a tetrapod animal with an exoskeleton (look at the first joints of the hind legs); and why not? There is no rule stating that any animal with more than four legs in its body plan must be an arthropod and therefore have an exoskeleton. If  larger animals can get away with walking on four legs, why shouldn't small ones be able to do the same? I can't help but wonder why its legs are in the position they're in. Are the front legs designed to catch prey? Is it a jumping predator? Regardless, it is very eye-catching.

Click to enlarge ; copyright Mark A. Facey

The 'knuckleheaded guppy goblin', or, as I would label it, a fish. This certainly is a predator. I like the way its salmon-like head bump adds a sense of power to the animal. It's also nicely fleshy. It's not found in local waters, I think, as there anatomical clues why this is no mere Earth fish.

I hope you like Mark's animals as much as I do: they are fun and make me want to sit down and start painting immediately. In my case that usually involves oil paints, as I still have to make the -for me- difficult transfer to digital art. If any readers are in a similar stage, or wish to take up painting with Photoshop, Mark has posted a few videos showing how he paints a 'hulking shipwreck creeper'.  

This is probably this year's last post. Then again, I might decide to post some more attempts at videos showing Furahan landscapes. Have a nice 2010!