"Anatomy of an alien": high gravity

A while ago, I showed a fragment of a 1997 BBC documentary called 'Anatomy of an Alien'. The fragment in question was about Epona, which was also what the post was about. The program contained discussions of more such extraterrestrial ideas, and contained short discussions with a variety of people involved in speculative biology, a term which I do not think had yet been introduced at the time.

Looking at the program makes you realise how fast computer graphics have evolved. Admittedly, the designers at the BBC probably did not have an enormous budget available, so they may not have been able to achieve the very best results technology could offer in 1997. In that period, 'Jurassic Park' was probably the yardstick you could get if you threw lots of money at the problem, and 'Jurassic park' dates from 1993. Still, the computer effects were certainly better than what an amateur could achieve.

I do not think that this means the program is no longer interesting to watch, so I decided to show some more fragments of the program. The one for today concerns life on high gravity planets. You will see an interview with Jack Cohen, a biologist with a strong interest in biology in science fiction. He has written a few books that all people who wish to design worlds should find interesting.  One I particularly recommend is 'Figments of reality'; a search on Amazon should result in several others.

In the video, Jack Cohen goes into the mechanics of legs for heavy worlds. He compares land-living crabs with sea-dwelling crabs to make the point that higher loads require stronger and more columnar legs, an effect encountered in this blog more than once. The resulting animation is quite nice. Another point that should be kept in mind is that high gravity is largely irrelevant under water. If your body mass is close to that of water, it will not take much effort to keep floating at the same height, and a relatively small swim bladder should allow you to change height at will. There's no risk of broken limbs from tripping under water.

On land, of course, things are quite different. In a truly high gravity the simplest trip could shatter your legs, so falling is something to be avoided at all cost. Even staying upright and walking requires legs that look different from those of animals of similar size on a low gravity planet (that's why I thought that Alex Ries' Birrin must live on a low-gravity world).

Click to enlarge (copyright BBC)

The video fragment shows a vaguely arthropod-looking animal, shown above, with a large number of vertically placed columnar legs. This makes excellent sense. The animal has large wings though, and that may seem surprising. Wouldn't high gravity make it more difficult to become airborne? It would, as a moment's thought reveals: staying aloft requires that weight, dragging an animal down, is exactly countered by the amount of lift pushing the animal upwards. If you double gravity and keep everything else the same, the situation is no longer in equilibrium, as weight is now twice as large as lift. Down you go.

But Jack Cohen makes the point in the video that high gravity may also make it easier to fly, by increasing the density of the air. It is indeed more easy to achieve lift in a soupy atmosphere than in a rarefied one, and vice versa. Disney's people knew that in 1957, as evidenced by the enormous wings of his Martian flying animals, designed to fly in the rare Martian atmosphere.

I checked some books and found that the amount of lift provided by wings is directly proportional to the density of the air. Here is the formula:

lift = 0.5 x density x wing area x velocity squared x lift coefficient

What that boils down to is that doubling the density of the air will double the amount of lift. That is nice: in the example above gravity was supposed to be twice as much as on Earth, so a doubling of lift is just what we need to keep the same animal in the air. Not that is at all likely that an animal living on a planet with twice the gravity and twice the air density could be the same as one living on a lighter world, but never mind that now.

So, to make things work, the only remaining question is whether doubling the gravity a terrestrial planet is compatible with doubling its air density. I have no idea. Comparing Venus and Earth suggests that similarly sized terrestrial planets can vary widely as far as their atmospheric density is concerned, so I guess a double air density is feasible. If anyone knows more about the relationships between gravity and likely atmospheric density of Earth-like planets, feel free to comment on this post.

Springcroc in springtime (Epona IV)

The springcroc is not a Furahan but an Eponan animal. Parts of the vast Epona material have reappeared on the web, and the many life forms discussed there include the springcroc. You will find it right here. Regular followers of this blog will now that I have discussed it before (first here, and then here and afterwards here), and I will probably come back to it in the future (I was one of the people who used to work on it, so that's why).

The thing to remember about Eponan terrestrial life forms is that they left the sea fairly recently, so adaptations to a land-based existence have not yet reached optimal solutions yet. That holds for Eponan trees, whose stems have not yet evolved anything as suitable as wood, and it may also hold for the springcroc. Its general design is very nice: in essence a springcroc is just a large stomach enclosed by two half shells. It lies in waiting in some swamp, and when a suitable prey arrives in striking distance the springcroc catapults itself towards the prey using its own froglike leg. The prey is engulfed by the stomach and is slowly digested. Simple, but simple solutions work.

Click to enlarge; copyright Worldbuilders

This is the springcroc as shown on the Epona site. Steven Hanly, one of the people involved in the Epona project, produced many 3D Epona images at the time, many of which can be seen on his web page. For this purpose he had also built a 3D springcroc computer model. A few months ago he sent me his 'obj' file to have a look at. I was also trying out ZBrush, a 3D 'sculpting' program that is extremely well-suited to produce organic looking animal shapes. I imported the springcroc shape, and used it to try out some embellishments, as ZBrush allows you to push and pull at objects at will. As you will see this ability is the reason why the poor animal now has so many bumps on its head.

I also decided to 'bodybuild' its musculature somewhat. With just one leg it must be difficult for the springcroc to control the direction of its jump in a lateral direction. While a jump in the general direction of the prey can work for extremely slow prey animals, a jump with some more precision should help the springcroc to rise to the pinnacle of the food chain (or at least to stay in plaavce with more ease). The only way the springcroc can exert lateral control is by pushing harder or less hard on either of its two toes while jumping, so these are fairly wide apart. For similar reasons the joints between the segments of its leg were broadened: to provide more joint stability as well as a bit more control.

Click to enlarge

So here it is: a springcroc before and after embellishment in ZBrush. As said, the bumps serve mainly to make it look more interesting.

Click to enlarge

Having done that, I exported the model again, and after some trouble loaded it into Vue Infinite, where I embedded it in a meadow-like environment of Eponan plant (well, actually one plant was designed for Furaha, but these images are sketches, nothing more). The springcroc should really be coloured a bit more interestingly, but this is just a work in progress. The white leaves reminded me of springtime, so there you have it: a springcroc in springtime...

Disney's exobiology

Yes, Disney's.

In the 1950s the Disney studios produced a weekly television series called Disneyland. One episode was called 'Mars and Beyond', which aired in 1957. It contains experts with heavy accents explaining things such as geosynchronous orbits to very attentive serious looking young men, but it also contains a short gem showing possible Martian life forms.

If you look at that part of the episode, reproduced below, you cannot help thinking that Disney's animators must have had a great time producing these scenes. Perhaps you have to overlook some of its now outdated aspects, such as the deeply sonorous voice. After all, this footage is over 50 years old. But if you look past that there is so much creativity that it is simply contagious. Some of the life forms in there look very far-fetched, such as the crystal ones that grow overnight and are shattered each morning. The daily cycle is a very nice and dramatic notion, but crystal life forms do not seem to have outlived the fifties and sixties in science fiction. I have always wondered in which ways a crystal would be said to be alive. Thought and even intelligence are not impossible; after all, neither neurons nor computer processors appear to do anything if you just look at them. It is simpler things such as movement that cause doubt, as well as procreation and selection. But never mind that; crystal life forms seem to belong a past concurrent with Star Trek's original series (which started in 1966, just 9 years after Mars and Beyond).

The plant that eats itself also seems impossible, because of problems with energy efficiency. Some readers might point out that one's own parts might be put to better use when the need arises, such as under extreme duress. Possibly, but there might be easier ways of recycling body parts than actually digesting such parts.

Click to enlarge; copyright Disney

I really like the scene shown above, in the beginning, in which the camera pans over a landscape, and we see rocks over which luminous threads glide along in parallel. I do not know what these are or what they are doing, but I like the air of otherworldliness of the scene. Later on, there are shelled creatures that can 'clamp up' to protect themselves from sand storms, and those seem quite likely. The animals that sieve the top layer of the soil for something are a nice concept. You could imagine a thin layer of bacteria or unicellular plants living in a few millimetres of otherwise barren ground, and this biome would definitely require specialised animals to get at this source of food.

Click to enlarge; copyright Disney

My favourite, I think, is a small ballont that hangs from, well, from something. When it lets go it first inflates and then seems to fly by jet propulsion, until it is -how sad!- speared by a sessile predator. Jet propulsion with stored air, now that is a nice thought! Disney's animal looks like a simple toy balloon that is let go, but there must be ways of making it more interesting. How about storing the air under high pressure, so the amount of air will last longer? That would take a fortified bladder, the walls of which must be capable of withstanding high tensile strength. Possible. The thing is how to pump the air in. Perhaps a series of muscular 'hearts' would do, each of which would increase the pressure to compress air into chambers separated by valves? Such an animal would run out of compressed air in flight, so this mechanism might work better as an additional power source than as the sole one. Food for thought...

copyright Disney 1957

The Cycle of Cyann IV

About one year ago I first wrote about the Cycle of Cyann (here, here and here). This is a French series of graphic novel about a young woman travelling through worlds and time using an ancient portal system. It is definitely a series for those with patience, as the series started in the magazine "À Suivre" in March 1993, and now there are still only four albums. Unfortunately, there still does not seem to be a version in English. In the course of the story told in the first two albums a party searching for the cure of a dangerous disease travel to the planet Ilo. After getting down they have to make their way across a continent, encountering a variety of climates and biotopes as they go along. At one point, the party travels through a wintery place. The image is taken from a Dutch version, so now you know that what they are saying is largely not an alien language. The party is travelling in an enormous vehicle, here shown in the background. The characters discuss the 'funny animals' in the foreground, called 'ziglones'. The following images shows how the ziglones huddle together, no doubt to conserve heat. Mind you, the ziglones play no part in the story. They are just there to make the background, the world of Ilo, more interesting. It works for me...

Click to enlarge; copyright Casterman

Shortly afterwards the protagonists spot the vehicle they are following and wish to catch up with make a detour around a small valley. With the commander (Cyann) in bed, the crew charged with steering their enormous vehicle decides to cut some corners and head straight through the valley, dotted with snow-covered domes. The following page shows what happens when the vehicle crashes into the domes.

Click to enlarge; copyright Casterman

Some of you may be distracted by the appearance of Cyann on the command post. The home planet of these people is hot and humid, and they dress accordingly. Something that may also play a role is that the French regard such matters in a rather more relaxed manner than people in some other countries do. Vive la différence... Anyway, those not distracted or post-distraction will notice that the domes are filled with animals, called 'albarans'. The crew protests that they could not know that the domes were hollow and do not allow travel, but Cyann says that she did know. Knowing details about the planet and its dangers is a recurring theme throughout the book, along with how some people have knowledge they were not supposed to have. But back to the domes. The crew still thinks the albarans are kind of cute, but the lesson that is is better to be careful in an ecosystem foreign to you is rammed home by what happens next:

Click to enlarge; copyright Casterman

And that is all we ever get to see of the albarans in the story. A considerable amount of work must have gone into the design of these ecosystems. Luckily, there is an accompanying book that offers a glimpse of all the work the authors (François Bourgeon and Claude Lacroix). That one (La clé des confins) hasn't been published in English either, nor in any language other than French as far as I know. The book contains more information on the universe of Cyann. There is a double page on the albaran dome system. Not wishing to ruin my copy, I left a grey band running through the page. Basically, the dome is the result of a collaboration between a plant and a fungus, creating a home for albarans, 'lagades' (a species of bird, shown on the right), insects and even fish.

Click to enlarge; copyright Casterman

As you can see, the drawing is dotted with little asides describing elements of life in the dome. Still, much is left unsaid, such as how the dome generates enough heat to prevent freezing, or how this complex system evolved. But perhaps that would be asking too much: I can understand that the authors wish to show some details, but not all. Few things get boring quicker than an over-abundance of explanations; always leave enough unsaid to keep the reader hungry for more.

Furahan swamp scenes

I have used the 3D program Vue to produce some Furahan scenes in the past. I started when it was still called Vue d'Esprit, and now it is simply called 'Vue' (here is the website). Mostly, you will find the results in the plants section on the Furaha site. Vue is an odd program, and if you visit the forums on the website you will find people loving it but also many deploring its sometimes unexpected results, as well as errors.

One of the things that I am a bit disappointed about is Vue's plant editor. There is one, but it is fairly limited: it will let you alter existing designs, but you cannot design completely new shapes with it, and if you want alien forms, you need more freedom that Vue gives you. Of course, there is XFrog: it will allow you to do that, but it is difficult to learn and for several years now all development efforts have been directed at versions to be used with major 3D packages, leaving general users like me with the 3.5 version, that is by now rather old. Still, you can design very interesting shapes with it.

Animation is another subject that Vue must be able to do, as there are breathtaking demonstration videos available, but unfortunately most general users find it extremely difficult to get good results. In experimenting with animation I was not too disappointed, but my standards for animation might not be that high. It is possible that the latest version of Vue is better, but I am at least one version behind.

So here are two scenes from a very quiet swamp. The reasons it is so quiet is twofold: I should add some sounds, but I have never create an alien nature sound track yet. I do have ideas on how to do it, but it does not have a high priority. The other thing you will notice is that the plants and the water do not move at all. Vue can actually produce plants that move in a breeze, but that works only with its own type of plants, not with imported objects.

Copyright Gert van Dijk

You can find the same swamp in the plants section by the way.

Copyright Gert van Dijk

You may well find that the scene isn't that alien, and you would be right. I am guessing that branching plant shapes would converge in design across the universe, but I could have thrown in a few mixomorphs or ballooning plants to spice up the scene. Then again, there are items you cannot see that well. The 'spirflower' is a case in point. Flowery things are probably universal, in that it makes sense for sessile life forms to entice mobile ones to help with procreation. A flower is just an advertisement. There is no need for them to look like Earth flowers though: any form might do, I guess. The spirflower has two brightly coloured blade-like leaves in a double spiral, with small bulbs on top that exude the reward for landing there (while secreting some sexual cells, of course). Here is one in a close-up, done with Vue.

Click to enlarge. Copyright Gert van Dijk

Alex Ries and the Birrin

Those on the lookout for speculative biology that catches the eye as well as the imagination could do much worse than to have a look at the work of Alex Ries. I have kept an eye on his website for several years, and had drawn the mistaken conclusion that he probably stopped working, as the site hadn't changed for quite a while. I was wrong, and should have searched in other places. It would not have taken that long to find him again on Deviant Art. (you will find more paintings on Deviant Art by typing his name in the search box). But what is more interesting than my shortcomings are his messages there that he is planning a book on his extraterrestrial creations. He is certainly not alone in wanting to do that; in fact, aspirations of producing a book are a recurrent theme among those who spend considerable time on their speculative biology creations. His remarks reveal that the book might revolve around an intelligent species, the Birrin, so perhaps that species is a good place to start looking.

Click to enlarge; © Alex Ries

This one image speaks volumes. The first is that Mr Ries really knows his business as an artist (I wish I could paint in such a assured manner). Obviously, you can also see that it is an intelligent species (or at least it has intelligence in the toolmaking sense, and I am not certain that that is enough to qualify). Something else that struck me is what the body plan of the Birrin reveals about its planet. There is no indicator of scale, but the objects and choice of perspective suggest that the Birrin is at least one meter tall. It must live on a low-gravity world. I think so because its legs are rather spindly and stick out sideways, instead of being held vertically underneath the body. On Earth such limb positions only work for animals that are rather small, up to the size of a coconut crab, but most animals with such limb designs are smaller that that.

The reason for this is that gravity affects animals of different sizes in different ways, a subject known as scaling. It is less complex than it sounds. Suppose you make an animal twice as large in the sense that its height, width and breadth are all twice the original amount. The large one will weigh 8 times as much; that is because weight relates to mass, and mass relates to volume, and volume relates to length by a power of three. Now the cross area of its legs will be four times as much as in the original animal, because area relates to length by a power of two. The strength of legs is relates to their cross section, so what we have is an imbalance: the animal's weight has increased more than the strength of its legs. The solution? Increase the cross sectional area of the legs out of proportion. That's why elephants have thick columnar legs held under the body, and spiders have thin ones that can stick sideways. Can you have a large animal with spindly legs sticking sideways? You can, on a low gravity planet. Alternatively, the material the animal is made of are incredibly strong (how about a skeleton of biological carbon nanotubes?). The Birrin doesn't look very small but has thin legs, so I assume it lives on a low gravity world. I wonder what really small animals look like: hair-thin legs?)

Anyway, I cannot resist plugging the concept of 'centaurism' once more; the Birrin looks like its manipulative front legs have evolved from walking legs, so there we are again...

Click to enlarge; © Alex Ries

Here is another fine animal, one with (largely) radial symmetry. It is good to know that tetropters and spidrids are not the only animals in the fictional universe with radial symmetry. They have their counterparts in the known universe, with anemones and starfish and the like, but sadly we know of no animals walking around with any degree of elegance. I like the anatomical details of this one. I have no idea whether or not it is supposed to live on the same world as the Birrin.

Click to enlarge; © Alex Ries

Click to enlarge; © Alex Ries

What an intriguing shape. It is probably so intriguing because it is not immediately obvious what part does what, or why it is where it is. That is what makes it convincingly alien, I think. Is it a passive floater? It has a rather large bladder, apparently larger than a mre swimbladder would require. What are the membranes for, I wonder; perhaps they are a sea anchor to make it fave waves head-on?

Click to enlarge; © Alex Ries

This one I found on Deviant Art. This animal is an excellent example of convergent evolution. I do no just mean that it is similar in some ways to seals, turtles or plesiosaurs, with its apparent 'swimming with wings' design. I was thinking about 'convergent speculation', meaning that it resembles a design that someone else has also come up with. In this case that someone is me, but you see this happening everywhere where people sit down with a sketch pad and create new animals (while writing this I hesitated a bit with the word 'create', because creationists have tainted it to such a degree that it is difficult to use without evoking wrong connotations). The animal I was thinking about follows:

Click to enlarge; © Gert van Dijk

See the resemblance? Mine was just a very rough sketch, but it conveys the general idea; they are 'AYUS' (As Yet Unnamed Species) from the 'Fishes IV' class. There are differences too, such as the apparent size differences, with mine at about a meter, and his perhaps at humpback size. But look at the similar design of the mouth parts. Before anyone thinks otherwise, I am not saying that either one of us took the idea from each other's work. That cannot have been the case anyway, as mine was done over 10 years ago and has never been published.

It's a simple case of convergent speculation! Of course there are clear influences to be seen in some people's work pf others'ideas, I think that Alex' work looks all his own. Anyway, there are a limited number of biological principles to go around, so all of us tend to arrive at the same ones, having all been subjected to similar ideas. Luckily, there are infinite ways to arrange such similar ideas (and if that sounds a bit like Mr Spock, so be it).

Be certain to have a look at the websites I mentioned, as there is more to see there. But not enough to satisfy the appetite for more... I hope Alex Ries will be successful in getting his book published, because his work makes me very curious to see more of it.

Walking machines III: the abiological ones

A while ago, I discussed walking machines, and found that most inventors opted for stability by designing six-legged machines. There was one design that really resembled an animal in the way it moved. That was Big Dog, a four legged machine designed for military purposes. The reason it looks so biological, in my opinion, is not that it has four legs, but that it obviously has a very flexible control to allow it to cope with uneven terrain, a slipping leg, and even an unkind human 'master' that kicks the poor beast, eh, robot.

In other words, neural control is probably the prime difference between animal locomotion and man-made machinery. 'Control' goes much further than just standing upright or thinking of where you are going. It also affects leg design to a very important degree. Have a look at the following graph.



This is the result of one of my Matlab programs to animate fairly simple legs. First suppose that a leg is suspended, so when it moves its hip will stay in place and the foot will described a movement in the air. The blue dots show 100 points of just such a cycle: in this case, 50 points describe how the foot moves forward (to the left) through the air, and the bottom 50 points describe the part where the foot is supposed to go over the ground. In that section, the foot has to move the exact same distance from dot to dot, and the movement should be in a perfect straight line (anyway, if you do it this way the animation is much easier). The brown lines show a variety of ways how you could position a leg with just three 'bones' in it (thigh, leg and ankles) to link up the same hip and foot positions. Obviously, there is an infinite choice here, and in biology the nervous system decides on the best one, taking into account anatomy, gravity, lengths of bones, etc.

If you haven't got a brain, such as holds for mechanical designs, but you want a walking leg nevertheless, you will have to find a way to get the leg to move through a similar movement arc as shown in the figure above. In short, the degrees of freedom a nervous system can easily deal with must be abolished altogether. The trick is therefore to start with a defined movement provided by a motor, such as a rotary movement, and to devise a system of links and levers to end up with a foot moving though a suitable path. Some people actually solved that problem. Let's have a look.




One of the first must be the Russian engineer Chebishev, brought to my attention by Pavel Volkov (thanks Pavel!). Pavel also pointed me towards the video shown above, an animation of how the system was supposed to work. Here it is in its YouTube home if you prefer that. I have no idea of how this engine was supposed to be powered.




The impressive machine ambling along on the video above is a strandbeest. Theo Jansen's 'strandbeesten' (which is Dutch for 'beach beasts') must be the most famous of this type of walking machine. His designs are marvels of engineering as artistic wonders as well. They have to be seen to be believed (before anyone asks, no, I have never seen them with my own eyes, which is something I should rectify one day).

Personally, I have found that I had to watch it, and others like it, quite a few times before I began to understand how the legs move. Apparently Mr Jansen made use of an evolutionary approach to work towards the optimal proportions of all the struts and links that make the legs behave as necessary. If you type 'Jansen linkage' into Google, you will find that many people are equally fascinated, so the 'Jansen linkage' seems, like any good meme, to be spreading and evolving. If you wish to se it in more detail, have a look at this site, where you can even play with design to see if you can improve the output. His devices have been copied in wood, cardboard, and other materials. There are Lego examples as well.




The one shown above is made from wood. It has a very clever gear system that ensures that only one leg is off the ground at any time. The YouTube text says that this is a stop-motion animation. Its website is here.

There are other approaches as well, such as the Klann linkage. It results in a more spidery walk, as can be seen by a direct comparison of the two linkage systems. This system has spawned several large mechanised walkers, to be found through Google or through the Klann site.

Do these designs lend themselves to 'biologification'? In other words, could I or someone else use them for a fictional animal? I can think of no reason why it should be impossible to have a pantograph-like leg. But why would you want a leg that can describe only one movement? All adaptability and all flexibility are thrown out of the window. If you throw in a fairly decent nervous system instead, you can solve the walking problem and do much more besides. So no, I do not think that this is a mechanical design that would work well in biology.

But that doesn't stop me admiring and enjoying the ingenuity of designs such as the strandbeesten!