Wednesday, 22 December 2021

What does it take to make a reindeer fly?

This blog is about 'Furahan Biology and Allied Matters', and today we will stretch the 'allied matters' a bit, to produce this special Christmas post. Somewhere in Speculative Biology there must be a place to think about re-engineering mythological life forms, which is what this post is about.

The starting condition is simple. Thanks to globalisation, a most unusual subspecies of reindeer (Rangifer tarandus) has spread widely from its original area, so it can now be observed in skies over many parts of the world. In the skies? Yes, because these reindeer fly.       

It is not clear whether these reindeer can fly in their natural state, as they are only observed to do so when tethered to sleighs. This is slightly worrying, but even so, the force that keeps them in the air must be magic, as the reindeer lack any observable physical means to provide lift. While magic is a potent force in the imagination, in the real world it is noticeably difficult to acquire, so we need a more pragmatic approach. 

What would it take to make a reindeer fly in the real world? And I mean 'fly', not hurtling it through the air by strapping a jetpack to its back or using a large catapult. No, it must fly though biological means. The first problem is that reindeer have no wings, so we will have to use advanced creative bioengineering and splice in some wings. Done! That was quick...

Reindeer weigh around 100 kg, if we average estimates of male and female weight. But even these brand-new wings won’t make a 100-kg reindeer fly. And don't you start objecting that some pterosaurs weighed more than 100 kg and could still fly. We could in fact probably re-engineer the flying reindeer to achieve pterosaur-like mass, but the result would definitely look a lot like a pterosaur, and it should look like a reindeer, right?
Where was I? Oh yes, the 100 kg mass is a problem. Why? Well, take a 0.6 kg pigeon with a 70 cm wingspan. If you double its length, width and height, you get a wingspan of 140 cm and it will weigh 8 times the original weight. That factor 8 represents doubling of all three of length, width and height, so it is doubling to the third power (2 to the power of 3). By the way, for more on basic scaling of animals, see these posts here and here.

The problem is that lift is proportional to wing area, and area is proportional to the square of length. Doubling the pigeon's size makes the wing area four times larger, but that four times larger wing must carry eight times the weight. That won’t fly. (Sorry for that one.) We can make the wings extra large to compensate for the larger weight, but that will also increase weight. As explained in another post, at some point of increasing body size the wings can no longer carry the body.  

The obvious solution is to shrink the reindeer until it weighs as much as something that can fly. Say a rather massive goose at about 5 kg. Some calculations reveal that the reindeer's length should then be 25-30% of the original length of 180 cm.

To allow room for massive wing muscles, everything else must be reduced in weight: to decrease gut size it needs a new diet, mostly sugar; we can then also abolish the teeth, because it doesn't need them and won't get caries. We'll give it slender legs, tiny light hooves and fluffy hair. You will probably insist on antlers, so antlers can stay, but they will be much reduced. We can splice some red bioluminescence into its nose, to put the cherry on the cake.    

Done! A realistic flying reindeer! 

Click to enlarge; copyright Gert van Dijk & Roelien Bastiaanse


Happy holidays!

Thursday, 16 December 2021

The aliens of the TV-series ‘Invasion’ (also: ‘Inversion Fish II’)

All episodes of the first season of the TV series ‘Invasion’, from Apple, are now available for viewing. If you are still planning to see the series later, stop reading now, because there are spoilers ahead.


The series shows an alien invasion of Earth from the viewpoint of a few individual people, here and there on the globe. The protagonists at first seem to be people randomly caught up in the events, but some later wind up playing more important parts. I wouldn’t be surprised if all of the remaining apparent bystanders will end up being close to the centre of things, but that will have to wait for future series (a second series has been ordered).   

In the early episodes no-one has a clue what is going on, an that includes the protagonists as well as the viewers. That uncertain state lasts quite a while, because the series is no hurry at all to speed up the story or to explain where it is going. This may be a reason why the ratings haven’t been very high. Personally, I do not mind that the story unfolds slowly. This ‘strategy of keeping the viewer in the dark also means that the makers do not explain much, and so did not have to insert the kind of technobabble that is often used in science fiction series to explain alien technology or biology. In fact, there was almost no explanation of how anything works, which was fine with me. 

There was one instance of an irritating wilful neglect of knowledge in the series: a child lies shaking in an apparent MRI machine with an EEG cap on, resulting in an apparent MRI image with overlaids spots of colour, prompting a passing neurologist to say that the EEG was flat. That's not how MRIs or EEGs work; I guess that a real EEG wasn’t considered impressive enough.  

Anyway, it takes quite a while before you see the actual aliens. When you finally do, they are just dark blobs from which spikes shoot out towards a nearby floor, wall or ceiling. You typically do not see them moving in great detail, but it is clear at one point that they more or less ‘invert’ themselves. That is not easy to explain in words, so it is good that the producers posted a short video on YouTube about how they designed the aliens. 

Here it is. The commentary at one point includes the following: ‘A biological entity that we cannot even begin to understand’. Well, I am not going to take that at face value... 

In science, it is always time begin doing just that. Of course, here we do not have have to deal with real alien biology, but just with a human design, and what one human can design, another can understand.
You may have to watch the video a few times to see exactly what happens. I still found that difficult, so I made a slow-motion version of part of the video.

And here is that version. Aha. Let’s analyse what we have seen. 

The aliens are roughly cylindrical, about 60-80 cm in length, with a diameter about half that. If they would be solid cylinders they would have a volume of 42 to 100 L, but they must be hollow, so I estimate their volume to be 30 to 60 L. If their density is the same of that of Earth animals, their mass would be 30 to 60 kg. If they would be denser, say with a density of 1.4 kg/L, their mass would be 40-80 kg. That makes them quite hefty.  

‘Inversion fish’
The animation shows rings coming in from the centre, moving forwards and outwards, after which the rings move backwards again, where they no doubt move back inwards and forwards again. The spikes on the rings can be seen to point forwards at first. Then they move backwards over the surface of the rings. I do not think that the rings are separate objects. It seems to me that they form a contiguous surface instead, one that moves over the substance of the animal. You could say that they invert themselves.

Believe it or not, but inverting animals, consisting of a torus with exactly such a gliding surface, has already been discussed on this blog, back in 2013. That discussion was inspired by Thomastapir’s ‘Moebius fish’. I called the resulting type of animal ‘Inversion Fish’, assuming such animals would be small and simple sea creatures, like jellyfish. With all the inversion going on, it would be difficult for them to form brains or guts, so such animals might have non-invertible parts. I meant to follow that first post later with a second one on the same subject, but I never did, for a variety of reasons. The good news is that I can label this post ‘Inversion Fish II’, bringing closure to that long-open end.

I now resurrected some old Matlab routines to animate the inversion fish and pimped them a bit. Here is the result of that; the Inversion Fish is still a simple ring, but it is now rotated to make it swim horizontally. The lines sticking out represent hairs that will help propel it through the sea. The animal was supposed to be at most a few mm in size. 


Here is a second animation: I stretched the animal to give it a cylindrical appearance, so it begins to resemble the aliens. 


And a third one Inversion Fish, cut in half. The cut surfaces help to visualise the movement of the surface. Note that the surface moves forwards on the inside of the animal, while it is moving backwards on the outside, with not much distance between the two. There is no way to attach the surface to the inner substance of the body, in the way our skin stays close to the underlying tissues. In essence,  something like this can only work if the surface is essentially loose from the subsurface. The easiest way to achieve that is with a fluid between the surfaces. That is why I compared the Inversion Fish to jellyfish: jellyfish are essentially also membranes with jelly in between. But in their case, the membranes do not move in opposite directions.     
The spikes
The spikes appear at various points on the bodies, shoot out quickly and in doing so vary in length. They are always straight, never curved, and their width tapers to a pointy end. These ends apparently attach themselves to walls, ceilings or the ground. I did not see anything in the way of suckers, feet, hooks, nails or anything else that could help to attach a fairly large mass to a ceiling or wall. The spikes do not leave any marks either, as far as I could see. What also struck me is that I did not see the spikes sagging in any way. If you use a rope to suspend a weight from a wall or ceiling, the rope will sag a bit. These spikes are also used as rigid legs, and so must be very rigid. All in all, they must be able to withstand compression as well as tension easily, even while they are being formed.  

Now making such a material presents quite a design challenge. Which material can be extruded and absorbed at will and can remain very rigid and strong while it also behaves as a fluid? The commentary says ‘It’s made of ferrofluids, so it can be hard, but when you touch it, it moves like mercury.’ I cannot say I know much about ferrofluids, but my short foray into the subject suggest that the term 'fluid' should be taken quite literally. I did not see examples of hard ferrofluids.

Could you evolve animals using ferrofluids biologically? Obviously, evolution has no preset aim and cannot set out to evolve a ferrofluid. Evolution could start with a readily available source of ferrofluids, or there should be a reasonable reason for an animal to produce them, and after that it can evolve in a different direction. In other words, how do you wind up with tiny magnetic particles permanently suspended in a fluid? And how would you wind up with a handy biological way to acquire and control magnetism? Those are extremely tough challenges, and I doubt they can be met.    

Are these aliens original? Yes, very much so, unless you feel that ‘original’ may only be used for something that that has never been proposed anywhere. That would not be the case here, as witnessed by Thomastapir’s Moebius Fish and the later Inversion Fish. But that is asking too much: I really like the inventiveness shown here.   

Are they realistic as products of biological evolution? I very much doubt it. It will not be easy for biological evolution to come up with an animal whose living matter is essentially the fluid surface of a torus, and in which that living matter can become strong and rigid at will. We should probably add some additional problems here: the animals have no recognisable sense organs, and their brain and other relevant organs would have to be malleable and able to continue working while being inverted (but perhaps you could actually do something like that to an octopus brain, while it would continue working; don't try it!). At the end of the series, the aliens all collapse when the mother ship is destroyed, which is in Earth orbit. The aliens must therefore have a means of constant communication that functions immediately over large distances; should we add radio to their list of improbable biological feats? 

Perhaps it makes more sense to treat them not as the product of biological evolution, but as the result of engineering? Are they in fact bio-inspired robots? I guess we'll see in future series.

Sunday, 21 November 2021

What does a Hexapod gallop sound like? (1)

Click to enlarge; copyright Gert van Dijk

 The image above represents one of the very first Furaha images ever, painted way back in the previous century. The planet did not even have a name yet, and I certainly had not thought much about biomechanics. I just tried to paint an interesting and pleasing picture. These primal hexapods were fairly insect-like, with a stiff-looking body. The details where the legs join the body suggest exoskeletal parts as much as they could represent skin flaps. I can show the painting here, as it will not feature in The Book: it doesn't fit anymore. 

But I still like the scene very much. In my minds' eye, I can see a large herd of these impressive animals ('handlebars' or 'handlebar-horns') enter the scene from the left, advancing towards the right, until they turn towards the camera, wheeling like cavalry. That scene deserves to be done again, with new and updated handlebars. The update does not only require revising their anatomy, as part of the Great Hexapod Revision, but their gait as well. After all, if you paint a fast-moving hexapod, you should have an idea how its legs should be positioned. Imagining six-legged walks is apparently not something that comes naturally to all illustrators: many, including brilliant artists, fell back on on four-legged locomotion patterns, and simply added additional pairs of identical hind legs until the required number of legs was reached (see here, here, here and here). I never liked that, even though I realise that doing otherwise asks a lot of an artist who may not be familiar with the gaits of insects and other invertebrates. 

Perhaps I am being too difficult about this; after all, the viewers are likely to accept the result anyway. When you looked at the handlebar painting, did you think 'I wonder whether that gait is correct?' My guess is you did not, but I still wanted to do better. I like to think that a fairly thorough biomechanical background is a selling point of Furahan fauna; I also do not think I could let it slip anyway... 

Click to enlarge; copyright Gert van Dijk

I therefore wrote a suite of programmes to help me design decent hexapod gaits. In fact, I wrote them again, as I had done so once before, in 'BBC Basic' on an Acorn Archimedes. There are still a few animations on the main Furaha website that survived the transition to other operating systems. The programmes did not. This time, I wanted to do better, meaning that the programme should find out how to fold a leg by itself, rather than requiring me to control each minute limb movement by hand. I thought that that would be tricky, and it was... I had to settle for limbs with three main segments, as I could not yet add a fourth one the position of which looked convincing enough. You will just have to imagine the feet. I will use the program as background material to design paintings, and I can add details myself. The programme does allow body position to adapt to the chosen gait, so that part works. 


Here is an example of such a three-segment limb. The programme uses segment length, built-in movement restrictions of the joints, and the phase of the movement cycle to control the thigh angle. The other bit of information is where the foot should end up on its motion path. Together, that is enough. The movement is a bit uneven, because the programme chooses from an array of possibilities, and I should have increased the number of possible solutions. 


This shows what happens when you vary the choice which joint should 'stick out' the most. The further a joint is from the vertical, the more energy is needed to keep it in that position. You can see here that making life easier for one joint makes it more difficult for another. The middle position looks like it provides a nice middle ground in that respect. In biology, an optimum usually represents a compromise that minimises the overall energy required. 

Click to enlarge; copyright Gert van Dijk

The basic hexapod anatomy these days consists of six fairly similar legs that all have 'zagzigzag' pattern, (see here , here and here), meaning the most proximal segment ('coxae' or thighs) generally point backwards. I chose that as I could not find a convincing argument to state whether zigzagzig or zagzigzag was better. The legs are not identical, though, and future hexapods will see more pronounced differences. In the pattern shown here, the middle pair of legs is stouter than the front and hind pairs, and their feet are placed wider apart. That latter bit of information is only visible if you look at the 'support diagram' under the beastie. Placing some feet wider apart is a trick to avoid leg collisions, although it is not strictly necessary: Earth tetrapods manage to avoid collisions just fine with similar distances between pairs of limbs. 


And here is one complete hexapod in a slow walk. The sounds were taken from sound recordings of horse hoof beats, because I had to use something; it doesn't mean the animal has hooves! Keen observers may well deduce some as yet undescribed anatomical information from the animation. 

So how about the gallop sound? Next post!

Monday, 1 November 2021

Are there dragons on Furaha?

 No, of course not!

Dragons are mythological beings, usually shown as very large scaly reptilian animals with four legs and two batlike wings. Did I mention that they breath fire and that some of them can talk? Of course, there are no such creatures on Furaha, but the human citizens of the planet did not shed their myths when they relocated to another planet, so they brought stories and depictions of dragons with them.

The citizen-scientists duly observed, with great interest, that six-legged beasties had taken to the skies and now had evolved into excellent flyers (‘not long’ should be taken literally: the animals flew around the spacers’ heads the moment they stepped out of their ship). Closer inspection revealed that some of these animals had four wings (and two legs) while others had two wings (with four legs). 

Click to enlarge; copyright Gert van Dijk

Later speculation suggested that both groups, the Quadrialata and the Dialata, had separately evolved from animals using membranes between all six legs to glide down from one tree to another. In one group, the middle pair of limbs had increased quickly in size, whereas the front and middle pair of limbs turned into wings in the other group.

While the scientists started studying mechanisms of lift and anatomical adaptations to flight, classifying everything meticulously, the general public took one glance at the four-legged two-winged avians and shouted ‘They’re DRAGONS!’. Now, scientists generally dislike lay people interfering with their subject matter, and protested that the animals were not dragons at all; they were ‘Dialata’, not dragons, and dragons did not exist anyway.

Of course, this resistance was futile, and the concept of ‘Furahan dragons’ was quickly assimilated by everyone except the scientists in question.                 


So much for the ‘in universe’ version of dragon lore. What happened is that the ‘Great Hexapod Revolution’ is in full swing, and I am now working on flying hexapods. The good news, by the way, is that I now think that I only need to do about four of five new paintings to finish The Book. I am aiming at some 140 pages, so you will get your money’s worth (if I find a publisher, that is).  

The unfeathered bird by Katrina van Grouw


I am working on my first painting of a Dialate flyer. I took the revamped general hexapod body scheme and thought about how it would need to be modified to become a successful flyer (also see here). Beautiful examples of such anatomical adaptations can be found in the book ‘The unfeathered bird’ by Katrina van Grouw. The image above was taken from that book, and shows the extent of anatomical  modifications.

The elongated hexapod body would have to go, to keep the mass centred. That meant that the frame of the animal had to be shortened, with the hind and front legs bending down towards the middle of the animal. These walking legs also became small and slender, whereas the wings, the middle limbs, increased in mass. The wing skeleton resembles the ‘bat mode’ more than the ‘bird model’, as it has  intact ‘finger’ bones. Of course the toe/finger pattern is not as nicely radial as in Earth’s vertebrates, but flows a Devonian branching pattern instead. The wings themselves are only partly membranous, so they do not really resemble bat wings that much.  


Click to enlarge; copyright Gert van Dijk

Here is a simple model done with Zbrush. People can achieve amazing results with Zbrush, but I am definitely not one of them (and I am not alone in disliking its complex convoluted completely counter-intuitive interface). The body and walking legs are sculpted and show the by now general zag-zig-zag basic hexapod pattern.  The wings are only shown as a sort of scaffolding (‘Zspheres’). Their Devonian branching is obvious. 

Click to enlarge; copyright Gert van Dijk

Here I have given up on making the sculpt follow the scaffolding, so you only see the scaffolding. The scaffolding is NOT the animal’s skeleton, but just a shape placeholder (the bumps on the body just indicate its size). Notice how the walking legs are tucked away against the body. 

Click to enlarge; copyright Gert van Dijk

And here is the same animal (Draco umbraferens), clinging on to a reed or stem, looking down to see if here is anything in the water it might eat. It unfolded one wing to provide shade, either to lure animals to the shade, to see better underwater, or both.

I liked that pose, so I developed it further. I am not going to show the painting, which isn’t finished yet anyway, but thought you might wish to see part of it. The Draco will be sitting on a reed in a marsh in bright sunshine. I used Vue Infinite as I often do to compose the scene to help with lighting and perspective, but only roughly. 

Click to enlarge; copyright Gert van Dijk

The scene provided a challenge, as it deals with reflections, transparency and shadows. The image above shows a detail of the future painting: a background plant. Panel A shows the shadow the plant casts on the marsh bottom; B shows the part of the plant that is underwater; C shows the shadow the above-water parts of the plant casts on the water surface; D shows the part of the plant that is above water, and E shows the reflections of that part on the water surface. Finally, panel F shown all parts together, with transparency adjusted to provide a realistic image; or I hope so anyway. The Draco and the reed it sits on will be constructed similarly.

That's it; the next post will probably be about hexapod gaits, and will include the sounds of some gaits, including a hexapodal gallop…      

Wednesday, 1 September 2021

Trying to sculpt a dinosaur (Sauropelta)

This blog and the Furaha project are about speculative biology, so there is no reason to talk about dinosaurs. Then again, you could argue that there are so many unknowns in palaeontology that it is to a large extent a speculative discipline. 

Anyway, I decided to sculpt a dinosaur with polymer clay. Why polymer clay? It is perfectly possible to sculpt digitally, with more detail, and cleaner too. I do so habitually to help me decide on shapes and perspective. And if I would want a physical object, I can order a 3D print. But physical sculpting has its own rewards, and sometimes I would like to have a nice statuette of a rusp or another Furahan animal. 

Why a dinosaur and not a rusp? In the distant past I had used 'Fimo' and 'Das' to sculpt animals, but I was never satisfied with the ease of use or the level of detail. Still, I kept an eye on what people did with Sculpey and similar materials. There are people on YouTube, such as 'Kayakasaurus', who make very nice dinosaurs in polymer clay. I thought that my first attempt would probably not be very good, so I chose something I did not care about that much, which may sound strange. But anyway, that is why I chose a dinosaur. Perhaps foolishly, I chose a material that looked interesting but for which there were not many didactic video's: Cosclay. That is a polymer clay that after baking was supposed to stay flexible, allowing very thin parts without risk of breaking. The video shows that this was indeed the case.


The video above shows the result of that experiment. I have also uploaded a version with better resolution to YouTube. 

I will leave it to you whether the attempt was successful or not. Among the things I learned was that I need to have much better control over details, and that means I need a working environment with better light and preferably a magnifying glass. 

The working method was copied from YouTube videos. I started with a nice skeletal drawing by Gregory Paul, from his excellent book 'The Princeton Field Guide on Dinosaurs'. In spite of the title, it is not a Field Guide; how many field guides preferentially show animal skeletons? 

Click to enlarge; copyright Gregory S. Paul

Here is a drawing of a Sauropelta skeleton from that book. I used the trick of printing a scanned image on the desired size, so I would end up with a roughly 1:16 scale model: the model is about 25 cm, half of which is tail. 


Click to enlarge; Carpenter K. Can J Earth Sci 1984; 21: 1491-1498

I also had a quick look at some published papers on Sauropelta. Above you see drawings from a formal 1984 paper. Compare the posture and the length of the spikes to the drawing by Paul. The fossils may not have changed much, but the reconstructions certainly do. What I like about the 1984 paper is the emphasis on how close the left and right feet are to one another. I tried to do that in the model, but probably still used too large a distance. 

Click to enlarge; Brown et al Current Biology 2017; 27: 2514-2521

And here is a recent drawing of the Sauropelta skin bones that form the large back shield (the 'pelta') . I only found it after I had already baked the final model, so the shield bones on my version are much too big. An accurate dinosaur model would require a large amount of study. Looking at other reconstructions makes me think that most reconstructions rest more on speculation than on science. Mine included! 

But at least I think I am ready for a rusp sculpt now. But first, more painting, and perhaps a stegosaur sculpt, just to be certain.

Monday, 16 August 2021

How global warming changes the future's past in the Furaha Universe

'The Book' starts with some explanations about the planet Furaha, how humanity got there, why anyone would choose to go there, as well as some other background material. The image above gives the reader an idea how large the planet and its two small moons are in comparison to Earth and its large moon. A variety of techniques were used to make it. First of all, for something like this a 'digital elevation map' (DEM) is needed, showing elevation on a grid of longitude by latitude. Such maps are easy to find, for Earth that is, and Matlab's mapping toolbox offers many ways to play with maps. Obviously, I had to make my own DEM for Furaha. The intermediate stage is to make a nice digital map in which colours represent elevation. Second, take a suitable 3D-program and set up a scene with spheres in it. I still use my 2014 copy of Vue Infinite to do so. Then you just wrap the maps around the spheres, set up some light, and you get a nice picture comparing two globes, one representing Furaha, one Earth. However, I increasingly felt that the image I used for Earth might not be appropriate for the future. Mind you, I have never settled on a period in which the future history of Furaha is to take place. Is it the 24th century, like Star Trek? Sometime earlier or later? I do not know and do not care too much. However, the Institute of Furaha Biology is at least some 200 years old, so at least two centuries are needed for that. Moreover, a 'Faster-Than-Light' drive, or an 'Around-Light' drive for that matter, does not seem around the corner, so perhaps we need to give that some time as well. Overall, we are probably looking at at least four centuries. Would the overall contours of the continents look different? The recent report on global warming makes me wonder how much sea level might rise. Humanity is causing global warming, and it is too late to prevent all of it, but part of it can be prevented. If people act in time and wisely, that is. Will they, or will it be a case of too little, too late? The Book is a science fiction project, so the choices are fictional. In the Furaha setting, in that far future, wrong choices were made. All of the Greenland ice melted, and all Antarctic ice, and so the sea rose. By 70 meters. I found that number on the internet as a rough estimate of what would happen if all the ice melted. Wikipedia tells me that Greenland is good for a 7.4 meter 'sea-level equivalent', and Antarctica supplies 58.3 meters, so together they account for 65.7 meters. That is still a sizeable amount.
I took the elevation data and adapted them to reflect a 70 m rise. I then had to edit some areas manually, because the program found some inland areas that it now regarded as 'sea', even though those areas had no access to the oceans. Large parts of the UK are gone, as well as the Netherlands, Denmark, Bangladesh, etc. No current coastal city would escape unharmed. I have no idea how such a change would affect the climate, pollution of the seas and myriads of other matters. In the Furaha universe civilisation endured, because otherwise I would have nothing to write about. But I think these fictional future people would look back to their past, our future, with perhaps some new hard-won wisdom. The citizens of the Furahan Institute of Biology passed a unanimous vote to change the formal scientific name of mankind. They abandoned the old familiar name 'Homo sapiens', meaning 'wise man', and changed it to 'Homo semisapiens': man who is half wise. They felt that wisdom must have two parts: the first consists of the ability to think, and the second requires that those thoughts are acted on. According to the Institute, humanity passed the first criterion, but failed the second.

Monday, 19 July 2021

The great hexapod revolution and Furahan Fishes' evolution

 In the past I had remarked that I was trying to solve two evolutionary puzzles concerning hexapods, the last major animal group needed to finish The Book. Well, those puzzles were solved, so I am now busy with the Great Hexapod Revolution.  I worked on the puzzles off and on, and realised that there should really at least be a sprinkling of plants, small insect-like creatures and mixomorphs. These expanded The Book from 100 to 130 pages. I guess that number means I can safely lower the number the hexapod paintings to keep the book manageable.        

The 'revolution' means that there will be changes to the anatomy of just about every hexapod I ever painted. I will therefore revisit some old paintings and give them a makeover. The process also deciding which characteristics should be included and which had to go. Once I had a list of useful characteristics for terrestrial hexapods, the next problems was of course how they actually evolved.

That meant I went back to the drawing board for Furahan 'Fishes'. (I know that 'fish' can be singular as well as plural, but the English language also had 'fishes', in particular when multiple species are meant,  and Furahan biologists used the term in that meaning. Blame them, not me. )

Anyway, for those who are not up to date with Furahan cladistics, there are six groups of Furahan 'Fishes', numbered I to VI, for which example species had already been painted. The anatomy of Fishes I to III needed a bit of tweaking, and I did not like the paintings much anymore.

Click to enlarge; copyright Gert van Dijk

This was the previous, now discarded, image showing Fishes I. The shape is well visible, and the major Fishes I characteristics are there for all to see: two lateral membranes, no jaws, four eyes, and some respiratory openings along the bottom. As an illustration of these traits, it works. But it looked too schematic and a bit boring: a living animal will have peculiarities common to its species or even to it being an individual, and those were completely absent.


Click to enlarge; copyright Gert van Dijk

So here is the new picture showing Fishes I: there is a background to make the image more appealing, and the animal has more individuality, I think. I leafed through my cephalopod books and was inspired by iridescence and partial transparency of some species. I wondered whether I could pull that off, and think I succeeded reasonably well. Close observers will see that there are now openings on the back of the animal too; well, that is because Fishes I now come with four respiratory canals. It's part of the revolution...

I have never shown much in the way of evolutionary trees, and the ones I did were not meant to be included in the book. However, I thought that I should perhaps include one or two cladograms in The Book, so I made a table showing characteristics of the six groups of Fishes to help with a cladogram of Fishes I to VI.  

Click to enlarge; copyright Gert van Dijk
Here it is. It has the 'diagonal form' you often see in biology books. When I first encountered cladograms, this diagonal representation really confused me. If you start at the bottom, you reach most species by making some sharp turns, but there is one route up that involved just one straight line. Perhaps it was my strong preference for visual matters, but the relation between the two species connected by that straight unbroken line seemed much stronger than any route that involved zigzagging. But that is not true at all: the fact that there is a split (a 'node') is meaningful, not at which angle the lines depart from the node. It turns out I was not the only one who tended to interpret such diagrams the wrong way: students learning biology have more trouble with diagonal than with 'bracket' diagrams. Well, stop making diagonal cladograms!


Click to enlarge: from TR Gregory, Evo Edu Outreach 2008; I: 121-137

That point is well made in the diagram above. The source is free and very readable. If anyone else also has trouble with cladograms, dendograms or phylogenetic trees, including remembering the differences between them, I recommend this paper: it lists the 10 most common misperceptions of such trees. It is very clear. But I cannot help thinking that if there are no less than 10 common misperceptions, there are probably even more uncommon misperceptions, and then I start wondering if there is no easier way to teach evolutionary relationships.


Click to enlarge; copyright Gert van Dijk

So here is a very similar tree but now every line running up to a node is vertical before it reaches that node, and the two resulting descendant lineages depart from the node in a symmetrical way. It is much more intuitive, I think!

Some of you will have noted that, according to the cladogram, Fishes IV and VI have a more recent common ancestor than either does with Fishes V. In other words, Fishes IV and VI are closer related than IV is with V or V is with with VI. Oh dear! Shall I keep that in, and blame it on a mistake of early Furahan Biologists? Or I could just exchange the labels 'V' and 'IV'? Or I could go back to names I came up when I thought I might still need not just names for the Species and Genus, But also for the Familia, Ordo, Classis and Regnum (the Latin names of the groups of the old Linnaean system): Fishes I would revert to Clavifluitati, II to Gnatha, and III to Penpinnata. I will think of something.

Anyway, onwards with the Great Hexapod Revolution!  

Friday, 11 June 2021

‘Wadudu Castles’, or Furahan 'termite mounds'

I needed a background for a painting.

Every chapter in The Book at present starts with a double page showing a painting supposedly made by someone in the Furaha Universe. These paintings are all about humans on Furaha. Some are portraits of dignitaries, whose illustrious career earned them the privilege of forever having their countenance grace the Halls of Academia. Or, of course, until someone else comes along with even more vanity and money. Such portraits do not need much in the way of background; a generous helping of 'Van Dyke Brown' will do. But other paintings show Field Work, often in a much-romanticised version, and those are the ones that need a background showing some Furahan Biology. This one starts with wadudu. 

Click to enlarge; copyright Gert van Dijk

‘Wadudu’, as astute readers may remember, are small Furahan animals, somewhat resembling insects. If not, see here and here. Some wadudu may be communal species and build their own living arrangements, like termite mounds. Some early doodles of possible wadudu castles are shown above: these are ‘Mark I Castles’. The sketches show roof-like outcroppings or ridges along their surface, with a vague idea that they could protect the structure against the sun, or perhaps against rainfall or even snow. Termites are limited to hot regions, but there is no reason to apply that rule to wadudu castles too. 

Click to enlarge; copyright Gert van Dijk

I made a quick colour sketch of one design, shown above. This ‘Mark II Castle’ is not that different from a 'Mark I'; it has an elongated shape and is bilaterally symmetrical. The narrow side points towards the sun during the hottest times of the day, to limit the surface area that is directly insolated. The rootlike structures running along the ground are hollow cylinders that function as highways allowing the beasties inside easy access to wherever they need to go. Different castles may be connected by such cylinders, both on the ground and below it, allowing communities to link up and form even larger superorganisms. The overhanging roofs were smooth and white, to reflect sunlight and to protect the castle from heating up too much. 


Click to enlarge; From Claggett et al. J Struct Eng 2018; 144: 02518001; DOI: 10.1061/(ASCE)ST.1943-541X.0002043

The wadudu would have to produce different materials for that to work, so I had a look at Earth's termites. It turns out that termite mounds can have very different shapes (see above). The paper I copied the images from (Claggett et al DOI: 10.1061/(ASCE)ST.1943-541X.0002043) differentiated between conical, dome, cathedral, mushroom and meridian or compass mounds. The differences depend on differing circumstances and requirements to control temperature, humidity and ventilation. 

Click to enlarge; Oberst et al. J R Soc 2021; 18: 20200957;

It runs out that termites indeed alter the soil they use to build their mounds with. Termites use grains of sand or other materials and saliva to form 'boluses' that are then cemented together. They may use coarse granules in the centre of walls, and finer ones for wall surfaces. The termites can even mix clay in the boluses to provide water-resistant walls. With all this going on, it would not be a stretch to provide Furahan wadudu with equal or better capabilities to produce different materials, from watertight layers to highly reflective ones. That opens up some really interesting possibilities, so I think I will return to wadudu castles in the future.

The bilateral symmetry of the Mark II may not have been optimal. For most places on Earth, the sun will never be directly overhead. The axial tilt of Earth ensures that the sun will generally be towards the South if you are on the Northern hemisphere, and vice versa. This means that a sun shade does not have to be symmetrical in the North-South direction. The smart way would be build a shade that is angled in accordance with the direction of the sun, something that will depend on the latitude (and the rotation of the planet's axis). This is very similar to the way solar panels are positioned. Solar panels absorb light, but the shades should reflect as much of it as possible. They should be smooth and as reflective as possible; a glaring white would be nice. Depending on the climate, the nights might be cold, and in that case part of the castle could welcome the sun's rays early in the morning. That part could even be dark so the castle can warm up. The structure at the opposite end would catch the last rays of the setting sun, so you might think that the castle could do with some warming up before the night. Possibly; I assumed that the castle would warm up during the day regardless of the shades, so the roofs may need to protect against the evening sun too. The roofs could bend down towards the direction of the setting sun to do just that.  

Click to enlarge; copyright Gert van Dijk

Click to enlarge; copyright Gert van Dijk

I sculpted such a Mark III castle in ZBrush: here it is, shown from several points of view to highlight its asymmetrical shape. Instead of one roof, it has several. Imagine that it is about 3 meters high. The roofs should be white, whereas the rest of the structure will probably have the colour of the sand it is built from. 

The videos above show such a castle. Unfortunately, I could not colour it correctly for the video. I wished to show how it looks while the sun moves from sunrise to sunset in one smooth movement, but that did not work well. I had defined a few positions for the sun, but the software treated them like stops on a train ride: the sun now reaches a place, stops ('all aboard!') , and departs for the next place. I should do it again, but the point was to produce a painting, not a video. And I can now paint that background.
By now you will probably be wondering what the castle builders look like. Actually, I don't know yet. I haven't yet decided whether they the castles are built by wadudu, spidrids, or by another group altogether. Shouldn't I have decided that before I designed the castles? I think not: I doubt that anyone could deduce termite anatomy by studying a termite mound, other than that the builders are small, can move grains of sand around and stick them together. That'll do for now.

Thursday, 29 April 2021

Zoom interview with Dougal Dixon tomorrow

 I received, courtesy of Dougal Dixon, an invitation from Oscar Salguero, a book curator from New York, to view a Zoom presentation given tomorrow by Dougal. Mr Salguero assured me anyone can register for free. Because time is short I will just pass on the information.


 "Mr. Dixon will give a live presentation highlighting some of his most important works on speculative zoology from the last 40 years. This will be presented via zoom and it's sponsored by the Center for Book Arts in NY."

 Friday, April 30, from 1 - 2:30pm EST

That should make 19:00 -21:30 hrs CET, and 18:00-20:30 hrs for people in the UK  

 Here is the event (click on "Register" button to receive the zoom link):

Facebook page:


 After the event

 This is just a short update for those who are curious about Dougal’s work.

In the talk, Dougal mentioned that there would be a 40-year anniversary edition of ‘After Man’, that should be published before the end of 2021. I understood that it will have more material than the books published so far, including sketches.

Another interesting bit of information was that there were Japanese model kits of some of the creatures featuring in ‘After Man’. Dougal showed a box with content of an unassembled kit of the Night Stalker. I was curious and wondered if I could find out more about those kits (secretly hoping I might still order one from some forgotten Japanese warehouse).


Well, I found two entries on a site of a company where you can indeed order such things, but the items were sold out. There were a few images, and I chose the one above, because it showed the contents of the box.


The two images above are were posted by a collector on a site called ‘dinotoyblog’. Interesting, aren't they? Alas, I found no hidden stores of such models...


Thursday, 22 April 2021

Terra Ultima by Raoul Deleo

 A friend called my attention to an art project she had read about in her newspaper, and she thought I would like it. I certainly did and decided to write about it, even though it is not a typical speculative biology project. The project is much more about the art than about science, and has a strong poetic quality. But foremost, I think, it is work of extraordinary quality.

The project is called 'Terra Ultima'. There is a nice site showing quite a few paintings, as well as a Youtube channel, with some videos showing the artist at work. The background story is that the artist, Raoul Deleo, has visited the continent of Terra Ultima several times and came back with the sketches of its wildlife to prove it. 

Here is a nice video showing the background story. Raoul lives only about 35 km from where I live, has been working on his project since at least 2015, but I managed to remain completely ignorant of his work until recently. I was just in time though, as a book about the project has just been published. In case you are interested you should know that at present it is in Dutch only, but Raoul told me that a French version is already in the works, and English-language publishers have already showed an interest. Let me just jump in and give you some examples.          

Click to enlarge; copyright Raoul Deleo

The 'Pallid Octopossum' (Octopossum leucostolum). I chose to start with this one, because terrestrial cephalopods are a Big Thing in speculative evolution. A long time ago, I argued that the tentacles of walking octopuses (yes, I know about the plural 'octopodes', but this sounds better) would turn into legs with joints (here is the first post of a sequence; to find the rest, just type in 'walking with tentacles' in the blog's search window). The arms need not evolve a skeleton if they mostly have to deal with tensile rather than compressive forces, so a brachiating animal might still have tentacles (or a cernuating one). This cute fellow's furry tentacles would fit the bill.

Before anyone starts complaining that this animal cannot possibly have evolved either from a cephalopod or a mammal, I agree. The combination of fur, external ears, a long probably sticky tongue on the one hand and tentacles with suckers on the other tells us that this animal is a composite.

Regular readers may remember that I had my doubts about the 'mix a monster' approach used in the film and game industries (examples here and here). At the time, I concluded that that was one of the defining differences between the worlds of 'speculative biology' and 'creature design': the first frowns upon approaches that are contrary to science, whereas the second couldn't care less, as long as the results looks cool and sells. I try to limit my protesting against a lack of scientific rigour only when people make unjustified claims about scientific quality (I am a scientist; that is what we do!).

Click to enlarge; copyright Raoul Deleo

A gecko! Sort of anyway (Erminogecko mollidactylus). It is a hexapod! There's fur, external ears again, three pairs of legs with four toes each, so this animal is also a composite. Have a close look at its potential prey. In an interesting twist, this creature has one pair of membranous insect-like wings, as well as two bird-like legs, and camera eyes, not compound ones. It is almost the reverse of the geckoid, so the illustrator is letting the viewer see that he knows what he is doing, and that the mixture is part of the fun.

There is probably a third school of 'design an animal', and this particular one is probably much older than creature design or speculative evolution: it is 'animal fantasy'. I guess its ancestry includes the fantastical animals bored mediaeval monks drew in the margins of their books, as well as the beings Hieronymus Bosch painted to make people scared of Hell.

Click to enlarge; copyright Raoul Deleo

A 'lieveheersbeertje' (Coccinellursus hexapedus). A 'lieve-heers-beest-je' is literally a 'Good-Lord's- beast-diminutive suffix'. That's Dutch for ladybug. A 'beer' is a bear, so the name is a nice pun combining 'ladybug' with 'bear'. I wonder what the translators will do with that; do any readers wish to take up the challenge?

The animal is again a composite hexapod. Fantasy animals mostly have to look good, and does this one look good! I really must work on my own fur painting skills. Have you noticed that the animals are all posed in such a way that their anatomy is well visible, without awkward foreshortening and with good lighting, so there are no shadows obscuring part of their shape or colour? That style reminded me of James Audubon.

Click to enlarge; copyright Raoul Deleo

Here I put together Raoul's 'Flamingo fawn' (Phoenicopterus cervocephalus, which conforms to 'deer-headed flamingo') next to Audubon's flamingo. Look at how the head is turned around, so the shape of the animal just fills the available space. Raoul confirmed that Audubon was a great inspiration, so that explains part of the atmosphere of these paintings. 


Click to enlarge; copyright Raoul Deleo

The 'sheen green harefly' (Libellula lagoformosa). An insect-mammal composite showing a wonderful mixture of forms and colours. I cannot help wondering how it would fly, with those four wings at its very top. I guess it might look a bit like a tetrapter in flight, although the harefly obviously has bilateral symmetry. 

Click to enlarge; copyright Raoul Deleo

The 'headwinged penguin' (Pygoscelis cephalopterix). Humour is one of the best ways to avoid people taking your work overly seriously, and Raoul's work is suffused with a mild humour. Penguins look charming to begin with, and equipping penguin heads with functional (!) wings puts the work into the proper perspective, I think.

Terra Ultima is a charming and very entertaining animal fantasy. Even if you prefer a diet of rigorous scientific speculative evolution, the Terra Ultima site is definitely worth a visit, if only to be inspired by the extremely skilful paintings.     

I have already ordered the book, and will keep you informed on this blog when there are versions on other languages.     

Sunday, 7 March 2021

Explaining and animating how cloakfish swim

In the two previous posts I wrote about parts of The Book that provide background information about how animals move on Furaha. There will be four double-page spreads showing such themes in The Book, about rusps, spidrids, tetrapters and cloakfish. 

I thought the cloakfish one would be easy, until I decided that it was high time I also made some progress towards a short CGI documentary I wrote about earlier, the one with cloakfish biodiversity as its main subject. That is a very big job and it is quite possible that I will fail on the programming side. But nothing ventured, nothing gained, so I went ahead and put some hours into Matlab programming. My strategy to design diverse cloakfish is to write editors that allow shapes to be designed with ease. The programmes then proceeds to make ‘3d meshes’, the basic working material for 3D design. How to get from meshes to nice photorealistic images is another story altogether. 

Click to enlarge; copyright Gert van Dijk

These are the editor screens. The user places control points here and there, which are then connected by a spline function. This results in nice smooth curves, useful for organic shapes. Panel A shows the body designer with a default shape. The inset shows a separate window controlling cross-sections of the beastie. By changing both shape and cross sections interesting forms can be produced. Panel B is the cloak editor. Apart from determining the shape of the cloak it also allows control over cloak movement, such as number of waves, wave amplitude, cloak curvature, thickness, etc. Panel C does something similar for the four front fins, and panel D shows the resulting output for the default shapes. 

Click to enlarge; copyright Gert van Dijk

With a few minutes’ worth of tinkering, you get this relatively slender cloakfish, probably a reasonably fast swimmer. 

Click to enlarge; copyright Gert van Dijk

Or this short and bulky ‘short-sleaved cloakfish’.

Click to enlarge; copyright Gert van Dijk

Or even this highly derived cloakfish, in which the cloaks are no longer ribbons, but shaped like penguin wings. They function in much the same way. 

 But the main point of this post was to show how the cloaks move. To do that, I had a look at the literature, and I found some papers on knifefish, but to my surprise more papers about artificial robot fish with similar fins. Apparently, people all over the world are working on robot fish, which is nice. Less nice is that some work at defence institutes, so what are they preparing for? Killer fish robots? Must we really? 

Click to enlarge; from: Liu, Curet. Swimming performance of a bio-inspired robotic vessel with undulating fin propulsion. Bioinspir. Biomim. 13 (2018) 056006 1748-3190/aacd26

Anyway, here is an example of robot ribbon fin design. The artificial cloak design followed exactly the same reasoning as my virtual cloakfish designs. Such papers make a distinction between ‘oscillation’ and ‘undulation’. If a cloak, ribbon or fin swings side-to-side as a whole, the word ‘oscillation’ is used, and when waves travel along the length of the cloak, it is ‘undulation’. But the distinction is not all that clear; it depends on the number of waves travelling along the cloak. If there is less than one wave on the cloak or fin at a time, then the movement largely concerns the fin as a whole, so the movement edges towards oscillation. Here is a YouTube film explaining the difference

Pure oscillatory sideways movement are useless, because they do not propel the beast forwards. The animation above shows such an almost pure sideways movement of the cloaks. The movement would push water away from the cloak, resulting in a force towards the attachment of the cloak (the ‘dagger’). In knifefish, with just one cloak underneath the body, this force ‘heaves’ the body up. With four cloaks, the dagger will not be going anywhere, so this is just a waste of energy. We want water to be pushed backwards. The cloaks push water backwards when its parts are at an angle to the direction of movement. These parts produce forwards thrust. 

Let’s equip our default cloakfish with exactly one wave per cloak. One half of that wave will be angled towards the left, and the other half towards the right. Both produce sideways forces, but these should cancel one another out. The robot designers reported that the robots swam nicely with just one wave per cloak. Mind you, the robots usually had just one cloak, like the knifefish. 

The animation also shows one other trick: if you look closely, you can see that the cloaks do not sway much at front, and the amplitude of the wave increases towards the back of the animal. I borrowed that from real biology, as at least rays and knifefish do this. 

Let’s now equip our knifefish with 2 waves per cloak. The parts of the wave that are useful for swimming are now at a steeper angle towards the direction of movement, nearing perpendicular to it. I thought that this should increase the propulsive force a lot, but work on the robot fish did not agree. The velocity did not increase much, but the robot was more stable, which is intriguing. Real knifefish have more than two fins on their ribbon fins at one time, so there must be an advantage in that. 

Click to enlarge; from: Blevins, Lauder. Rajiform locomotion: three-dimensional kinematics of the pectoral fin surface during swimming in the freshwater stingray Potamotrygon orbignyi.  The Journal of Experimental Biology 2012; 215, 3231-3241

This image is from a paper about ray fin movement. The fins as a whole move up and down (so they oscillate), while there are ripples along the edges of the fins (so they also undulate). Nature seems to like combinations better than separations. The edges of the fins curl up and down, so they do not move as if there are completely stiff rays in them. 

I decided to build that in too, so here is a ‘curly-cloaked cloakfish’. I like it. One odd thing about these cloakfish animations is that it is not immediately obvious how they work, when you see the movement. It is also not easy to find an angle, when you rotate the objects, from where it is easy to get an immediate overview just how the animal is built. That can be seen as a disadvantage, or, in reverse, as an advantage, because it underlines that we are looking at an alien shape. 

By now, cloakfish ‘evolution’ has progressed to allow a variety of body and cloak shapes. Shapes range from ‘long-sleeved’ cloakfish with long narrow ribbon fins with multiple waves along their surface, to very short star-shaped cloakfish with narrow wings that fly through the water. That is certainly enough material for two explanatory pages in The Book, and should be enough for a short documentary too. But that will depend on me improving my skills as regards merging and smoothing 3D meshes.

Friday, 5 February 2021

Explaining Spidrid walking

 This will be another fairly short post. In the previous post I explained that I was working on pages for The Book that explained some biomechanical tricks of Furahan lifeforms. Other such explanatory pages deal with things such as rusp snouts and gaits (done), photosynthetic spectra (done), cloakfish movements (to be done) and spidrid gaits (done).

I will not show the actual spidrid illustrations, but can show you some of the underlying thoughts by way of animations.  I used the programs -all Matlab- to produce such animations to choose a single frame, which I then rotated this way and that until I was pleased with the composition. The resulting image was then imported into Corel Painter and used as the guideline for a digital painting. But I will not show these here.


The first animation shows your typical run of the mill garden-variety spidrid. It is walking slowly, meaning that each leg is on the ground for one half of the walking cycle. With eight legs, it is easy to have enough legs on the ground to provide a stable support platform at all times. The ‘support diagram’ is a polygon connecting all feet that are on the ground at any one time.

The gait used here is what I call an ‘alternating ripple’. Imagine that the legs are numbered 1 to 8, going round the animal. If the phase differences are 1/8, 2/8, 3/8, up to 8/8 in the same leg order, then legs that are close in phase would also be close in space, so many legs on one side of the beast could be off the ground at the same time, so it would tipple over. So, we introduce an additional offset for even-numbered  legs: 1/8, 5/8, 2/8, 6/8, 3/8, 7/8, 4/8 and 8/8. You will probably need some graph paper to get to grips with all this...

The red lines show the path a legs traces in 3D space. Because the ‘camera’ follows the body, the tracer paths are also respective to the body. The effect is like that of the animal walking along on a treadmill.  

The second one is very similar, but the main difference is that the legs are on the ground for less than half the time. Such schemes are typical for fast movements. The animation runs at the same number of frames per second, so you cannot appreciate the speed difference. There are fewer legs on the ground at one time. The polygons of the support diagrams have now morphed into lines or even points, if there is only one leg on the ground.       


Now we move to a more specialised racing spidrid. The camera no longer moves along with the beastie, but is fixed in space. The animal has relatively long legs, and runs the risk of knocking them into one another. That has to be avoided by reducing stride length a bit and adapting the gait: adjacent legs should not be at opposite phases in the cycle, as they then will certainly knock into one another. This one is using the ‘slow’ leg pattern at which a foot is one the ground half the time.   

This is the same racing spidrid at high speed. Each leg is now on the ground for less than half the time, more suited to fast movements. The animal changed its gait in two ways: the first is that the phase differences between legs are smaller, and arranged in such a way that at times there is no leg on the ground at all. It is effectively jumping! The second change is that the leading leg could only contribute to forwards movement by powerful and fast flexion movement, and I decided that the flexion muscles are relatively weak, so the animal simply lifts that legs into the air. (It should really move the body up and down as well, but the animation was not designed for complete realism.)

Many of the principles here are quite common for earth animals: walking faster is often achieved by increasing cycle frequency, stride length, reducing the fraction of the cycle that a leg is on the ground and adapting gaits to achieve jumps. Most mammals and reptiles always use all four legs at all speeds, with a few exceptions (kangaroos, probably hadrosaurs; no doubt there are more). But these poor unfortunate creatures have to make do with only four legs anyway, leaving them little choice. Earth crabs do have choices, and when they speed up, they actually use fewer legs, down to just two. Spidrids, not to be outdone by Earth creatures, have similar tricks up their virtual sleeves.