An aside about rusp insides (Archives IVb)

This post is an additional one: having decided that rusps must have an endoskeleton, I started wondering what its structure might be, and here are some sketchy results.

Click to enlarge; copyright Gert van Dijk

In principle rusps have segmented bodies, just like Earths arthropods and vertebrates. But just like those animals on Earth, that basic structure is no longer visible in all aspects of their biology. In the rusp case the skeleton still shows strong evidence of segmentation. Each of the twelve pairs of legs should carry its own portion of the animal's weight, and the skeleton should reflect that. What you see above is one segment of the middle part of the body; the heads and whips are not shown. The legs are greenish in colour, and the beige ring is the main skeleton of the body. Note the two arched bones, situated directly above the hip joints. They meet in the middle high up near the animal's back. The mass of the animal is slung underneath these arches. There is a secondary arch in the belly of the animal acting as a sort of load-bearing floor. In the back a bone extends forwards and backwards, joining the segmental rings together in the form of a 'dorsal column'. The ensemble looks suspiciously like a vertebral column with ribs, but appearances are deceiving! In vertebrates, ribs are suspended from the vertebral column and do not transfer the weight of the animal to the legs. Instead, these rusp arches function exactly like arches in architecture, and transfer weight to the legs.

Click to enlarge; copyright Gert van Dijk

Here you see are twelve locomotor segments together. The sort of orange coloured bones at the sides provide another link between adjacent segments on the level of the hips. There is a joint in the middle, normally held in position by strong tendons,. Their purpose is explained in the next image. The skeleton of the anterior and posterior heads is not shown, and neither are the whip skeletons. However, you can easily imagine the dorsal column giving rise to the fore and aft whips.

Click to enlarge; copyright Gert van Dijk

Here is the animal bent sideways. The orange hinge bones at the sides are pulled together on ne side and extended on the other. I suppose the animal can flex more than this, but not really that much.

Click to enlarge; copyright Gert van Dijk

And finally another possibility. Here, the main weight-bearing structure is also a curved beam, but this one sits much lower in the body. The beam again supports a central column, that now gives rise to a vertical 'mast' supporting the body. The sides are linked in the same way as previously. I am less certain how to support the whips with this design; perhaps the central column simply rises up through the skulls to form the whip skeleton. Alernatively, it could find its origin in the top of the masts.

I haven't decided which design will be the final say on rusp anatomy, and in a certain sense it is not necessary to settle on a specific design, as not all of it is necessary to paint a rusp. Then again, thinking about what makes an animal work certainly will have its effect on a painting and is likely to add details. Those details do not serve to explain everything about an animal there is to know. Instead, they make viewers think that there is more than you can see. That work best if there really is more than meets the eye...

Archives IV: once and future rusps

The archives of the Institute of Furahan Biology contain the evolutionary lineages of almost all Furahan animals, in the form of sketches that show how the animal and its depiction evolved over time, before their shapes were frozen in the form of a painting. Well, that is how it seemed: as I have started reworking my paintings digitally, evolution has suddenly leapt ahead again. Sometimes I also revisit old designs again; rusps are an example.

Click to enlarge; copyright Gert van Dijk

Rusps feature on the 'walking with rusps' page on the main Furaha site (on the 'land' page). The image above shows the first ever sketches of 'rusps'. (Their name is inspired by how Dutch children may have difficulty with the word for caterpillar, and end up saying 'rusp' instead of 'rups'.) As you can see, rusps have multiple legs and are protected by a strong carapax. My notes alongside the sketch stated whether such presumably slow animals could survive in an environment of agile large animals. But I also noted that sea urchins are bright nor fast, but do quite well. Such considerations made me add stings, evolved from stings alongside the body through poisonous hairy plumes into mean-looking fore and aft tentacles equipped with poisonous barbs. Their bodies are segmented, and there are multiple eyes on the front and back; in fact the lower rusp also has secondary eyes along the body. The reason there is a tentacle at both ends had to do with my wish to protect the animal. I have always been surprised by the inability of earth's animals to protect their rear end well, a weakness exploited with great success by predators such as lions and hyenas. Of course, this 'active rear' design, with eyes, a tentacle and the corresponding neural circuitry, represents a departure from Earth patterns, where no large animal has a 'split brain' to this degree. It reminds me of the claims for a 'secondary brain', such as was once implied for stegosaurs? Such a design goes against the theme of 'cephalisation', and I am not at all certain that it could actually work. Then again, I see no definite reason why it could not.

Click to enlarge; copyright Gert van Dijk

I almost immediately wished to make them bigger, at least elephant sized. Here is another early sketch, showing how a large rusp crosses a stream sunk into the ground. Animals such as elephants have great difficulty in doing so, as they cannot jump at all and dislike steep inclines. I thought that rusps would have the advantage of being able to use their long bodies: they can hold the front part of their body in the air at some energetic cost until they are able to find a foothold on the other side.

Rusps probably evolved from millipede-like ancestors. In contrast to Earths arthropods these ancestors were obviously equipped with respiratory and circulatory systems allowing adaptations for large bodiess. They were also endoskeletal, for similar reasons. The carapax is not a part of the skeleton, but simply an outer protective covering; it is leathery rather than hard.

Click to enlarge; copyright Gert van Dijk

The top image shows one from a low viewpoint, a trick that by itself suggests large size, as viewers often assume a viewing point at eye level. What you can also see is how the legs move in a sort of ripple, with adjacent legs moving a bit out of phase with the ones in front and behind. That is the usual gait of Earth's millipedes and centipedes, by the way (this is also animated on the main Furaha site). The sketch in the middle show transverse sections, illustrating my thoughts on their possible body shapes. I did not want their legs knocking into one another, so I thought that successive pairs could be offset to the left or the right, giving each room to move. To evoke an atmosphere of large size, I played with the idea of making them high and narrow rather than wide and squat. If you take a good look at elephants and many dinosaurs you will see that they are often relatively narrow. I also played with the site of attachment of the legs: underneath the animal or along its sides? The sketch at the bottom shows a resulting rusp of the narrow type. I rather like their tentacles, but realised that they woud pose biomechanical problems: holding them horizontally with muscle power alone would be as comfortable and efficient as humans holding their arms horizontally in the air all day: try to do it for 10 minutes...

Click to enlarge; copyright Gert van Dijk

Rusps only made it to a painting once, a detail of which is shown above. But even on that painting they were in the middle distance. One of the reasons they never received their own painting was that I had problems in finding a suitable design. With their long horizontal bodies they present a somewhat passive shape. One solution would be to show them from the front with a considerable degree of foreshortening, such as in the images above, or I could show only a part of their body, such as in the 'fording a stream' design above. But there were other problems as well, such as the relative positions of the legs, the 'active rear' with its corollary 'split brain', and of coarse the tentacles, that cannot just be held in the air horizontally like that. For a structure held up with muscle power only, such a position is virtually impossible; just try to hold your arms with extended elbows horizontally in the air for 10 minutes, and you will find out why...

Click to enlarge; copyright Gert van Dijk

I keep coming back to rusps, and above is a recent study done with Vue Infinite. Here, too, the successive legs are offset resulting in a double track on each side. It has as a disadvantage that the hip joint is not directly above the foot. As a painting it results in a rather sedate view, but the well-lit afternoon sunshine could make up for that. Rusps ought to look grandiose, and perhaps a design like this brings that out.

The one thing I am not worried about at all is the leg pattern. The two animations are newer 3D versions of rusp locomotion. The essence of centipede or millipede locomotion is that there are successive phase differences between successive legs. Depending on whether a leg is either just ahead or behind in its cycle compared to the leg behind it, the legs tend to clump together either on the ground or in the air. The effect is that the movement appears to ripple either forwards or backwards along the animal. For centipedes and millipedes the choice seems to depend on how far sideways the legs are held. In rusps, the legs are always held vertically, so leg tangles have to be avoided in another way. Possible solutions are of course to make the legs shorter, place them further apart, or, as I wrote above, to have their feet offset. On the other hand, the animation shows that manipulating the phase differences can avoid leg entanglement quite well, so the simplest solution is probably the best one. In short, there seems to be little need to offset the legs.

Click to enlarge; From: Steven Vogel. Comparative biomechanics. Princeton Oxford 2003

Click to enlarge; from:Klein et al; biology of the sauropod dinosaurs. Indiana University Press 2011

As for the tentacles, some further thought suggested a solution. Sauropod necks and tails are very long structures held out horizontally in positions that at first glance seem impossible. This is possible because they are not tentacles but trusses: there are bones resisting compression at the bottom and tendons to withstand pulling forces at the top. With a design like that, rusps whips could function and wreak havoc on any hexapod predator foolish enough to enter the rusps' range of motion, at its front or back. Rusps whips will not curve in three dimensions as gracefully as they do in the sketches above, but will be a bit stiffer. Expect the cross section of future rusp whips to be narrow and high.

The next diversion into the archives will explain the relation between rusps and major Gruber, a creation of the late Moebius, a French grand master of bandes dessinées (comics).

A century of thoats

As post titles go, the one above may be a bad choice: it will probably only catch the attention of those who already know what a thoat is. To attract more readers I should perhaps alter the title; the second-highest rating post in this blog, as far as numbers of viewers is concerned, had 'Avatar' in the title, so I should probably learn from that. So here is an alternate title: 'Why do animals such as the thoat in "John Carter of Mars" and the thanator in "Avatar" walk in such an illogical manner?

A thoat is a large eight-legged Barsoomian animal, 'Barsoom' being the native name for the planet Mars in Edgar Rice Burrough's works. Burroughs starting writing Barsoom novels around 1912. I never read any, for the simple reason that there were no Barsoom books in translation around when I was at the right age to enjoy them. I did read his Tarzan books, though, and suppose that I would have read Barsoom novels with equal appetite. The reason Barsoom caught my attention after having ignored it so far, lies in the recent movie 'John Carter of Mars' (JCoM).

Click to enlarge; copyright Michael Kutsche

The wonderful image above is from the DeviantArt account of Michael Kutsche, who designed the thoat for JCoM; the thoat is the eight-legged beast, not the individual sitting on top. Have a look at how Kutsche approached the 'leg problem': where do you put eight legs without them looking odd, if not altogether ridiculous? Kutsche solved the problem by dividing the eight legs in front and hind groups. In build, the legs look a lot like those of a large mammal such as a rhinoceros or an elephant. In fact, the original hind and front legs were simply copied and pasted as close as possible to the original. Where there was one leg there are now two, moving in unison. Being so close together, that is all they can do, as otherwise they would knock into one another. This solution is very reminiscent of the large animals in Avatar, except for the fact that these had six legs, with just the front legs doubled. I criticised that arrangement in a previous post, thinking that it did not make much sense from a biological point of view. It felt it would be easy to learn how six-legged animals could or should move: after all, Earth is literally crawling with insects. For eight-legged creatures you can look at spiders or crabs.

The video fragments above shows a few seconds of thoats walking in JCoM (sorry about the quality), illustrating the 'doubled leg design'. Bt the way, I wonder why the legs are so immensely thick. Their thickness looks about right for an athletic elephant-sized mammal on Earth with just four legs. But with eight legs, each leg can be more slender than if there are four (read here for posts on leg design, gravity and the number of legs). As it is, the animal looks as if it was designed for a planet with a very high gravity, not for Mars, where gravity is just 38% of that of Earth.

Click to enlarge

The Barsoom fictional universe has been around for a century, so many illustrators over the years must have faced the problem how to design a plausible as well as dramatic eight-legged big animal? The drawing above, by John Allen St John, must be one of the first depictions of the Barsoom universe (I found it here). The style of the drawing fits the early twentieth century. This early thoat does not show doubling of the front and hind pairs of feet, but shows tripling of the front feet, keeping one pair of hind legs. There seems to be a generic 'copy and paste legs' solution operating here.

In the late thirties there was an attempt to produce an animation of JCoM. Only a bit can be found now, coming from ERBzine, a very large website on Edgar Rice Burroughs. I woulld like to include it here but am having upload problems; I may rectify that ater, but for now, here is the YouTube version. Look at how the thoat lands on its feet: there is a definite phase offset between the successive pairs of feet, resulting in a jumping gallop. This is one of the very few thoat designs with phase differences between successive pairs of legs.

Click to enlarge

Edgar Rice Burroughs son, John Coleman Burroughs, worked on his father's creations. He produced a wooden thoat model, shown above. I found these images on the Erbzine site. It is a pity that the model cannot be seen better. The legs are so close together on the body, that they must all move in unison on one side of the body, or else they will knock into one another.

Click to enlarge; copyright Frank Frazetta (I presume)

The late Frank Frazetta, famous for his equally but not similarly well-developed heroes and heroines, produced quite a few Barsoom paintings. I found no thoat among them, but there are two banths, Barsoomian lions with ten legs. The ink drawing above shows a banth from the front, a nice trick to avoid looking too closely at its shape. The legs on one side seem to be moving in unison. For the oil painting, Frazetta chose to hide most of the banth's legs from sight. For a painter of Frazetta's skill this is probably no coincidence; did he feel that showing all legs would not work?

Click to enlarge; copyright William Stout

The image above is by William Stout, a well-known painter of palaeontological scenes. His thoat is livelier than most, as can be expected from a Stout design. And the legs? Well, a doubling design again.

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So, what can be concluded from studying a century of thoat design? Some of the best fantasy illustrators worked on the problem, and many gravitated towards the same solution: they doubled or tripled pairs of legs, and as such did not depart too much from the familiar mammal pattern. To me the 'doubling solution' does not seem like a good idea, but if all these wonderful illustrators chose it, I may have been too harsh in my judgement. A good artist or illustrator will have learned human and some mammal anatomy, but that education is not likely to include hexapod and octapod locomotion. In fact, the necessary knowledge is not that easy to find, and has not been adapted for non-specialist use.

Copyright Gert van Dijk

What would you get if you do take such knowledge into account? Well, probably something as in the animation above (adapted from a model designed to study Furahan rusp locomotion). I made no effort to define the body and the legs all have the same shape. The main point was to show an eight-legged gait that can work well. The gait is based on one described in a scientific paper on spidr gaits, and concerns a slow walk. I applied that gait to a model in which the legs are held vertically rather then horizontally, making the design better suited for large animals. Personally, I think it makes more sense than the doubling design.

You could argue that using such a true octapod gait or the simpler 'doubled leg gait' does not matter, as the audience will probably accept doubled legs as easily as a more sensible gait. Maybe; the audience may also feel that the true octapod gait has a more alien feel to it, and that should please the designers. All in all, I probably overestimated how accessible the required biological knowledge is. Well, that is a good reason to continue this blog. What else could be done with it? Phone Hollywood, perhaps?...

Four years on (and back again!)

Four year ago, almost to the day, I started this blog about Furahan Biology and Allied Matters. Over time, the 'allied matters' took precedence over Furahan biology, but the readers did not seem to mind too much. Last February I decided to take a break from blogging for a while. I had found that writing an entry every two weeks was beginning to feel a bit like a load. I think the sabbatical worked, but even I will only know when I start blogging on a regular basis again. I have several interesting subjects in mind, such as animal legs in the recent 'John Carter of Mars' movie or about the colour of plants.

So, what happened to the Furaha project in the last year? Well, I produced several double page spreads. Two dealt with Fishes IV and Fishes V, with five new digital paintings. One spread dealt with a new animal, the 'dandy', a tree dweller with a colourful asymmetric giant claw. I produced three spreads without life forms: two showed the outer and inner planetary systems of Jua (that is the star Nu Phoenicis), and one shows a large atlas-like map. No doubt you would like to see these paintings, but that is not going to happen. After all, all these pages are meant for a 20 to 26 page 'proof of concept' booklet that I can show to publishers, as I wrote last year. The pages look like the sample I showed earlier, right here. My sentiments are that if I cannot sell the idea to a publisher with a worked-out and carefully edited sample like this, I cannot sell it at all. We'll see.

Of course, some pages show older, non-digital work. These do not remain untouched, however. I will show a few images of a work in progress: the prober and bobbuck page. I have no problems with showing it, as you are already familiar with the painting: it is the one at the top of this blog. That image was taken from a photograph; it is remarkably difficult to take decent photographs of paintings: even with digital cameras and tripods the colours are often incorrect, they are not sharp, or not sharp everywhere, etc. To solve that I had all my paintings scanned last year. As some of them are 50x70 cm that required finding a professional scanning service, but it was worth it. I know have digital versions of about 175 dots per cm (120 dots per cm equal 300 dots per inch).

Click to enlarge; copyright Gert van Dijk

Here is an example: this is the head of the prober, taken from the high-resolution scan. Enlarge it to see it at full resolution. The width of this section corresponds to about 65 mm on the real painting, so if you think my painting is rather coarse, take that into consideration. I could of course simply use the scan as such, but I prefer to take advantage of the possibilities that digital painting affords. One reason to do so is that I never considered the biological backgrounds of these creatures when I painted them as thoroughly as I discuss biomechanics in my blog these days. To a large extent the themes developed as I went along, meaning there are some oddities here and there (Well, lots of them, really. For instance, felt that the bobbuck's torso was too short, and that the middle pair of legs would benefit from an idea I developed later: they are further apart than the front and middle pairs. Having painted quite a few Fishes recently, all of which have four eyes, I started wondering why terrestrial hexapods would have lost their lower pair of eyes. Instead, I decide to migrate this pair sideways, giving terrestrial hexapods four eyes. This creates opportunities for visual specialisation as well. I also felt that the eye design need not always involve eyes on stalks, so in may cases the stalks could go.

Click to enlarge; copyright Gert van Dijk

So here is a first step towards the revised painting 'Prober and Bobbuck Mk II'. I selected the animals gave them their own layer, and filled in the background layer roughly. As you see, the bobbuck has already been dissected, and its parts have been rearranged. The eye stalks have gone and the prober has been given a tentative set of new eyes.

Click to enlarge; copyright Gert van Dijk

This is the next stage; the bobbuck's body has been filled in tentatively. Since then I have been thinking about the relative positions of the two animals, but the original one turned out to be best. I will probably alter some more details and smooth some of the brush strokes, but I will have to be careful not to overdo it. Brush strokes have their own charm, and I should be careful not to ruin that by taking the digital element too far. I wonder whether I should revise the prober's beak to include teeth, following a discussion on the bulletin board of the Furaha site of the last few days.

Animals like the prober use their clubs for the heavy work of dismembering a carcass. They have internal teeth and jaws to grind lumps of food, and use their mouths merely to get food inside them. That's why their mouths are like beaks. Still, teeth-analogues are part of their ancestral make-up, and perhaps some tearing and cutting implements would be handy. And so it proceeds...

Away until back...

After almost four years of writing posts for this blog it is time for a sabbatical. There are certainly enough subjects left to write about. For instance, there is the issue whether established echolocation can prevent eye evolution taking off (I think not), as well as more on eyes, issues on flight, on camouflage, etc. I find writing posts and interacting with those who react (thank you all!) most enjoyable. It is just there are things I need to take care of, and the blogging batteries need recharging. I do not know when I will resume writing, but a nice time to do so would be sometime around the blog's fourth birthday (that's in April, in case you wonder). That is not a definite promise though.

This does not mean that the Furaha project is in any danger. After 30 years I am not going to drop it now. Far from it, in fact: I intend to devote part of the time I have spent blogging on painting. There's lots of things to do.

As proof that the project is very much alive, I can tell you that Furaha will appear in a film that you can actually see in a cinema. The film is being produced by an independent company and is being shot right now. I cannot say too much about it, but it is not a documentary; it will be about people, right here on Earth, and the Furaha project plays a very interesting role.

The producer recently asked me to make -with two days notice, but such things always seem to work that way- a 3D model of my woolly-haired shuffler, an animal that they had seen in my newspaper interview (here and here). and so I loaded Sculptris, a program I wrote about earlier, and started making one. Sculptris is completely free and a joy to work with. The resulting model is certainly not perfect, but for someone like me with limited experience with digital 3D sculpting programs it did not turn out too bad, I think. Particularly if you consider that this was done in about four hours of time...

Click to enlarge; copyright Gert van Dijk

Here are some screen shots of Sculptris with the model in various colours. It was a bit difficult to get the lateral jaws in there, as Sculptris does not formally accept holes. What i did was to push two extrusions together and then I flattened them where they toch one another. Formally, there are no holes in the model...

Once I had that, it wasn't difficult to export the model to the 'obj' format, import it into Vue Infinite and make a 'turn table animation'. That is what you see above. Not too bad, is it?

With the 'obj' model at hand, I decided to have a better look at a website I had visited before. The site, by the firm 'Shapeways', provides a service through which you upload a 3D computer model, and they then check it, print it in 3D and ship it to you. The instructions on how to check the model and upload it were fairly straightforward, so all was left was to choose a material. You can choose various materials with different qualities, such as the ability to hold detail. I chose a material that promised to allow details and settled for a small size, as you pay for the volume of the material used.

Click to enlarge; copyright Gert van Dijk

The model arrived within in two weeks and looked good. Part of the left maxilla had broken off, not too surprising if you consider how thin it was. The website has lots of information on how to prevent making your models too thin. What I had not foreseen is that the material was transparent, so much of the detail did not show up. I painted it to solve that, and photographed the result. Interesting, isn't it? I was impressed with the details, but would like a larger size next time. You pay for the volume of material that goes into the model, so I will have to learn how to hollow out the model; if I manage that, I should be able to order a much bigger one for the same price.

So, it's off towards the sunset for me, for a while. I intend to keep on replying to questions here and on the Furaha bulletin board in the meantime, so I'm not away altogether.

The eyes have it!

I guess almost everyone who designs fictive alien life forms want them to look truly 'alien': you want your animal to have something that tells the viewer that this is an original; it should look unearthly and yet as if it ought to look that way. The word 'alienness' is perhaps grammatically correct, but lacks punch; something like 'alienosity' might do the trick...

Frivolity aside, striking a balance between oddity and plausibility is difficult. Darwinian evolution tends towards optimisation, which in reality means the optimal balance between function and cost; economy of design pervades everything in biological evolution. As evolution on Earth has been following that path for quite some time, it is not easy to come up with strikingly different designs that work at least as well as familiar ones.

Doing away with eyes is such a major departure from 'earth standard', increasing alienosity significantly. Imagine sightless animals with otherwordly senses, pinging your innards with sonar or recognising you by the thermal pattern of your warm throat, your cold nose and old hair. Yes, sightlessness fits the bill nicely. But can you do away with eyes? I think not, except under very special circumstances. I will try to discuss why 'the eyes have it', and this will probably need more than one post. The present one will deal with probably the most famous sightless speculative world: Darwin IV by Wayne Douglas Barlowe.

Pronghead from 'Expedition';click to enlarge
Copyright 1990 Wayne Douglas Barlowe

Let me start by stating my admiration for Mr Barlowe's painting skills. The pronghead, show above, works great against the background, and the fact that is half lit works compositionally and also highlights the luminescent spots nicely. I have said it before: I wish I could paint as well. Darwin IV is presented in his book 'Expedition', available from Amazon. A television documentary with computer generated graphics is available as well.

'Eosapien' (fragment from larger painting).
Copyright 1990 Wayne Douglas Barlowe

The picture here shows some ballooning animals floating away in the darkness (they are called 'eosapien', but I suspect that that is a mistake caused by the idea that the 's' in 'sapiens' denotes a plural, but it does not -the plural would be 'sapientes'-). The luminescent spots are well visible on these animals as well as on animals in the distance. Perhaps the latter ought to be less conspicuous, seeing that the eosapiens are predators.

There is an explanation in the beginning of the book 'expedition' explaining why animals there have no eyes. The idea is that the planet was covered in thick fog for very long periods, so that vision as we know it was pretty useless during that time. Animals accordingly developed other senses: apparently there is a pressure-sensitive lateral line system, but not much is known about it. Also stated are the ability to use sonar and infrared, and the latter one is the subject of this post. The infrared sense is apparently located in 'tiny infrared receptor pits'. When the atmosphere cleared up later, these alternate senses were so well developed and entrenched that vision did not have much chance: the first stages of eyes would be poor, and would not convey an appreciable advantage to their owners, so their evolution never got under way. As defences go, this is an ingenious one. I doubt eye evolution would really be held back by superior senses, already present, but that line of thought deserves further thought.

First, let's discuss the heat sense, one of Darwin IV's ways of making sense of the environment. Many of Barlowe's animals have intriguing dots and stripes in glorious colours, glowing in the dark. Now bioluminescence was a brilliant idea with a high alienosity index ( I wish I had thought of that in time). However, it is rather odd for animals to have organs that produce light when there is nothing around to see that light. At first sense offering light to the blind seems a serious mistake, but the text again shows that this critique has been foreseen. It states that these 'biolights' are 'heat-radiating bioluminous spots that appear quite vivid to infrared sensors'. In effect, this means that the production of light is a side effect of the production of heat.

Electromagnetic spectrum from Wikipedia

Here we need to call attention to the electromagnetic spectrum. You may remember that the part humans can see is flanked by ultraviolet on the high frequency side and by infrared on the low frequency side. Now infrared is divided into near infrared and far infrared. Near infrared is in effect another colour, one humans simply cannot see, but which does not represent heat as such (here is a nice photography site explaining it well).

Left, visible light, right near infrared; Click to enlarge
Images from http://dpfwiw.com/ir.htm

There are many images on the internet taken in the near infrared range, 'translated' to activity in the part of the spectrum we can see (a true infrared image is useless, as we wouldn't even see that there was an image!). Many images of woods and trees show that leaves are very bright in the near infrared range, but that does not mean they are warm. They are not; they simply reflect a lot of the near infrared radiation falling on them, coming from the sun (the sun shines brightly in the near infrared range). Remember that a green leaf looks green because it reflects more green light than it does light of other colours. By the way, the images above show that near infrared travels better through haze and fog than visible light does, so having fog as part of the 'anti-eye argument' has its merits.

But do the animals of Darwin IV make use of near infrared? The text states that we are dealing with detection of heat, and that means 'far infrared'. Then again, most objects radiating heat also radiate near infrared radiation, so you could use one for the other. But I will assume true heat detection.

The heat organs on the bodies of Darwin IV's animal also produce visible light. That is not surprising: any fire produces heat as well as light, and often both effects are welcome (come to think of it, a fire that produced heat but not visible light would be pretty dangerous). Light bulbs are only meant to produce light, but are spectacularly inefficient in this respect: most of the power they consume goes into the generation of heat rather than of light. Nature, however, has managed to produce light without heat in the form of bioluminescence. That separation holds on Earth, though. On Darwin IV, you would expect evolution to be faced with the challenge of producing heat as efficiently as possible, meaning without squandering resources such as producing visible light as a side effect. Apparently evolution failed in this respect. This seems rather unlikely, as there must be metabolic ways to produce just heat but not light in a controlled manner. Our own bodies radiate heat but not light, so I do not think that bioluminescence as a by-product of heat production is very convincing.

But the production side of heat signals is not my major concern; that resolves around the reception side: how do Barlowe's animals make sense of the heat signature of other animals? As usual, there are animals on Earth making use of heat detection; the pit viper is probably the most famous one***. This involves making sense of radiation in the far infrared range, something called 'thermography', or writing with heat. I have copied some images from Wikipedia below. There is a good discussion here as well.

Thermography of a cat from Wikipedia

The main point of these images is what they are: images! An image shows you what is where in space. The more pixels you have, the more information the image can carry. An image is made by a camera, and digital cameras have a receptive surface, and the image is focused on that surface by a lens. A cheap camera might have a poor lens, with an unsharp picture, and with a low number of pixels. When better quality is asked for, lenses get better and the number of pixels increases. The above, in a nutshell, is the evolution of the eye (well, not every eye resembles a camera, but many do). Man-made thermographic images show that the radiation of the far infrared basically follows the same principles as visible light does. You can bend rays with a lens, and you can detect them with dedicated sensors. That does not hold for all parts of the electromagnetic spectrum: it would be hard to detect X-rays as they easily pass through tissues, and it is extraordinarily hard to focus them. I would not be surprised at all to find that biological chemicals are better at bending radiation in the visible part of the spectrum than in the far infrared: water bends light. But the premise of Darwin IV was that animals there are able to detect heat, like the pit viper. In such snakes, heat detection still has poor spatial resolution, probably because their heat detecting organs have no lens in them. Suppose the animals of Darwin IV started out a long time in their past with some molecule that responded when subjected to far infrared radiation. Wouldn't evolution drive that organ to become ever better at telling where the radiation was coming from? That development would run exactly parallel to the evolution of the eye. 'Normal' eyes started out that way, and recent evolutionary theory holds that eyes developed many times, in many forms, and extremely quickly too. The ability to detect heat would probably also be subject to the same optimisation process that affected normal vision, so its product would be an eye. Sensitive to other parts of the spectrum than our eyes, but an eye nevertheless...

Archival scenes III: "Here I am, on the shores of Lake L'Ambique..."

Unfortunately, real life, as it is called, at times requires considerable energy. Energy is a limited commodity and seems to consume creativity before it starts devouring other resources. In fact, I have toyed with the idea of closing this blog for a few months, with a note saying 'Away until I'm back' or something of equal intelligence.

But not yet. There is life here, and some unheard-of beasties may be encountered in the niches of the archival biotopes. I do not think I have ever shown much about humans on Furaha, which has its roots in my hesitation to even allow them on the planet. I thought they would wreck the place within several generations. After all, it's what they do. However, I decided that the project needed human interest, so I did introduce this alien species on my pristine planet. Once I got over my initial distrust of them, I did enjoy having humans around for various reasons: they could act as scale indicators, or they could be the actors in side stories about scientists arguing about animals' names and other typically human silliness.

But I never did a painting of humans on Furaha, and I do not think I ever will. There is a very rough sketch in the first ever post of this blog, and today I will present you with another sketch, only slightly less rough.

Click to enlarge; copyright Gert van Dijk

This is a pencil sketch on tracing paper, which explains why the contrast isn't that good. It also wasn't developed beyond this first approach (please do not look at the human's legs!).

As you can see, a Furahan citizen/scientist is squatting down near to a Furahan predator, a 'prober', to have a closer look at it. There is some kind of vehicle behind him; I tried to get away from the type of vehicle people might expect, and so designed a boring rectangle you could just dump anywhere as a temporary blot on the landscape. But this is about humans: apparently our hero is not afraid of the prober, which is not in line with some of the things I wrote over time. One statement held that, while humans may not be palatable to Furahan predators, the predators have not eaten enough humans yet to have learned this basic fact, so nothing keeps them from trying.

Let's assume that this person knows what he is doing. I certainly assumed so, as I modelled him on David Attenborough. The sketch probably never did resemble Mr Attenborough very much, but it did a bit more when I made it than it does now. I must hasten to say that I am a great admirer of Mr Attenborough, so this sketch was not at all meant to ridicule him. Quite the opposite, in fact. I think I was trying to imagine the very best of all possible documentaries on Furahan life. It would be one of those excellent BBC nature documentaries hosted by Attenborough. Imagine Attenborough on Furaha, with him talking straight into the camera. You will have to imagine the proper accent: "Well, here we are, on the shores of Lake L'Ambique, where we just happened to come upon this extraordinary animal..."