Saturday, 20 April 2013

Five years on

On April 22, 2008 I started writing this blog without any clear thoughts on the direction it should take or how successful it should be.  I still do not know how successful it actually is, as the niche this blog occupies is so specialised. Even though I cannot compare the blog easily to other blogs, I can show you some results of the last five years.

A few days ago the count stood at 172 posts with over 225,000 page views, 1042 comments and 131 followers. This results in a mean number of page views per post of 1303. Most views last less than 15 seconds, so most viewers probably people leave the page after a quick glance, which is to be expected. Every now and again someone spends 45 or 90 minutes, though, and old posts keep on being read. I will show a number of lists to illustrate how viewers behave.

First, here are the 10 most-visited posts preceded by the number of page views:    
  1. 6565 Swimming in Sand 1: the Sandworms of Dune /  Feb 2011
  2. 3113 Warren Fahy's "Fragment" / Aug 2010   
  3. 2814 A century of thoats / May 2012
  4. 2544 Avatar's 'Walking with hexapods' or 'Don't walk this way' / Feb 2010
  5. 2529 A future book on future evolution from France / Nov 2011
  6. 1451 "A Venusian Bestiary", in Which Greg Broadmore Ill... / Apr 2011
  7. 1408 Future evolution in Brussels / Feb 2009
  8. 1353 How many legs are best for megamonsters?  / May 2011
  9. 1345 Ballooning animals and Newtonian fitness / Jul 2011
  10. 1312 How much more Speculative Biology is there? / Mar 2009
The list suggests that a post may become popular for three reasons: in some cases a large spike in views was generated when a large newspaper drew attention to my blog (Der Standard from Austria). Referring to popular films (Avatar), books (Fragment) or well-known names (Greg Broadmore) seems to help, and finally key words such as 'future evolution' and 'speculative biology' draw attention. Still, there are two 'biomechanical' posts with some hard science in the list. When I started doing those I wondered whether people would skip them. Apparently not; good!

Here is a list of the most often used search terms resulting in people being referred to my blog:
  1. 1122 speculative biology
  2. 612 future evolution
  3. 566 dougal dixon greenworld
  4. 262 furahan biology
  5. 210 cladogram
  6. 204 henders island
  7. 200 planet furaha
  8. 197 bobby chiu
  9. 190 creature journal
  10. 190 furahan
There is a definite interest for Dougal Dixon's Greenworld, so I hope it will see an English version in addition to the existing Japanese one. I was much surprised by 'cladogram'. When I use 'Google images' to find out how that word leads to my blog, a familiar cladogram appeared on the second row. Someone has copied Evan Black's Nereus cladogram from my post here to his own blog (here), with a clearly stated reference to my blog, so that is all right. I can only hope that that roundabout route also led people to Evan's own Nereus page

There was also some bad news: my posts were copied verbatim on someone else's blog. I am at present busy with having these posts deleted through Google, citing a breach of copyright. That seems to be working well. I will not provide links to these blogs; these people are stealing page views from my blog, so I certainly will not direct attention to them. Away with parasites!

Click to enlarge; copyright Gert van Dijk

That's enough about the blog. I have not done much with the main Furaha site, as I spent the little time I had on new digital paintings. The image above shows a study for one. I sculpted the head of an 'Ochreback Thresher' (Ira tarda) in Sculptris as a help with perspective. Its nasal horn can be used to ward off predators, but is also used in intraspecies conflicts. The horn fits under the opponent's parietal shield bosses, meaning the combatants obtain a lock on one another in which the one with the most stamina wins. The ridges on the side of the face are meant to protect the eyes (four, not well visible) from damage, but loss of one eye in dominant individuals is not uncommon. The painting will not show such a combat, by the way.

I will end with some good news and a question. I produced a 20-page sampler of The Book and have finally started sending it to publishers! I hope one will be interested, but do not dare expect much. After all, the book is as specialised as the blog, so the potential readership might be small. In my covering letter I wrote that it should appeal to people who like science fiction art and biology. If you have made it to the end of this post, you must be one of the interested people. Is that a good description of the possible readership? Is there a better one?  

Epilogue, May 2, 2013

After the post was published I noticed a surge in page views. The source was easily identified: the Austrian newspaper 'Der Standard' had published an article about the post above, in which I had drawn attention to the fact that their earlier messages had resulted in clear spikes in the number of page views concerning the posts they had drawn attention to. Confused? You may be after this epilogue, because their article not only resulted in a spike in views of the post 'Five years on' (the one you are reading now), but also in the posts already in the top ten. The top ten for the last week was:

1. 267  Swimming in Sand....
2. 239  Five years on
3. 162  A Venusian bestiary...
4. 131  Avatar, or how...
5. 91    A century of thoats    

See the list above for the links.  To close the circle of references, you may visit the article at the site of 'Der Standard'. It is entitled 'What fascinates people about fictional life forms' (but in German, obviously). You will find it here.  

Saturday, 6 April 2013

Crabs as spidrids, spidrids as crabs...

I recently realised that Earth crab locomotion resembles Furahan spidrid walking more than I expected. I may have spent too much time on spidrids or not enough on crab locomotion, as there was a lot to learn about radial walking, odd as that may sound. I found a very nice paper on walking patterns of decapod crustaceans (basically crabs and lobsters) beginning with the sentence 'Most decapod crustaceans can walk in any direction they please'. 

From: Vidal-Gadea et al. Arthropod Structure & Development 2008; 37: 95–108 (adapted)
The image above is from that paper and shows leg movements of a sideways-walking crab, a forwards walking crab, and a forwards-moving lobster. The ability to move in any direction without turning the body is one of the main features of a radial walking design, something I thought did not exist on earth. Apparently crabs, particularly forwards walking ones, are quite 'radial'. In fact, the paper uses the very word 'radial' to describe leg positions for the forwards walking crab. A peculiar convergence with spidrids is that its common name is 'spider crab' (Libinia emarginata).

video

While most crabs preferentially walk sideways, they can combine directions and walk diagonally if they so wish. The video above shows a crab that starts walking backwards but gradually adds a horizontal element until it ends up walking sideways only. (Click the link to see the source at a better quality).

video

And here is an example of a forward walking crab. Again, the original has better quality. If you look carefully you will see that the legs do not all point sideways: the front ones are angled to the front, and the hind ones point almost backwards. In short, they are almost placed and held radially around the body. Are spidrids crustaceoid or are crustacea spidridoid?

Click to enlarge; copyright Gert van Dijk

Spidrid legs, although the mere result of a thought exercise, are rather like real crab legs. The image above shows the simplified leg anatomy, say of a sideways-walking crab (or of a spidrid leg). The bottom part shows that the leg can turn forwards and backwards around a vertical hinge close to the body, movements labelled 'promotion' and 'remotion' in technical papers. Let's call that the 'body-leg joint'. The other joints, the 'intraleg joints', in spidrids have horizontal axes allowing the leg to be straightened and flexed (see the top part). There would be muscles for every joint, but I only showed them for one.

If the animal moves in the direction shown here the leg does not need  action of the promotor and remotor muscles: the power for movement comes from the intraleg joints.  If you rotate the direction of movement 90 degrees, muscle force for this leg has to come from the body-leg joint, meaning the promotor and remotor muscles.

Click to enlarge; Copyright Gert van Dijk

So what does all this mean for spidrids? Well, regardless of the direction it walks in, a spidrid has some legs parallel to the direction of movement and some at a right angle to it. The image above shows how that relates to the direction of movement and to the necessary range of motion. The legs parallel to the movement function as the legs in sideways-walking crabs, and  depend on intraleg flexion and extension, pulling and pushing the beastie. The legs at largely right angles to the movement depend on promotion and remotion. The leg in between simply make use of both sets of muscles to varying degrees. (Mind you, the word 'promotion' in crabs always refers towards the front end of the animal; in adapting it for spidrid use it must mean 'in the direction of movement', there being no front end.)

The next evolutionary spidrid twist stemmed from the idea that one of these two types of force production might be superior to the other. How would spidrids make use of that edge, while staying radially symmetrical? Before tackling that I realised I had never shown the spidrid's ability to change direction without turning. Solving that posed some interesting Matlab programming problems, but never mind, it works. I added height for fun and slanted the body a bit when the beastie is on a slope to make it look more natural.

video
 Copyright Gert van Dijk

Here it is! Finally, a spidrid that negotiates terrain and make a sharp turn. As you can see, the sharp turn calls for some interesting leg movements. With a shallow turn you would not see the changes well. So this is how real radial animals walk. By the way, should a rich Hollywood director wish to buy the concept for a film, I am available! Anyway, it is now time to adapt this standard spidrid walk to more energy-efficient gaits.

video
Copyright Gert van Dijk

The one above is built on the assumption that flexion/extension is more efficient than promotion/remotion. So, this species uses its promotion/remotion muscles to swing the legs as far parallel to the direction of movement as they will go. There are probably anatomical limits to this, so some legs still stick out at a right angle to the direction of movement regardless. The turn becomes odd, as some legs have to swing a long way to end up in their new position.

video
Copyright Gert van Dijk

But the existence of forwards-moving crabs shows that under given circumstances using promotion and remotion as the power house is feasible. The animation above has a spidrid moving its legs with a preference for positions at a right angle to the movement. This movement also calls for large leg swings when the animal changes direction. The legs bump into one another, which can be solved with phase changes, but I left it as it is for now. The anatomy of the animal is the same in all three variants, which may be unwise; I can see the last type having shorter legs to improve leverage, at the cost of stride length.

So there we are! Rampaging spidrids! What else is left for spidrid movement? An obvious additional adaptation would be to include slanting, but I will not provide an animation of that; what you see here was quite complex. Then again, I now have a program resulting in 3D coordinates for any part of a spidrid negotiating a 3D terrain. Perhaps I should go for a photorealistic animation? How about the 'Crown of Thorns' (Coruna spinea) making its way over rocks? Or the 'Blue Jester' (Fossor azureus) walking on the forest floor? The 'Lesser Strandsprab' (Nepa aranea) would do well on a beach, but the 'Hairstar' (Coma confusa) would be difficult to depict, with its hair cover. By the way, all of these appear in paintings I am working on...