At some 120 pages, The Book is steadily progressing, slow as ever, but getting there. I thought I would let you have a peek at a recent painting. The Book should show at least some of the myriad small animals that make up the bulk of Furahan animal biomass, and so I painted a few. But after that, the final series of paintings will probably show big hexapods only!
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| Click to enlarge; copyright Gert van Dijk |
What you see here is just a fragment of a painting, and it is even more limited in that it only shows the head and neck of the most important animal on the painting. I turned the layers containing the other parts of that animal to invisible, so there will be something left for The Book. That head belongs to a 'lice eater', an insect-sized animal of the type usually labelled as 'wadudu'. Wadudu are reminiscent of arthropods, but they have a mesoskeleton, not an exoskeleton. Admittedly, the difference in skeleton type is only obvious for the largest wadudu, the size of mice and sparrows.
Anyway, this 'lice eater' carries the scientific name of Ulla sanguisuga. It should not be difficult to work out where the inspiration of that name came from.
Its prey consists of 'plant lice'. That is not a clade, but a simple group designation for all the little animals that make a living by sucking plant sap. The plant is question belongs to a major plant clade called the 'poliochromes'; they have a photosynthetic pigment that absorbs light across most of the visual spectrum, explaining why these plants are generally dark grey.
To mimic the effect of macro photography, I first painted the entire scene as I would normally do, and then rearranged everything in layers that represent distance to the imaginary camera. I left only one layer in focus, and blurred to varying degrees. We now have depth of vision on an imaginary planet; you would think that photography a few centuries into the future would have done away with such blurring, but no, here we are...
A mesoskeleton? hmm, wonder how that'd work. Would they have muscles pushing on the inside as well as on the outside? Perhaps like the hydraulic muscles of Snaiad?
ReplyDeleteAlso the bugs look kinda like the kaiju "fleas" from Pacific Rim.
"The size of mice and sparrows" so the wadudu are similarly constrained in size like earth insects?
ReplyDeleteI, Anthony Docimo, offer this:
ReplyDeleteIts quite a good image you've made. Kudos!
IMHO, there will *always* be blurring in photos and paintings. Sometimes deliberate, sometimes not.
>Ulla
sounds familiar...the Norse goddess of skiing, yes?
(masculine form is Ullr, god of skiing, son of Sif)
$wampm0nster: yes, a mesoskeleton. No, it is not a hydraulic skeleton. I't an exoskeleton with a few modifications 9that I will keep to myself for the time being...). I did not think the giant monsters in Pacific Rim were appealing and did not see the film.
ReplyDeleteThe WingedScourge: I was more thinking about the mass of mice and sparrows, with the intention to give them the ability to become noticeably larger than Earth insects. Perhaps I should pick other examples.
Anthony: thanks! I agree that forming images with lenses must result in some blurring. But if a future light sensor would be much more sensitive then current ones, the aperture can be smaller with better depth of field. The logical end would be a pinhole camera. But blurring has its charms.
As for Ulla: no, that's not it.
Firstly, that's another good painting. Will different clades of wadudu have a varied number of limbs like arthropods do?
ReplyDeleteSecondly, a light-field camera can also produce a large depth of field without restricting the size of the aperture. Lytro attempted to produce a consumer model but it wasn't a commercial success. Coincidentally, it was only yesterday afternoon that I mentioned this on the speculative evolution forum as a possibility for organisms with many eyes.
Fascinating concepts in the design! I love how the wadudu are designed, it's interesting to see how different mini-organisms can fill insect niches in alien worlds without looking too much like earth insects, with Snaiad's Picotheres coming to mind. I do wonder if a vertebrate-esque creature with a cartilage skeleton could exist at such a size.
ReplyDeleteI'd also always been thinking how an alien ecosystem would fill "bug niches" that teem in sheer numbers and "megafauna niches" that vertebrates fill on earth. How exactly does that divide arise, especially since the arthropods did grow huge in the absence of vertebrate competitors? Would oxygen levels of the atmosphere be a deciding factor? Or perhaps even number of limbs? Why did the wadudu end up becoming the "bugs" of Furaha while the hexapods and rusps became the big creatures? Hmm.
(also, I can't help but note how the anthony posts always introduce with "I, Anthony", it's for some reason strangely adorable)
The creature's yellow head looks a fair bit like a surprised face emoji, would be an amusing little detail if Furaha scientists saw the resemblance and named it in reference to it.
ReplyDeleteAbbydon: yes, wadudu have various numbers of legs. Actually, the lice in this painting are larval forms with 6 legs as larvae but eight as adults.
ReplyDeleteI had read about that Lytro camera. I see you have found your way to the forum, as I suggested. I think you will feel right at home!
Sarah Kerrigan: thank you. There are some very small frogs around, but their numbers are very small. It does make you wonder why there aren't more. Of course, many larval fish and amphibians are small, so if that would be a good strategy, you would expect some of them to stay at that size, but they don't. The blame for arthropods not succeeding at large sizes is usually sought in a variety of answers, from exoskeletons getting impractical at large sizes to respiration systems that do not lend themselves well to scaling up. Mind you, there have been giant millipedes in times when oxygen was NOT high, so oxygen is at best only part of the answer. I should look the matter up, but doubt that are definitive answers to both questions.
t o m a t o: I agree about the surprised look. At first it had antennae, but it did not seem to need them. It would indeed be a nice reason to name the beastie, but it already has a scientific name: Ulla sanguisuga. So far, no-one has guessed where that came from yet...
A possible reason for the minimum size of vertebrates could be that an endoskeleton works better at larger sizes than an exoskeleton, especially on land. This suggests that vertebrate evolution favoured the "large animal" niche. Perhaps the resulting "design" has a minimum size, possibly due to a limit on the minimum number of cells and/or the minimum cell size?
ReplyDeleteThis is perhaps supported by the fact that the smallest chordate is not a vertebrate but a tunicate. Oikopleura dioica is apparently between 0.5 and 1.0 mm long.
If vertebrates had been the first to colonise land I wonder whether they would have evolved to fill the small niche before invertebrates filled it?
I who am Anthony who is pleased and honored by Sarah Kerrigan's compliment, do say...
ReplyDelete(I do that lately, because the page doesn't always say who I am, even when I use my Google Account; *shrug* these things happen)
usually, when vertabrates get teeny tiny, they start losing bones - and the loss isn't undone when any of their descendants get bigger again. (is isn't so much that there is a divide, as they have other problems such as dispersal - look at the tiny chameleons of Madagascar, for example, who can easily hitchhike on millipedes)
Mesoskeletons are found in starfish and sanddollars, aren't they?
How about coconut crabs? They're the largest terrestrial invertebrate alive today and they seem to do well on land at such an immense size despite having an exoskeleton. Certainly not as big as the largest vertebrates, but still quite enormous.
ReplyDeletedoes "Ulla" have any connection to the AYULF on the "swimming with membranes" page? (as yet unnamed life form...so Ulla is "unnamed little life form"?)
ReplyDelete-anthony
Abbydon: The lack of a large overlap in body size between invertebrates and vertebrates may be looked as two separate problems.
ReplyDeleteWhy aren't vertebrates small? But they can be! Larval fish and amphibians take enough food from their environment to grow, proving that they can thrive as small creatures. (In water, anyway; perhaps on land too.) This suggests that there is nothing in their basic Bauplan that argues against small size. In turn, if it is not a factor within vertebrates, then we may have to look for an external factor. Perhaps the 'small world' is already filled to capacity by very capable arthropods and other invertebrates?
Why aren't invertebrates large? Some are now, such as coconut crabs, and some were then, as Cambrian forms show. At the time, there were no vertebrates, so perhaps the lack of Cambrian-sized arthropods now argues that competition is part of the answer. But there were never any hippo-, elephant- or sauropod-sized invertebrates, so I think that part of the answer lies in factors within invertebrates. The usual suspects are respiration, moulting and exoskeletons.
Anthony: that's a good point towards 'allowing' small terrestrial vertebrates
Jonathan: I agree that they are large, but that is in comparison to other arthropods only. There is still a very significant size gap.
Anthony: nice try, but no cigar. Perhaps it is an age thing. I grew up with this. Very well, I will tell you: https://www.youtube.com/watch?v=NkXAmx33pj0
Maybe reproduction is a size issue for vertebrates? There's a species of tiny worm sized snake that can only lay one egg at a time that hatches into a baby already almost half the mother's size at birth. Compare to invertebrates that can spawn hundreds of young at once...
ReplyDeleteNasodromeus: that is an interesting point. Fish and frogs can in fact produce large numbers of eggs, but it does seem to be true that the individual vertebrate egg is a lot bigger than the usual invertebrate egg. But you could say that that is just an alternate approach: instead of many who start at a very small size, even fewer but at a larger size. But would it affect preferred adult size?
ReplyDeleteWith a reduced quantity of offspring produced plus a higher risk of predation, it's likely that micro-vertebrates simply can't keep their populations up the way insects and other vertebrates can?
ReplyDeleteI suppose one major constraint of vertebrates is just how viable their newborns are at tiny sizes, with smaller and less-developed offspring having lesser chances of survival. That said, there are marsupials, which are born in essentially an early embryonic stage but already able to survive despite their tiny size, and in one small possum species newborns have been reported to breathe through permeable skin due to their undeveloped lungs, so perhaps retaining extremely neotenic traits could be a step toward dealing with constraints for micro-vertebrates?
ReplyDeleteAs for insects, there is apparently one species of wasp that is smaller than a paramecium or amoeba, though the constraints of microscopic-scale arthropods may be another story entirely...
Would a mesoskeleton imply the presence of muscles both inside and outside the hard supporting skeletal structures? I can imagine such an arrangement giving rise to specialized carnivores that adapted to get at the inner meat most other carnivores can't access, using a combination of hyena-like bone-cracking jaws and a long, barbed, anteater-like tongue to pick out the meat inside of the bones. They'd likely be scavengers that follow weaker-jawed predators to make kills and then wait for them to clean up the outer meat before going in to deal with the inner meat the other predator can't get to...
ReplyDeleteA problem that small amphibians have is that they have such a large surface area to volume that they lose water through their porous skins and become desiccated. This is why they only live in humid environments. This doesn't apply to arthropods as their exoskeleton is good at retaining moisture.
ReplyDeleteSimilarly, mammals and birds cannot reach small sizes as they would lose heat too fast for the same reason. Obviously cold blooded creatures don't have this problem.
I'm not yet sure what would prevent reptiles or fish from becoming smaller, though I still suspect it is due to attempting to shrink a "design" that was originally optimised for larger animals.
one thing to do is define "small" :D
ReplyDelete(hummingbirds and bee-sized bats exist, after all)
Malagasy chameleons are itty-bitty.
another thing to do is speculate on why they'd bother to get smaller.....why do bats, hummingbirds, and chameleons do it? (or, for that matter, we know of fossil mammals whose entire skull can fit on the eraser of a #2 pencil?)
-Anthony Docimo.
assume that an exoskeletal animal the size of say, a cow, were to exist because reasons. what external factors (gravity, oxygen, muscular structure, number of limbs) would make it feasible
ReplyDeleteThe smallest hummingbird is a giant at 55 mm compared to the smallest frog at 8 mm. The smallest mammal is only a bit smaller than the hummingbird so I'm fairly sure that small warm blooded animals are unlikely.
ReplyDeleteHowever, while most small frogs lose the tadpole stage there is apparently a 2.6 mm predatory tadpole, so perhaps the minimum size limit in water is a bit lower as desiccation is no longer a problem. There don't appear to be any equally small fish though.
ypsigon: I do not yet understand why small vertebrates would have a higher risk of predation. Is that compared to equally-sized invertebrates?
ReplyDeleteTalking gorillas: your exceptions to the rule are well noted, but I still don't really understand why the rule seems to be the way it is...
dung beetle: the mesoseleton would indeed by on the outside, well, except for a skin, on some parts of an animal and on the inside, well, with tissue between it and the skin, so your predatory equipment would make sense. Now I've given it away: with a mesoskeleton, the skeleton is NOT the skin...
Abbydon: the heat loss problem is why I earlier reserved small vertebrate size to fish and amphibians. Their design may be optimised for larger size, but evolution is about evolving another optimum. What's keeping them?
Anthony: yes, there is an overlap, but don't you agree than most species of vertebrates and invertebrates are found outside the overlap, at opposite ends?
Worthless etc.
that is a subject worthy of a post or two, and i doubt that the essays would reach a strong conclusion. Still...
Abbydon: also all true, but it seems we are not really getting closer to explaining all aspects of the size gap. For me, the big unanswered problem is not so much the lack of big arthropoods, but the lack of small vertebrates.
>yes, there is an overlap, but don't you agree than most species of vertebrates and invertebrates are found outside the overlap, at opposite ends?
ReplyDeleteI agree...but there are other clades that also overlap with the categories of "big inverts" and "small verts".....such as the largest protists and algaes. I'm not sure if the answer would be more likely to appear if we included the algaes, or less likely to appear.
sorry, misread your question.
As far as I know, even the largest of inverts are tiny when they hatch - so there is probably a limit as to how big they can get to, considering each brood would be getting picked off by predators all the while. (coconut crabs live on islands, so thats at least a little protection)
...contrasted with how the smaller verts take less time to reach adult sizes, which aren't terribly different from the size of the infants; so they may have far smaller broods than larger verts and equal-sized inverts, but it takes less time to reach brood-producing sizes.
-Anthony Docimo.
I think that there are two related but slightly different size comparisons here. The first concerns vertebrates vs. arthropods on Earth. The second concerns exoskeletons vs. endoskeletons on another planet.
ReplyDeleteThere seem to be several possible reasons that terrestrial arthropods have a maximum size. Some of these reasons are linked to their use of an exoskeleton (i.e. moulting, weight, joints, etc). However, other limitations are not (e.g. respiration). Similarly, vertebrates appear to have a certain minimum size and while the exact cause of that isn't yet clear it does not appear to be directly related to the endoskeleton. It may be because the structure of vertebrate organs assumes a certain size and/or number of cells and therefore they cannot be miniaturised in a series of incremental evolutionary steps.
However, on an alien planet the question can be simplified to, "Could small organisms have an endoskeleton?" I suspect the answer is yes but that an exoskeleton is more likely. Exoskeletons initially act as protective armour whereas an endoskeleton doesn't provide this benefit. The advantage of an endoskeleton (i.e. weight saving) is only achieved in larger organisms and so endoskeletal life will naturally become larger. Small endoskeletal life may only be viable if it can successfully compete with small exoskeletal life. If a minifish-like organism became the first terrestrial animal then perhaps small "vertebrates" could fill Earth insect niches though?
Abbydon: I agree that the questions run the risk of being bundled. The size limits of vertebrates vs arthropods need not be due to one of their most conspicuous differences, i.e. the type of skeleton. It is well possible that an endoskeleton does not limit small size, but that other factors do. It is also possible that an exoskeleton does constrain large size, possibly along with other factors.
ReplyDeleteBy the way, if you change arthropods to invertebrates, the landscape changes again. Just consider big cephalopods....
Anyway, the next post will be a review of a book about creature design.
Adding hydroskeletons to the mix seemed like it might complicate things further. It is interesting that the giant gippsland earthworm can apparently reach up to 3 m in length though. Assuming the desiccation problem is addressed I wonder what the maximum size limit for land based hydroskeleton is. Could a thick skin become an exoskeleton so that you would end up with a large exoskeletal snake?
ReplyDeleteI wonder if there are any other skeleton options? Is a pneumatic-skeleton using gas possible in a similar way to how land crabs stay mobile after moulting?
How many eyes does Ulla sanguisuga have and how are they arranged around its head? As a predator I'd imagine that they'd face forward, but I wonder how well the "forward eyes = predator, side eyes = prey" concept works when said creature has more than two eyes to work with...
ReplyDeleteif spiders are any clue/indication, its not a matter/question of "do they face forwards?"...its "how many face forwards?"
ReplyDelete-anthony
if all vertebrates were to suddenly die out, would any invertebrate clade have a shot at becoming the next dominant megafauna on earth given their anatomy and how they might evolve to be bigger? definitely not the squids regardless of what FiW might say
ReplyDeleteApparently the eye positioning thing is most important in jumping spiders which have four eyes that face forward, two that face sideways and two that face backward. I wonder if Ulla sanguisuga has a similar division of labor among its multiple eyes?
ReplyDeleteAbbydon: I wonder if such large worms have a trick to compartmentalise their body, or else they need much muscle action all over their bodies to get something done in a small portion. I doubt anything pneumatic would work: gases compress so much, in contrast to fluids.
ReplyDeleteBubbles: five: one large median unpaired one, and four small ones, placed more laterally; two are placed higher than the median eye, two lower.
Anthony: the fields of vision of the small eyes overlap partially with the field of the large eyes. This is the standard wadudu pattern, but in some the media eye is nearly gone, and in others it is prominent.
Anatotyrannus: that's too large a question to ask here...
splatypus: well, the median eye has detailed vision, and the lateral ones widen the visual field and provide depth information.
I agree that a pneumatic skeleton seems unlikely. I thought the combined pneumatic-hydrostatic skeleton was interesting though as it was discovered in terrestrial crabs and was used to support the body after moulting. Due to the terrestrial lifestyle there may not be sufficient water to produce a pure hydrostatic skeleton. This seems to be a possible issue for large exoskeletal organisms.
ReplyDeleteIn worms, I believe that the hydrostatic skeleton is a series of discrete segments. I've just become sidetracked reading about worm size and apparently, unlike endo or exoskeletal organisms, worms scale isometrically. Effectively, large worms are almost identical to small worms. The reason for the maximum size limit is not known but could be due to various other factors.
Cool to see another example of a mesoskelaton, my speculative planet has one of the major clades of land life use a mesoskelaton of selenium sulfate helices to support their weight.
ReplyDeleteAbbydon: interesting! I admit that I never considered a pneumatic 'skeleton' before. Should that be called an aeroskeleton in view of the 'hydroskeleton'?
ReplyDeleteSpooktober: I just tried to find your world, but there are so many links to 'spooktober' that I could not find it. Do you have a link?
What I did find is that the term 'mesoskeleton' is also used in the context of the Alien films. I did not know that, and just cobbled 'meso' and 'skeleton' together, thinking that 'middle' is a nive term if you are neither inside nor outside. But I now think that, if a skeleton is partially on the inside and partially on the outside, then it is not so much in the middle as it is both outside and inside. I think I will change the term to 'amphiskeleton' to reflect that ('amphi'='both') and to steer away from the use in the Alien context.
I have not yet created any online sites for my project although i intend to in the future. I did not know that the alien films called it a mesoskelaton. It is interesting to see your take on a mesoskelaton, in my case i meant it more as a secondarily mesodermal structure with muscles on the outside, inside and within most of the structure. It would take a while to explain the development of the structure but i call it a mesoskelaton because of it housing the mesoderm aswell as seperatly housing the internal organs. However, an amphiskelaton describes the mid point in its development quite well as it would have been like that as the structure was in the proscess of evolving.
DeleteSpooktober: either name should do nicely. For Furaha, I'll go with 'amphiskeleton' though.
ReplyDeleteCool, i think it is a good word, good look with the book
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