07:30 31-12-2011

anthony

Mr. Black - there used to be a biped hexapod on the furaha page...its image was replaced by the marblebill/shuffler.

18:17 27-12-2011

William Stephens

SN, earlier this year you said 'Barlowe tried animals without eyes (Darwin IV in Expedition), and I thought that that was a mistake, particularly if you do have bioluminescence.' I understand that eyeless creatures would not be able to communicate in the visible spectrum without sight (perhaps ultraviolet or infrared biolights, but then those on the paintings wouldn't be visible and Barlowe's creatures would need extra sensors) but could sightless animals evolve anyway? Could you possible do post on your blog on this subject?

15:38 27-12-2011

Evan Black

What leads you to believe that the middle pair is the most powerful, Jan?

Also, the examples of the hexapod carnivores are clearly adapted for quadrupedal movement. The same could be argued for the marblebill. I don't see any examples of bipedal hexapods, but that's not necessarily evidence against the idea.

05:55 27-12-2011

Anthony

the faster they go, the more dangerous any falling becomes...this is true no matter what the basal number of legs is.

12:35 26-12-2011

Jan

Thanks for the new post! Btw, it seems that the most powerful pair of legs of the furahan animals is the middle one. Is it plausible? Also, would not the hexapods switch to quadrupedalism or bipedalism for higher speed?

21:04 18-12-2011

Zerraspace

I do not intend to cut into this conversation, Sigmund Nastrazzurro, but I would ask for your professional opinion regarding a creature of mine. Some time ago (early May, I believe) I mentioned a Zainterian invertebrate called the morningstar, a vastly muscular organism that walked using tentacles that also served to pry open shelled prey from the inside. Thanks to your “Walking with Tentacle” discussion, I realized this would be futile, and asked for your view of the dilemma. You gave three suggestions – using bones, turgor, or Eponan pushing muscle, but I did not want to give up use of tentacles or take what I felt was an Eponan idea and not my own (although I did implement turgor in another Zainterian phylum). The issue has continued to puzzle me for the past few months, but I may have since found a solution. Instead of being purely muscular, morningstar tentacles would contain several rings of rigid bone-like mass, unattached to each other so as to allow tentacle-like flexibility and extendibility. When pressed against the ground, however, the tentacle can only compress to a limited extent before the rings are stacked on top of each other, providing what may be equivalent to a simple supporting leg (terrestrial variants will eventually adapt this into a stronger true jointed leg, but for the first amphibious and aquatic representatives this should do just fine). As for opening shelled prey, they would simply force the tips of their tentacles in (probably laced with several hooks or claws for better grip) rather than the whole tentacle, and use this grip to pull open the shell from the outside. For further force, muscles in different tentacles would attach to one another through additional muscles, the constriction of which would attempt to straighten them and provide more leverage. Once the gap is sufficiently enlarged, small mouth-lining tentacles plunge in, using their hook endings to sever flesh from armor and pull the meat out.

On another note, do you plan to create any predatory rusps? I realize you do not wish to divulge too much information about Furahan creatures so that there may still be some wonders for the book, but my brother entertains the notion of rusps ambushing their prey. He feels that they have enormous potential (particularly given their several legs and potent stingers), and has badgered me about it for the past week.

11:51 18-12-2011

SN

Sorry I have not been able to join in the conversation - too many other things going on...

As for the respiratory system, most points have been made already. Jan's list is extensive. Personally, I do not agree with the need for large openings: it is easy to move air quickly, so it can pass through a small slit or opening while entering the body. After that there is a need to catch particles of dust etc. before they reach the alveoli or whichever thin, moist and easily damaged structure does the actual gas exchange. It probably pays to move incoming air through convoluted passages to catch such particles. I do agree that using the same opening to let air in and out is bad design, as it means part of the work of moving air is useless as some of it merely goes back and forth (see 'dead space' in google). Furahan hexapods do not have air inlets on their heads, but at the front of the body. The exhalation aperture is at the end of the body. And all that was designed decades before Avatar's animals had the same design. Have a look at the Sawjaw. It it's case, the apertures are large as the animal breathes in water.

Jan: having two of everything is indeed not necessarily the best solution. I think I remember a paper about difficulties in localising the origin of sounds using just two ears. I will see whether I can track it.

07:49 16-12-2011

Jan

I have another problem interesting for speculative biologists - hearing sense and sound localization. Some animals like owls are dependent on the precise localization of sound source, but it seems to be much difficult task than visual localization. To localize sound both in horizontal and vertical plane by the use of interaural time difference or interaural intensity difference, the owl needs asymmetrical ears. http://en.wikipedia.org/wiki/Sound_localization Other animals use some other cues, like moving their ears or head, shape of their external ears, and so on. Insects are even more interesting than vertebrates, because they developed hearing more than one times http://what-when-how.com/insects/hearing-insects/
For example Ormia ochracea use mechanicaly connected tympanic membranes, which gives it superior ability to localize sound http://nelson.beckman.illinois.edu/courses/neuroethol/models/fly_hearing/fly_hearing.html
Maybe two pairs of similar ears on each side of head would provide the same ability to find the direction and distance of sound source as our pair of eyes does, at least in the horizontal plane (two triads may be necessary for the localization in both horizontal and vertical plane).
As it is usual with my human solutions to the biological problems, it may be overkill to use arrays of such ears for sound localization, but at least it would be somewhat alien.

There are even other possible solutions, but I do not know if they are possible for an animal http://en.wikipedia.org/wiki/Acoustic_source_localization#Particle_velocity_or_intensity_vector

09:32 14-12-2011

Jan

Warming could be done by other means, filtering and staving off infection is easier in bird-like lungs than in lungs with alveoli. I am trying to imagine some realy extreme type of adaptation to either low oxygen level or high metabolic rate (size also matter) and avoid the cummulation of functions for the head as in vertebrates (simply because I do not like it). There are other problems, though. How to smell, how to protect the openings against water, dirt, predators, and so on. The method of compression and extension the airsacks would be also important. With spine on the ventral side there would be much more space for them, but it may also makes the animal more vulnerable to falling object, burdens or predators. All of these problem could be solved, but to imagine something really realistic is not an easy task

16:51 13-12-2011

Evan Black

I agree that the respiration system should be more extensive than a narrow tube passing from one end to the other. Such a narrow, borderline-tracheal system would work okay for creatures the size of an insect, but for anything larger it needs a broader exchange surface; stretches of reticulated tubes coursing through the body like intestines or even actual spongy lung-like organs to do the bulk of the gas exchange. I agree that some system of air sacks would be helpful in the system as well, allowing air to be collected, perhaps even stored for later use, and to act as a bellows to maintain a constant air pressure, much as in birds.

In Point 3, Jan, you mentioned that there is not enough reasons to have a respiratory opening on the head. As I understand it, that is actually a method of warming the air as it enters the body, something you included in Point 2. Also, wouldn't having a large opening be counterproductive to attempts at filtering air or even staving off infection?

I also agree that the ideal respiratory system would be rather swift, to allow for a more efficient exchange of gases, especially if the exchange surfaces are so small as in the traffe diagram. Multiple hearts would ease the burden of higher blood pressures, so that each single heart isn't overtaxed. If the creature is particularly large (and from the diagram I assume the traffe to be anywhere from the size of a dog to that of a cow) this is especially true.

09:58 13-12-2011

Jan

The new post on blog bring me to another question, if the repsiratory openings aren´t on head, where they should be? If marshwallow have the openings on the ventral side, he would drown.

03:59 12-12-2011

Drás Researcher

Jan,
What if the surface area of the tubes were increased by adding tiny "alveoli" that run along the length of the tubes? This would provide more access to the oxygen and more access for "blood" to get oxygen.

19:56 07-12-2011

Jan

Just to add clarification, according to my opinion the Drás´respiration mechanism would not work, because there are not enough surface for exchanging gases and pushing the gas by waves of narrowing of the tube instead of simple pumping would be too complicated.

The best respiration mechanism would be probaly some variation on bird´s system but without its flaws. It is strange that the respiration system of the terrestrial organisms is probably more flawed than other systems even according to our limited undestanding of posssible alternatives. The optimal design would probably include following features:
1) two or more airsacks - the immobile lungs could use space more efficiently
2) separate openings for exhalation and inhalation - the air taken would be 100 percent fresh, there could be different specialization of the openings for warming and filtering the air and extraction of water.
3) openings should be large - there is not enough reasons to have them on the head.
4) the flow of the air should be unidirectional and constant (it demands at least two airsacks)
5) flow of the blood should be counter-current to air flow (I do not know why birds use cross current flow)
6) the erythrocytes would have greater oxygen carrying capacity and less energy spending without nucleus (free floating pigment of unknown composition could be even better).
7) the circulation of blood should be fast. I have proposed more constant (to some extent) flow of the blood by having two hearts working together.

Did I miss something or is it more complicated than I think?

01:19 07-12-2011

Spugpow

More walking with tentacles for your viewing pleasure : http://blogs.scientificamerican.com/video-of-the-week/2011/11/30/octopus-walks-on-land/

09:39 04-12-2011

Jan

Drás Researcher: This is roughly how apmhibians breathe http://en.wikipedia.org/wiki/Buccal_pumping

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