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Valhallah; An alien planet-that-isnt-a-planet
Topic Started: May 9 2009, 11:01 AM (7,636 Views)
El Squibbonator
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Curse you and your sudden but inevitable betrayal!
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I should have said that. The species in these descriptions aren't necessarily going to be ones I mention when I cover families. That's because these documentaries are meant to give a broader view of life on Valhalla (or, coming soon, in the Neozoic.)
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El Squibbonator
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At long last, an update! This one needs a little background. Due to a combination of Valhalla's low temperature and its small size, it lacks any body of water as large as Earth's oceans. Its water life is dominated by the Ichthyomorphs, aquatic "vertebrates" that arrived at a vertebrate-style bodyplan quite independently from quintapods and other true vertebrates. The largest of these are the Water-rakers (family Megistichtyhidae), which are Valhalla's resident filter-feeders (the presence of such creatures being a recurring theme on various worlds). Ranging from 25 to 50 feet long, they somewhat resemble basking sharks in that they use their gills to strain plankton from the water.

Notable Water-raker species include
Imperial Water-raker (Megistichthys gigas)
Silver Water-raker (Megistichthys argyra)
Pied Water-raker (Megistichthys melanoleuca)
Polar Water-raker (Megistichthys borealis)
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El Squibbonator
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Valhalla now has a poll attached. Since it's been trickling to a halt, I've decided to let you help me decide what form the project should take in the future. The poll will be up for a month.
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El Squibbonator
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Sorry it's been so quiet here. I hope to get this topic up and running again very soon, and I have plenty of new material. This time, it's more tubugnaths. The tubugnaths, if you remember, are Valhalla's equivalents of insects and crustaceans, and their species number in the millions. Like their earth counterparts, they have managed to conquer not only the land and water, but the air as well. Flying tubugnaths have wings that evolved from their aquatic ancestors' gills. One notable family of these is the Rattleflies (family Hoplopennidae), whose rigid beetle-like wings make a distinct clicking sound in flight. Like all tubugnaths, they have a complex life cycle with many larval stages.

Notable rattlefly species include:
Horned Rattlefly (Ceratodens horridus)
Parasol-tree-boring Rattlefly (Xylophilis sylvestris)
Four-eyed Rattlefly (Tetraopthalmus viridium)
Shovelhead Rattlefly (Ammocephalus apteryx)

PS: You might remember a clade of proto-"vertebrates" I called the Ventrognaths that I originally planned as the arthropod-analogues. They've been bobunked.

P.P.S. Here's a picture of a Golden Mantipede, another type of Tubugnath.
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Attachments: Mantipede_bak.jpg (27.81 KB)
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Empyreon
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Are you plausible?

What's the scale of this clade? If they're arthropod analogues, I don't imagine they're very large.

And I'm assuming you've included the image of the golden mantipede because it's closely related and thus a close example of what rattleflies look like. Is that a correct assumption?
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El Squibbonator
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Tubugnaths generally don't get much bigger than a human hand and most are much smaller than that. Mantipedes, like the one in my picture, are among the largest of them. I put in the Mantipede picture mainly because I don't have any other groups of terrestrial tubugnaths illustrated right now. Rattleflies actually look something like a cross between a beetle and a crab, with large pincers as forelimbs. I should have a picture up soon.
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colddigger
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Joke's over! Love, Parasky
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Do they use lungs to breath? I apologize if you previously mentioned it.
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Empyreon
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Are you plausible?

El Squibbonator
 
Tubugnaths generally don't get much bigger than a human hand and most are much smaller than that. Mantipedes, like the one in my picture, are among the largest of them.

It seems to me that the legs, on the mantipede at least, are needlessly thick and poorly positioned to deal with the creature's center of gravity.
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El Squibbonator
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What would be a better size/position?
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Empyreon
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Are you plausible?

I don't have the information or formulas gathered at the moment to speak with any exactitude, but my instinct says that those legs could be half as thick as that, or at least 75% as thick. Also, try and gauge the position of the feet so that they're under the center of gravity of the body. It looks like the mantipede has a theropodal design, which means that it could balance itself with a counterweight (longer and/or more massive tail) or the legs need to extend forward so the feet are under the center of the body's gravity.

I also wonder about the physiology, like colddigger. What's their skeletal structure like? What prompts their theropodal design?
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El Squibbonator
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All excellent questions. This would be a good place to discuss tubugnath anatomy, which I regret not doing earlier. Most tubugnaths walk on all fours, but the Mantipedes belong to a group that radically altered their internal structure early on in their evolutionary history and are now bipedal. Tubugnaths, as I have mentioned before, are considered "invertebrates" on Valhalla, they lack the skeletal structures found in land "vertebrates" and ichthyomorphs.
Tubugnaths have exoskeletons, but theirs are different from those of Earth arthropods in that they are flexible and leathery rather than stiff and jointed. Like insects and crustaceans, tubugnaths go through a series of larval stages before their exoskeletons fully form. In some cases these larvae are bipedal "hoppers", and the Mantipedes are neotenic descendants of these.
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Russwallac
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"Ta-da!"
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Aren't larvae, in general, less active than adults to divert more energy for rapid growth? Why would larvae be high-energy hoppers?
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El Squibbonator
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I have a question that I really should have asked long ago: what do you think Valhalla's atmosphere should be like? Should we assume it would resemble Earth's because of the presence of complex carbon-based life, or could it be something totally different? All I've really decided on after all this time is that it's much thinner than Earth's atmosphere.
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El Squibbonator
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(Looks at calendar) Wow. Has it really been THAT long since I added a new family to Valhalla? Today's feature's going to be a new family of frish (the common name for ichthyomorphs), called the Aquameleons (family Cryptochloridae). These are essentially the Valhallan equivalent of scorpionfish or anglerfish, since they use a head-shaped appendage on their dorsal fins to attract victims, who are then stabbed by the syringe-like mouthparts and sucked dry. They can also change color much like a chameleon or octopus in order to camouflage themselves.

Notable species of Aquameleon include
Dragon Aquameleon (Hydrodraco atrox)
Cave Aquameleon (Crytochlora spelea)
Double-headed Aquameleon (Amphicephalus decepitcus)
Torrent Aquameleon (Scyllichthys magnificens)
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