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| Sif; a planet of golden plants and land reefs | |
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| Topic Started: May 24 2009, 10:51 PM (1,450 Views) | |
| Vultur-10 | May 24 2009, 10:51 PM Post #1 |
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This is a planet I'm working on. It is called Sif, after the Norse goddess known for her golden hair, because of the predominantly golden color of its plant life. Basic data: Sif is a little smaller than Earth (surface area 411,750,000 sq km, diameter 11,450 km) and of very slightly lower density. Its mass is about 4.2 x 10^24 kilograms. It orbits about 0.93 AU away from a sun of somewhat lower luminosity than ours. It is the second planet in its solar system, between sun-grazing Muspellheim (0.03 Earth masses, 0.09 AU) and the gas-giant Jotunheim (1.3 Jupiter masses, 3.2 AU). Sif's axial tilt is less than Earth's (15 degrees), giving it a larger temperate zone and smaller tropical, arctic, and antarctic regions. Sif has a single large moon, Mani (2% of Sif's mass). Another moon, no more than one-billionth of Sif's mass, may have existed at some point; some studies have suggested that the impactor that made the massive crater in the northern regions of Ullr may have been a moon that spiraled inward. Geography: Sif's surface is a little more than 80% covered by water, somewhat more than Earth. There are two continents – one, Ullr, lying entirely in the southern hemisphere, and the other and smaller one, Thrud, surrounding the north pole. Ullr is somewhat larger than Eurasia; Thrud, slightly smaller than Antarctica. These two continental masses occupy 17% of the planet, and various islands between 2 and 3%. The largest island group is the Lorithi cluster, named after its largest island, which lies north of Ullr. Its northernmost small islands lie north of the equator. Ullr's north is dominated by the immense Loki crater. This crater's interior, lying partially in the tropics and having a very low elevation, is Sif's warmest area (summer temps around 32 C, winter temps around 25 C). It contains a small sea, which is not contiguous with Sif's planetary ocean. It is slightly saltier than the ocean, but not so much as to impede a rich variety of life. Loki crater, around 350,000 square kilometers, is Sif's richest ecoregion. It includes some of almost all floral groups except the antarctic disks and those exclusive to Thrud, but the golden springtrees, knife palms, and shiningchains are especially notable. The dominant plant community is a mixed forest, though there are many savannahs. Northcentral and eastern Ullr, where the crescent-shaped continent bends east, are the zone of land-reefs. This area is fairly low and warm, but still quite cool by Terran standards (summer temps around 25 C, winter temps around -5 C). The reef-building plants are the dominant visible feature of this area, and their reefs are the dominant ecosystem. The southern body of Ullr, as the continent bends west again, is a plain rising toward low hills at the southern end. This is a quite cold land in winter (summer around 18 C, winter around -15 C) and accumulates deep snow. The dominant plant community is a prairie of golden whipgrasses and gladius palms. The very southwestern tip of Ullr leads into a peninsula made of jagged, high mountains, the result of ongoing collision between Ullr's tectonic plate and that of the antarctic islands. This Skadi Peninsula extends past Sif's antarctic circle. Its northern areas are cold but livable (summer around 5 C, winter around -35 C); its southern areas are a bitter cold that only a few forms of very hardy life can endure (summer around -10 C, winter around -65 C). Most of the Skadi Peninsula is glaciated, especially the southern end, but ice-free valleys exist: these are occupied by a very sparse community dominated by the antarctic disk plants. Thrud's north and west is a series of plateaus around the north pole. These are heavily glaciated (up to 5000 m thick in some areas) and the plateaus' rock has been pressed down by the weight of the ice; otherwise, they would be quite high. This area is at least as cold as Antarctica's coldest regions (summer around -35 C, winter around -80 C). Central Thrud is a low, chilly region of tundras and taigas dominated by several plant clades unique to Thrud: the fractal-branched trees and the grassferns. Summer is around 18C, winter around -10. Southeastern Thrud is another set of plateaus. These are cold (summer around 12 C, winter around -15) and have some glaciated regions. This area has the only green plants known on Sif. Sif Life: Sif life is based on TNA (threose nucleic acid), not DNA. The major groups of Sif life are the seabed microorganisms (Akarya), xenoamoebas (Bikarya), other microorganisms (Monokarya), and complex lifeforms (Sinumembrana) - themselves divided between plants (Xenoflora) - the rare green plants may or may not be members of Xenoflora; the data is still unclear - photosynthetic 'animals' (Florofauna), microscopic worms (Nanovermes), and purely-heterotrophic animals (Eufauna). It is not yet known whether the 'giant worms' are a group of their own between Nanovermes and Eufauna, or are actually animals - research into this group is very difficult, since they are rare, sink quickly when dead, and are sufficiently deadly to be practically impossible to study while alive. Some genetic data exists, but it shows such a distant relation to any other known group that it is of little help. --- Sorry if that post was a bit long; I'll hopefully start posting species tomorrow. Edited by Vultur-10, Jun 1 2009, 12:23 AM.
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| ATEK Azul | May 25 2009, 03:10 PM Post #2 |
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Transhuman
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this planet sounds amazing and i would love to hear more about the life forms keep up the good work this is awsome. |
| I am dyslexic, please ignore the typo's! | |
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| Terrence of Chance | May 25 2009, 04:06 PM Post #3 |
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Infant
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This is one of those things that would benefit greatly from a map of some sort. I know that there are generators of sorts around the web... |
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| Empyreon | May 26 2009, 01:13 PM Post #4 |
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Are you plausible?
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Sounds like an interesting project! I can't wait to see more! |
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Take a look at my exobiology subforum of the planet Nereus! COM Contributions food for thought
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| Vultur-10 | May 26 2009, 05:56 PM Post #5 |
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Bunnywing (Florofauna: Pseudolimaces: Leporala pilosa) Size: length 15-25 cm, fin span 10-16 cm, mass 100g - 600g Range: waters off the eastern coast of Ullr - continental shelf and continental slope This strange marine creature resembles a furry, golden slug with two enormous flaps, like the ears of a rabbit, extending from its head. These are actually large fins, which are used in swimming via underwater 'flight' like a penguin's. Being photosynthetic, bunnywings are generally found in the sunny upper layers of the ocean; but, since they can obtain nutrition from food as well, they occasionally turn up in surprisingly deep waters. Of all the 'pseudo-slugs' , the bunnywing is the deepest diver, recorded at up to 520 meters down. (Deep-water surveys on Sif are ludicrously incomplete, however, due both to the relatively small population on the planet, the fact that even the land areas are poorly explored, and the dangers of the giant worms.) The golden 'hairs' covering its body are actually the photosynthetic organs, similar to leaves: each hair is rich in auroplasts (the equivalent of chloroplasts for the golden plants and photosynthetic animals of Sif). Besides photosynthesis, a bunnywing eats photosynthetic microbes, plant matter both living and detritus, and the occasional smaller animal. Bunnywing reproduction is odd by Terran standards, though the pattern is not unusual on Sif: bunnywings reproduce sexually, but they are unisexual (not merely hermaphroditic). That is, the two haploid gametes that fuse to create a diploid organism are identical (except, of course, for the differences in the genes they carry.) Bunnywings expel gametes into the surrounding water whenever they detect a significant quantity of a pheromone produced by all adult bunnywings. The gametes combine; the larval bunnywing is entirely photosynthetic until it grows to a sufficient complexity and size to begin eating microscopic plankton. Walking-weed (Florofauna: Ambulatoria: Xenodionaea ambulans) Size: up to 3-4m tall and 6-7m across, mass 500 to 1800 kg Range: Loki Crater - savannahs and open forests This photosynthetic 'animal' is one of the most plantlike in appearance of the group. It is a mass of thick, leaf-covered stems tightly twining around a central sac, with other stems branching off to form a thick fringe dotted with eyes, scent receptors, and jaws. It moves on eight stumpy legs. It lives in any habitat within its range open enough for its large body - it requires great warmth, though, and thus is found only in Loki Crater. Its 'vine' stems and leaves appear green, a rather rare color on Sif - this organism has chlorophyll-containing chloroplasts as well as the golden auroplasts. A walking-weed eats anything organic that does not move out of its way - plants, detritus, carrion, sleeping animals. Even the top layer of soil is skimmed for usable organic matter. A walking-weed is nearly impossible to poison, with an incredible resistance to most toxins -- but even so, considering its omnivory, poisoning is still one of the more common causes of death. (This is also because a walking-weed is very difficult to kill in any other way: its tough vines protect the sac containing vital organs, and many of those are redundant anyway. A large predator could kill one, but due to their diet, they are quite distasteful.) |
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| ATEK Azul | May 26 2009, 06:16 PM Post #6 |
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Transhuman
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those are very interesting organisms i like the slug with bunny ears the best though the walking weed is cool too. |
| I am dyslexic, please ignore the typo's! | |
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| Vultur-10 | May 26 2009, 10:52 PM Post #7 |
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Hamlin's Thorned Death (Florofauna: Ambulatoria: Mortispina horribilis) Size: body 50-70 cm long, tail 30-50 cm long; mass 15-50 kg Range: Loki Crater Named by early explorers of Loki Crater for a biologist killed by the creature, Hamlin's thorned death was considered to be one of Sif's most deadly predators -- until its larger relatives were discovered. This thorned death rather resembles a Terran mountain lion crossed with an alligator, but it has six legs and its entire body is covered by flat, thorn-like projections (its photosynthetic "leaves", tough enough to survive a serious struggle with prey undamaged), and its belly (containing the relatively fragile tubes and stingers it uses to feed) can be covered by an armor plate. If these tendrils (used to inject digestive acids and enzymes into the prey and ingest the soupy remains) are damaged anyway, they regenerate quickly. A Hamlin's thorned death kills with wickedly hooked claws on its front two legs (which are usually held clear of the ground). Once the prey is wounded, the thorned death follows, slashing at it, until it falls dead. It then sits on the prey, injecting digestive fluids and removing all useful nutrients and calorie-rich meat. Hamlin's thorned death is faster than any of the other photosynthetic animals, capable of achieving 35 miles per hour in a full sprint, and 28-30 miles an hour in a long-continued run. Thorned deaths are dioecious: males and females are separate individuals. Thorned deaths use external fertilization; the female lays her eggs in a dead, uneaten, prey, and the male fertilizes them. Then both parents spray the corpse with a fluid toxic to most scavengers (and even somewhat toxic to adult thorned deaths) but harmless to juvenile thorned deaths, which possess the enzyme needed to break it down. Giant Plowhead (Florofauna: Ambulatoria: Aratrocephalus megas) Size: 7-16 meters long; 2-4.5 meters tall; mass 4,000-60,000 kg Range: Loki Crater The plowhead, though rare, is one of the main reasons Loki Crater has savannahs and other treeless areas, despite the extremely rapid growth of its vegetation. This enormous herbivore, as large as a Terran whale (though not even close to Sif's worldwhales), eats everything -- animals, plants, soil. Even soft rock may be scraped to add minerals to the plowhead's diet. Enormous paths are carved through the land by a plowhead; but its droppings provide both new seeds and nutrients to the land, and new plants spring up in its wake. The creature's rear half resembles a Terran sauropod dinosaur, except that it is golden and covered in long photosynthesizing 'hairs'; its front half is a massive head, armed with the plow-like beak (12-15% of the creature's total length) that gives it its name. Plowheads are dioecious and externally fertilizing; they reproduce rarely, and live very long lives - the exact length is uncertain, but in the 110 years humans have observed Loki Crater, several individual plowheads have changed little, except to grow somewhat larger. Some project total lifespans of around 500 years; others suggest even longer. Despite their size, plowheads are not entirely immune to predators, but successful attacks are exceptionally rare. The only predator ever known to succeed is the giant thorned death. Giant Xenonematode (Nanovermes: Detritivora: Pseudovermes gigas) Size: 1.5-4 mm long; mass 2-25 micrograms Range: Loki Crater While it seems odd to call a creature which never reaches half a centimeter 'giant', the Giant Xenonematode is by far the largest organism in its entire kingdom, Nanovermes (the xenonematodes): only two other known species are visible to the unaided eye, and both barely reach 1 millimeter in the largest individuals. Like all other xenonematodes, it lives mainly on detritus. It will often prey on microscopic lifeforms, however. It is found in the shallow swamps and marshes of Loki Crater. Giant Xenonematodes, like most xenonematodes, reproduce asexually by budding: the tip of the tail end develops a bud, which develops into a tiny individual (identical in form to the adult) and drops off. The Giant Xenonematode has over 8,000 cells, more than any other xenonematode is known to have. (Many have been barely studied beyond the simple description and name, however; even the megafauna of Sif is still sparsely known, and these attract far more researchers.) [/i] Edited by Vultur-10, May 26 2009, 10:53 PM.
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| ATEK Azul | May 29 2009, 07:04 PM Post #8 |
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Transhuman
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these sound amazing i can't wait for more. |
| I am dyslexic, please ignore the typo's! | |
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| Vultur-10 | May 30 2009, 04:05 PM Post #9 |
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Barnacleye (Florofauna: Molluscoidea: Oculabalanus horridus) Size: 5-10cm long (shell); 20-50cm long (including tentacles) Range: seas around the Lorithi islands and north coast of Ullr This creature resembles a huge barnacle, with very long, thin tentacles. At the center of the ring formed by the bases of these tentacles is a mouth, surrounded by a single, huge, ring-shaped eye. Four of its eight tentacles are coated in thin branching fronds, used to photosynthesize. These are drawn up out of the way when the barnacleye seizes prey. The other four are unbranched and used to capture prey. The hard segments of its shell are covered in a thin, photosynthetic mantle. Barnacleyes are found only in the very upper layers of the ocean, attached either to rocks, driftwood, or (in deeper water) the tops of seafloor trees. They reproduce during stormy weather, as the water is churned by storms: they release unisexual gametes, like the bunnywings. |
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| Deleted User | May 30 2009, 11:50 PM Post #10 |
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Sounds well thought out. Except, wouldn't golden plants loose a lot of potential light energy since they're reflective? Can you explain TNA a bit more? |
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| Vultur-10 | May 31 2009, 11:50 AM Post #11 |
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They don't actually reflect light in a metallic manner, like the metal gold; they're just gold in color, ranging between the color of ripe wheat and a pumpkin. The dominant pigments are xanthophyll and carotene, with smaller amounts of chlorophyll, mostly chlorophyll-b, in some plants. As for TNA, it's a nucleic acid using threose as the sugar instead of ribose (as in RNA) or deoxyribose (in DNA). It has only been made in labs, and not found in nature, so far. But it's been suggested that very early life may have used it on Earth, since threose is a simpler sugar; and I wanted something other than DNA or RNA for an alien planet. Edited by Vultur-10, May 31 2009, 11:51 AM.
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| Vultur-10 | May 31 2009, 12:11 PM Post #12 |
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Heimdall Giant Worm/Butcher Beast (?: Gigahelminthes: Gigahelminthus carnifex) Size: (only complete specimen, juvenile) 20.31 m long, 8226 kilograms; (estimated adult size) 32-36 m long, 40-45 metric tons Range: Poorly known. The only complete specimen is from the northeast coast of Ullr; evidence has been found along both coasts of Ullr and south of a small island near Thrud. This variety of giant worm was, for a long time, known only from marks found on parts of animals it had preyed upon. From the long slashes and deep cuts found in these animal parts, it became known as the "Butcher Beast". Eventually, shed teeth, up to 40 centimeters long long and very sharp, were found in a few carcasses. Even so, the variety of animal the "Butcher Beast" belonged to could not be determined. It was widely believed that it was one of the giant worms occasionally spotted at a distance, and which were thought by many to be part of the reason many deep-sea exploratory vehicles vanished, but this was unconfirmed. Finally, a dead giant worm washed up on Ullr's northeast coast, not far from the Heimdall Colony. Inspection showed that the huge teeth in its mouth were identical to the shed teeth of the "Butcher Beast". A closer study revealed something frightening -- this immense creature, ten times as long as a man's height, was not even full-grown! Its larger teeth were about 25 centimeters in length, not the 40 found in various carcasses. The Heimdall giant worm has three jaws, which are studded with long teeth. They close with immense force, enough to shear away any body part caught in the mouth. Calculations show that it would be quite capable of slicing steel, though it might lose many teeth in the process. Giant worm teeth, however, are readily replaceable. The teeth of the Heimdall giant worm are distinguished from those of other giant worms by a length:width at base ratio around 3:1 and 7-10 serrations per side. The diet of the Heimdall giant worm seems to include almost anything which is small enough to eat - and for a creature of this size, very few things are too big to eat. Its reproduction is completely unknown, and it has not been studied alive, for obvious reasons. Besides shed teeth and infant teeth found in the stomachs of large predators, four specimens are known. One, the only complete specimen, is the Heimdall individual. Two of the others were small individuals (the larger had teeth up to 19 centimeters long) collected via explosives at long distance; while this method provides reasonable safety for the researchers, it leaves specimens sadly incomplete. The fourth specimen was a very small individual, apparently an infant, with 4-centimeter teeth, found in the stomach of a bladdershark; it probably would have been around 3.25 meters long when complete, but it was quite digested. Despite this poor record, with four specimens and over 250 known teeth, it is the best-known giant worm (though some little is known about the behavior of the Abyssal giant worm). Edited by Vultur-10, May 31 2009, 11:05 PM.
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| SIngemeister | May 31 2009, 03:52 PM Post #13 |
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Hive Tyrant of the Essee Swarm
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Sounds like a match for my Mawworms. |
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My Deviantart RRRAAAAAARRRRGGGGHHH!!!!! | |
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| Vultur-10 | Jun 1 2009, 12:10 AM Post #14 |
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... and remember, this is just one species. (And, BTW, not the biggest ... not by a long shot.) What thread are the Mawworms in? They sound cool. Bladdershark (Florofauna: Nefastobufones: Nefastobufo mordax) Size: 1-14 m long; 0.9-16 m wide; 0.2-10 m high; 35-40,000 kilograms Range: Occasionally present in open oceans between 30 N and 40 S, common around the Lorithi Islands The bladdershark is a strange creature even by the standards of Sif. Its head has a great resemblance to that of an Earthly toad, except that it has four eyes and sharp, dagger-like teeth. Its body is mostly air-filled sacs; the head, digestive tract, heart, glandular sac (containing most of the vital glands), and the two large winglike fins occupy less than 20% of the bladdershark's total volume. (The value is about 18% in a newly adult individual, with a volume of around 0.2 cubic meters and a mass of around 35 kg; in the very largest recorded specimens, approaching 2,000 cubic meters, the value can be as low as 2%.) The air sacs are double-walled; the outer wall is full of photosynthesizing auroplasts, and between the two walls is a thin layer of fluid used to carry the photosynthetic products to the rest of the body. The air sacs are not just a resource-saving way to provide more photosynthetic area, however; they are also buoyant, keeping the bladdershark floating high in the water. They are not filled only with air, however, but also with the bladdershark's gaseous wastes, such as methane. The bladdershark can fill its sacs from the atmosphere or release air from its sacs into the water; it releases air when it wishes to travel faster than the current or against it, sinking deep enough to give its large fins purchase. Normally, it floats just deep enough to keep its eyes and mouth underwater; this leaves almost two-thirds of its volume above water, allowing the bladdershark to look smaller and less threatening as well as breaking up its form. In addition to photosynthesis, a bladdershark will eat any creature that passes nearby. The bladdershark gets a good deal of its nutrients, though relatively little energy, this way; this, in addition to its hugely expanded photosynthetic area, allows it to grow larger than most photosynthesis-dependent lifeforms. (The walking-weed is the second largest photosynthesis-dependent lifeform on Sif, and even it gets only about 30% of its calories from photosynthesis, vs. the bladdershark's 85%. Any Florofauna larger than the walking-weed use photosynthesis only as a minor supplement - the giant plowhead gets about 5% of its calories from photosynthesis, and this amount can only be achieved by its massive ingestion of minerals- and some have lost the ability altogether.) Bladdersharks reproduce by releasing unisexual gametes, like bunnywings. The embryos grow very rapidly, at first by photosynthesis alone, then by capturing one-celled prey. From the time they are visible to a human eye (around 0.1 mm in diameter) to about 1kg, they live something like Earth's carnivorous plants: mainly by photosynthesis, with prey as only a supplement used for certain nutrients. During this time, they also float like plankton, and their fins have not yet grown. After that period, they become more predatory. Unusually, they become sexually mature at only a tiny fraction of their final size, which is why the range of adult sizes above is so wide. From the period of sexual maturity to about 3 meters long, they continue to grow quickly (a bladdershark reaches sexual maturity in a year, and ~3 meters in about three years). After this, their growth drops off dramatically. They continue to grow, but at a much slower rate, which is itself slightly slowing. A bladdershark which is newly adult will appear nearly flat, very wide but low in the water; as they grow larger and add more air sacs, they become stacked on top of each other. The only limit on a bladdershark's size seems to be that at which the sacs become so deeply stacked that the bladdershark has more body to support than its photosynthetic area can feed, even with prey as a supplement. Bladdersharks are very long-lived. The largest recorded (12.3m long, 15.98m wide, 9.67m high, 39,914 kg) is estimated to be about 340 years old. Abyssal Giant Worm (?: Gigahelminthes: Umbrivermes abyssalis) Size: (juvenile specimen) 0.7m long, 0.6kg; (incomplete specimen) 3.9m long, 232kg, reconstructed to be 6.3m long and 412 kg; (estimated adult size) 6-10 m long, 375-1750 kilograms Range: Poorly known. The two specimens were found: in a deepdiver stomach 180 miles off the north coast of Ullr, 60 miles south of New Wales in the Lorithi islands; and 110 miles off the coast of Ullr near Heimdall. This variety of giant worm is known only from 16 lone teeth and two specimens: one very juvenile and somewhat digested, the other adult but incomplete (due to the violence of the capture process). However, the teeth alone are clearly diagnostic. They have a length:width at base ratio of around 8:1 and are not serrated, both unique among giant worms. This tooth data, along with what genetic material could be extracted from the specimen, places the abyssal giant worm as the sister taxon of, and quite distantly related to, all other giant worms (the "true" giant worms, Eugigahelminthes). It is clearly a much more primitive form, probably a relic of a group which preceded the true giant worms and was mostly eliminated by competition with those more powerful predators. Like all giant worms, its body takes the form of a segmented tube, somewhere between triangular and round in cross-section. The abyssal giant worm's jaws are barely differentiated, simply three lobes of a single contracting mouth. Its teeth are very narrow, and thus much weaker than the Heimdall giant worm's, suggesting that it feeds on soft organisms. The abyssal giant worm is the only giant worm which has been observed alive successfully; one adult and one juvenile were observed hunting, and an adult was observed giving birth. The rear segment of its body was highly engorged, and infants were being expelled. Each infant was an almost threadlike worm, estimated between 10 and 15 centimeters long. When the remotely operated vehicle approached to closely inspect the infants, the parent attacked the vehicle, destroying its cameras and control system. It is also the only giant worm of which an adult specimen has been captured in recognizable form (although incomplete); this is due to its much lesser size and power and greater sluggishness. With more dangerous giant worms, the approved defense procedure using grenades and flechette guns is violent enough to leave little but mush behind. Edited by Vultur-10, Jun 1 2009, 01:23 AM.
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| Vultur-10 | Jun 1 2009, 12:51 AM Post #15 |
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More thoughts: I edited the introductory post to downsize Loki crater by about eight times - from 280,000 sq km to 35,000. The earlier size was far too big, since Chicxulub crater is about 180km in diameter - a circle with that diameter is about 25400 sq km. I can live with it being slightly bigger than Chicxulub - it needs to be big enough to form a distinct ecoregion and support large animals - but not *that* big; it can't be that far in the past, and I don't want it to have wiped out all complex life! (Frankly, I'm not sure if a little over 30,000 sq km of land area - three separate 'seas', two about the size of the Dead Sea and the larger one about the size of the Great Salt Lake, fill almost 5000 sq km of the area - is enough to support critters as big as my Giant Plowhead. I generally don't mind huge animals shoved into small 'lost worlds', but this case might be a bit extreme even for me...) So far I haven't posted any creature above 70 metric tons, but much bigger ones are coming. How do I justify bigger animals on Sif than any on Earth? Well, first, animals get bigger on Earth than are often realized. Blue whales can reach 200 tons, and Amphicoelias fragillimus, a sadly little-known sauropod, may have reached 100-120 tons and 60 meters in length! Secondly, plants can get much bigger than animals, and many of the bigger Sif creatures are partially photosynthetic. Thirdly, size is usually an advantage: larger animals need less food per kilogram, and on a cold planet like Sif, the increase in thermoregulation efficiency would be very important. Mass extinctions tend to wipe out big things preferentially, but Sif has had fewer mass extinctions (only 3, and the most recent was 85 million years ago - the Loki crater impact - rather than 65). Finally, life evolves faster on Sif (polyploidy and aneuploidy is more often survivable, and polyploids and aneuploids are more often fertile), so that 20-million-year difference is the equivalent of more like a tripling of the available time. Finally, why is Loki Crater still visible after 85 million years? Well, unlike Chicxulub, it hit fully on land and in a geologically inactive area; Sif is less geologically active, in general, than Earth; and it largely is eroded almost away, but the biota inside is very robust to outside invasion, but dependent on warm, wet conditions - which that ecosystem helps maintain. Essentially, the Loki crater ecosystem has become self-perpetuating, no longer really needing geographical barriers to maintain its integrity. |
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9:31 AM Jul 11