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| Butterfly Crabs | |||||||||||||
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| Topic Started: Jul 16 2008, 01:49 PM (2,324 Views) | |||||||||||||
| Livyatan | Jul 16 2008, 01:49 PM Post #1 | ||||||||||||
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The butterfly crabs are among the most successful animal groups on Tethys. They consist of several dozen orders of species from flatmoths to crabwhales. They occupy many niches including predators, scavengers and detritivores, filter-feeders (like whale sharks), and algae-eating browsers. Butterfly crabs range in size from a mere inch (flatmoths and scuttlelobsters) to nearly ninety feet in length (crabwhales). Even with such ecological diversity and immense evolutionary success, they all are quite similar in body plan having achieved a perfection similar to that of the crocodilians on Earth, being able to be great adapters while still maintaining the essence of a basic body plan. Anatomy ![]() Butterfly crabs and their relatives are basically similar to Terran arthropods. They have segmented bodies and jointed appendages as well as strong exoskeletons. The exoskeleton is leathery and quite flexible as opposed to how it appears. All butterfly crabs share the same basic external anatomy, the main differences being the length and shape of limbs, the shape of the thoracic segments, length of the pygidium, size of eyes, etc. One of the key differences between butterfly crabs and the arthropods of Earth is how the antennae evolved: on Tethys II, the antennae of butterfly crabs evolved from hypersensitive, elongated mouthparts. Overtime they lost their use in feeding, but became important sensory devices.
Edited by Livyatan, Jul 20 2008, 01:25 PM.
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| PousazPower | Jul 16 2008, 02:24 PM Post #2 | ||||||||||||
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Cladistic Kid
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Technically, a pygidium is a terminal body region with the anus/cloaca on the end, so in this case, the "pygidium" would be a telson, because there's no gut in it (or if there is, it doesn't terminate there). | ||||||||||||
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Was your nose discovered or invented? PousazPower on DeviantART | |||||||||||||
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| Livyatan | Jul 16 2008, 03:00 PM Post #3 | ||||||||||||
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Well technically its not Terran anatomy so the definition of the different parts may be different. |
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The grand Livyatan on deviantArt: link | |||||||||||||
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| PousazPower | Jul 16 2008, 04:01 PM Post #4 | ||||||||||||
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Cladistic Kid
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Are the mouthparts modified legs like in Terran arthropods, or did they evolve from something else? | ||||||||||||
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Was your nose discovered or invented? PousazPower on DeviantART | |||||||||||||
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| Livyatan | Jul 16 2008, 04:13 PM Post #5 | ||||||||||||
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No they did not. The mandibles actually evolved long before life became similar to arthropods. Many of the major classes in Tethys are descended from a group of small segmented worm-like creatures with tooth-like projections around their mouths. In eelworms, parrotworms, etc. these became their four mandibles (which actually function more like the beak of a bird). In butterfly crabs they became arthropod-like mouthparts. I'll have a cladogram for butterfly crabs pretty soon with some more insight into their ancestors. Quick question: the common ancestor of these major groups only has one set of eyes, so is it possible for creatures with two sets of eyes to evolve from one-eyed ancestors? Edited by Livyatan, Jul 16 2008, 04:15 PM.
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| Sliver Slave | Jul 16 2008, 04:38 PM Post #6 | ||||||||||||
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I'm going back to basics.
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Oh, you, teasing with that crabwhale picture. Also, I need a decent imperial to metric calculator. These "feet" and "inches" are confuzzling me. Edited by Sliver Slave, Jul 16 2008, 04:38 PM.
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Something is upsetting the ostriches. Spoiler: click to toggle | |||||||||||||
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| PousazPower | Jul 16 2008, 04:52 PM Post #7 | ||||||||||||
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Cladistic Kid
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Certainly! The eyes of spiders are actually individual facets of the ancestral chelicerate lateral eyes that have expanded to become something like giant ocelli, which, in some cases, are capable of forming images. So if the ancestral eyes were compound, then they could split into as many different eyes as there are ommatidia. Something else from the Holy Tome of Invertebrate Zoology: "The anterior lateral eyes, posterior medians, and posterior laterals are secondary eyes. These indirect eyes are thought to have derived from the lateral compound eyes of the ancestral chelicerate, although they no longer retain the faceted construction of typical compound eyes." This has also happened in vertebrates, namely the four-eyed fish (Anableps sp.) Although the eyes aren't totally separate, I'm assuming they could be completely bifurcated in the near future. |
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Was your nose discovered or invented? PousazPower on DeviantART | |||||||||||||
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| Cynovolans | Jul 16 2008, 05:52 PM Post #8 | ||||||||||||
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Servant to Empress Min
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I believe one foot is 30 cm, and 1 inch is 1.5 cm. BY the way, those are cool! Especially the waspcrab. Edited by Cynovolans, Jul 16 2008, 05:53 PM.
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I wish I could give the public a true picture of the queen as she appeared at her best, but this would be impossible, even had she permitted a photograph to be taken, for her charming play of expression while in conversation, the character and intellect which were then revealed, were only half seen when the face was in repose. -Lilias Underwood when speaking of Empress Myeongseong "I was born in the dark. I went out into the light, and your Majesty, it is my displeasure to inform you that I have returned to the dark. I envision a Seoul of towering buildings filled with Western establishments that will place herself back above the Japanese barbarians. Great things lie ahead for the Kingdom, great things. We must take action, your Majesty, without hesitation, to further modernize this still ancient kingdom."-Min Young-ik to Empress Myeongseong | |||||||||||||
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| Livyatan | Jul 16 2008, 06:14 PM Post #9 | ||||||||||||
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Just so you all know there are several more groups of butterfly crabs, including: sandsifters, algal crabs, turtlecrabs, etc. Algal crabs and turtlecrabs are unique among butterfly crabs by being the only herbivores. Sandsifters are a more basal group related to the immense crabwhales. A sister group to the butterfly crabs that I have yet to design will consist of zooplankton like creatures. The larvae of true butterfly crabs, sparrowworms, and tongueworms will also be members of the Tethyian zooplankton.
Edited by Livyatan, Jul 16 2008, 06:16 PM.
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| Saxophlutist | Jul 16 2008, 06:34 PM Post #10 | ||||||||||||
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Adult
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I like what you've done here. Despite the outward arthropod-like appearance, I would guess that these guys would be the "vertebrates" of your planet? |
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| Livyatan | Jul 16 2008, 06:39 PM Post #11 | ||||||||||||
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There are no "vertebrates" on Tethys. The closest things to vertebrates would be sparrowworms and relatives, although that lack an internal skeleton. Actually there internal anatomy is set up more like annelids, but that is a whole different group. Butterfly crabs, on the other hand, are actually as similar to arthropods as their outward appearance suggests. |
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| Saxophlutist | Jul 16 2008, 07:04 PM Post #12 | ||||||||||||
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Adult
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Well, what I meant by that ["vertebrates"] is, that they are the dominant macro-faunal organisms on your planet? In turn, making them effective vertebrate analogues. (Sorry for not phrasing it better ) Somewhat in the same way I refer to my "Sagitta" infraphylum as Europa's vertebrate analogues. (Though they are somewhat more like echinoderms, but only negligibly) Edited by Saxophlutist, Jul 16 2008, 07:07 PM.
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| Livyatan | Jul 16 2008, 07:14 PM Post #13 | ||||||||||||
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There isn't a single major faunal group that could be identified as the 'vertebrates'. All species are pretty much 'invertebrates'. |
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The grand Livyatan on deviantArt: link | |||||||||||||
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| Cynovolans | Jul 16 2008, 07:16 PM Post #14 | ||||||||||||
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Servant to Empress Min
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I wish these were real, I would like to keep some of them in an aquarium. | ||||||||||||
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I wish I could give the public a true picture of the queen as she appeared at her best, but this would be impossible, even had she permitted a photograph to be taken, for her charming play of expression while in conversation, the character and intellect which were then revealed, were only half seen when the face was in repose. -Lilias Underwood when speaking of Empress Myeongseong "I was born in the dark. I went out into the light, and your Majesty, it is my displeasure to inform you that I have returned to the dark. I envision a Seoul of towering buildings filled with Western establishments that will place herself back above the Japanese barbarians. Great things lie ahead for the Kingdom, great things. We must take action, your Majesty, without hesitation, to further modernize this still ancient kingdom."-Min Young-ik to Empress Myeongseong | |||||||||||||
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| Saxophlutist | Jul 16 2008, 07:23 PM Post #15 | ||||||||||||
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Adult
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That's actually very good! It means you are able to move away from terrestrial analogues.I mostly was able to do that, except some of my organisms seem to Cnideria-esque. |
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It means you are able to move away from terrestrial analogues.
9:42 AM Jul 11