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Natural Science Forum / Biology / Biology / July 2008Please help identify this swimming creature
Hi. I came back from a short vacation only to find this interesting creature swimming in my pool... http://home.jetbroadband.com/~jhoerner/files/pool_worm.mov http://home.jetbroadband.com/~jhoerner/files/pool_worm1.jpg http://home.jetbroadband.com/~jhoerner/files/pool_worm2.jpg The chlorine was pretty low, but not zero. It kind of looks like worm, but is not slimy nor squishy; it's more snake-like. I am uncertain if it needs to surface to get air, but it does stay submerged for long periods. Its body is cylindrical and about 1 mm thick. It has no clear head nor tail, but one end is blunt, and the other pointed. I figure the blunt end is the head. If it is removed from the water, it often stiffens up like a slightly bent twig and will balance on my finger like a miniature boomerang . If the water cools down, it coils up. What is this creature, is it a human parasite, and if not should I bother to dump it into a local stream? Chlorine is on the way up, so I'm not putting it back in :-). Your help is appreciated. I know nukes, not biology. Thanks, Jim Hoerner -- Hold the door for the stranger behind you. When the driver in the adjacent lane signals to get over, slow down. Smile and say "hi" to the folks you pass on the sidewalk. Give blood. Volunteer. I finally found it. It's a horsehair worm. Strange lifecycle. Jim -- Hold the door for the stranger behind you. When the driver in the adjacent lane signals to get over, slow down. Smile and say "hi" to the folks you pass on the sidewalk. Give blood. Volunteer. >I finally found it. It's a horsehair worm. Strange lifecycle. Cool. I thought that might be it but was confused by the blunt head end. I've occasionally seen them in my garden after heavy rains but didn't look at them carefully enough to observe that. They do have a strange way of moving in air. These harmless creatures were once the subject of a folk belief that they were spontaneously generated by horsehairs in water and were mentioned as evidence in 18th century arguments on that topic. In those early days of modern science, people did experiments like soaking horsehairs, and letting meat rot in screened containers to see whether or not maggots really were spontaneously generated. This was a major controversy at the time, and an early example of scientific method, as opposed to citing Aristotle or reasoning from first principles or religious texts. >Hold the door for the stranger behind you. When the driver in the >adjacent lane signals to get over, slow down. Smile and say "hi" to >the folks you pass on the sidewalk. Give blood. Volunteer. Do as you would be done by. The more people do it, the more it works. I like to compliment supermarket cashiers on their memory of prices and skill at packing groceries when relevant. Everybody needs to be appreciated, especially people at work in miserable jobs. Of course, up here in Canada, civility is a national trait. On Jun 26, 5:41 pm, jim_hoer...@hotmail.com wrote: > If it is removed from the water, it often stiffens up like a slightly > bent twig and will balance on my finger like a miniature boomerang . Does it show extinction of that behavior if you do it many times? If so, maybe you can teach it tricks. Then again, how do you reward a worm? Robert >On Jun 26, 5:41 pm, jim_hoer...@hotmail.com wrote: > [quoted text clipped - 4 lines] >so, maybe you can teach it tricks. Then again, how do you reward a >worm? Just like anything else. You give it a little treat. > >Does it show extinction of that behavior if you do it many times? If > >so, maybe you can teach it tricks. Then again, how do you reward a > >worm? > > Just like anything else. You give it a little treat. But what's a little treat for a tiny thing like a worm? It has to be something it exhausts quickly. >> >Does it show extinction of that behavior if you do it many times? If >> >so, maybe you can teach it tricks. Then again, how do you reward a [quoted text clipped - 4 lines] >But what's a little treat for a tiny thing like a worm? It has to be >something it exhausts quickly. It was a joke. Just do the slightest research on Nematomorphs (horsehair worms) and you find that the adult stages do not eat at all. The larvae are parasitic on insects. So the only thing you can do with an adult like the specimen shown is to identify its sex and try to entice it with a member of the opposite sex. That is, if it has not already mated and is now near death. > >> >Does it show extinction of that behavior if you do it many times? If > >> >so, maybe you can teach it tricks. Then again, how do you reward a [quoted text clipped - 8 lines] > (horsehair worms) and you find that the adult stages do not eat at > all. But I didn't think "treat" had to mean "food". > The larvae are parasitic on insects. So the only thing you can > do with an adult like the specimen shown is to identify its sex and > try to entice it with a member of the opposite sex. That is, if it > has not already mated and is now near death. Yet it has what seems to be behavior, unless I'm mistaking reflexes for what appears to be goal-directed action. Stiffening and balancing would seem to be some attempt to avoid peril, but it may be just a series of reflexes. Then again, what Eric Kandel sometimes labeled "learning" in Aplysia seemed to me to be just reinforcement of a reflex. I think what he did in teasing out the changes at the molecular level were great, and MAY reflect similar changes that take place in actual learning, but calling it learning I always considered a bit bombastic. Robert >> >> >Does it show extinction of that behavior if you do it many times? If >> >> >so, maybe you can teach it tricks. Then again, how do you reward a [quoted text clipped - 26 lines] >MAY reflect similar changes that take place in actual learning, but >calling it learning I always considered a bit bombastic. I followed Kandel's work for some 40 years and he always thought rather highly of the "complex behavior" of his slimy things, something usually looked at with some amusement by those of us interested in "real" animals like crustacea that have "real" behavior. Still, he did enormously important work with it, working out mechanisms for rather complex long-term changes including a form of associative learning. Kandel's Nobel Prize was well justified, on a par with Pavlov and Sherrington, also Nobelists for mere "reflexology". Incidentally, reflexes ARE real behavior and come in a tremendous range of complexity. Depending on what you mean by "goal directed", reflexes can easily qualify. What you observed probably was some combination of locomotory and escape behavior. There is very little work done on nematomorph nervous systems except some basic anatomy -- they do have a brain, dorsal and ventral nerve cords, and a peripheral nervous system, much like nematodes. But nematodes, especially the species Caenorhabditis elegans, are well studies in terms of behavior with specific genetic mutants that affect behavior analyzed at the level of single nerve cells. Many animals at this level of organization (flatworms, roundworms) are capable of classical learning. The horsehair worms are all parasitic and have very specialized life cycles but are still capable of rather complex activity. Probably the most famous is the ability of the horsehair worm larvae to influence the behavior of its insect host, driving it "crazy" to commit suicide by drowning, a behavior that allows the developing adult horsehair worm to emerge in its aquatic habitat. > Incidentally, reflexes ARE real behavior and come in a tremendous > range of complexity. Depending on what you mean by "goal directed", > reflexes can easily qualify. Then we need a word for behaviors that are not completely accounted for by reflex. > What you observed probably was some > combination of locomotory and escape behavior. How could an escape behavior not be locomotory? Robert >> Incidentally, reflexes ARE real behavior and come in a tremendous >> range of complexity. Depending on what you mean by "goal directed", >> reflexes can easily qualify. > >Then we need a word for behaviors that are not completely accounted >for by reflex. If you know something about animal behavior, especially invertebrate behavior, then you know that even rather complex stimuli (sign stimulus) can evoke extremely complex patterns of behavior (fixed action pattern). See http://en.wikipedia.org/wiki/Fixed_action_pattern >> What you observed probably was some >> combination of locomotory and escape behavior. > >How could an escape behavior not be locomotory? The term "locomotory" applies to any sort of locomotion; swimming, walking, flying, slithering, etc. Of course I meant "ordinary" locomotion in this context. "Escape behavior" is a different very specific pattern of behavior, again often a fixed action pattern in invertebrates. A lot of this behavior, including locomotion, may be completely genetically programmed although often subject to environmental modification or modulation. The distinction you are probably looking for is the difference between innate, genetically controlled, instinctive behavior and learned behavior even though there are many things that are combinations. |
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