Cephalocaudal perception?
399919
Typically a neonates growth is generally referred to in terms of cephalocaudal or proximodistal patterns . \nThe cephalocaudal pattern is where the greatest development takes place at the top of the body, i.e. the head, and physical development moves gradually downwards: e.g. neck, shoulders, trunk, etc. \nThe proximodistal pattern of development is where growth starts at the centre of the body and moves towards the extremities. An example of such a pattern is the early development of muscular control of the trunk and arms relative to the hands and fingers. \n\nMore info here ...\nhttp://www.hon.ch/Dossier/MotherChild/postnatal/development.html
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The basic answer is that symmetry is efficient from the point of view of growth of a multicellular creature.  The same DNA plan to construct the left side can also construct the right side.\n\nThe bigger question is why are we symmetrical from left to right, but *asymmetrical* from front to back?  (Dawkins covers this.)\n\nThe answer goes all the way back to an early stage in evolution where, basically, worms  were the dominant body plan.  \n\nThere are advantages to creating a separate opening for eating and excreting ... namely, it reduces the chance that the worm will reingest something it has just excreted.  So one end becomes the "front" end, for eating, and the other end the "rear" end for excreting.  As sense organs are far more useful for eating, they would tend to develop near the front end.  This in turn would cause nervous-system organs for processing sense information to be near the senses (the brain also goes to the front).  And all appendages that develop for locomotion, would develop to propel the organism forwards (towards the "front"), which is why tails (originally used for swimming) develop in the "rear" end, fins and legs are structured to push backwards.  And so on.\n\nHowever, while there is an advantage for front-rear asymmetry, there is no significant advantage to left-right asymmetry.  We don't find food more often on the right than on the left.  Predators don't attack more often from the right than from the left.  So it is advantageous to have sense organs arranged to look both left and right (two eyes two ears), and limbs arranged to move us both left and right (left limbs, right limbs).   So left-right symmetry has stayed.\n\nSo basically, we are bilaterally symmetrical, because almost all animals (except for things like starfish), had a common ancestor with a 'wormlike' body plan.\n.
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Plesse go to this website \n\nhttp://www.umm.edu/spinecenter/education/anatomy_and_function_of_the_spine.html
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I used to love this theory as well, but apparently it's not too popular in the scientific community.  I'll try to find some links.\n\nhttp://en.wikipedia.org/wiki/Aquatic_ape_theory#Objections_to_Aquatic_Ape_Hypothesis
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Your most advanced animals have what is called bilateral symmetry.  This simply means they have two sides to their body.  The right and the left.  They also have what is called cephalization where most of the organisms sense organs are located in the area of the head.  It is a body plan that seems to work in the scheme of evolution.  It helps the animal adapt to a new environment since the head is the firs body part to enter it.
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Author:      Lou Harnisch\n"This falls under the study to social contact (grooming) for species that have, particularly mammals that have highly social groupings.  Being ticklish would certainly draw more attention to that individual from other members of the group.  Creates positive interactions that strength bonds.  It would be interesting if one could find a structural (receptor) or physiological (brain wave pattern) that would be strongly correlated with the "ticklish state" and see if these kinds of things are found only in highly social mammalian species."\nAlso\n"Because tickling involves the sensitivity of our skin, we do start out with natural differences in ticklishness, much as we have differences in our hearing or eyesight.\n\nBut tickling is different because it's social; it's not like sight or smell, says Robert R. Provine, a professor of psychology and neuroscience at the University of Maryland who studies the tickling response and is the author of the forthcoming book ``Quest for Laughter.''\n\n``The tickling story is far more interesting than anyone has anticipated,'' says Provine. ``If you think the social component is not important, try tickling a stranger.''\n\nAlthough tickling, like reflexes, involves neurological mechanisms, it is far more than an involuntary response. You can give yourself a knee-jerk reflex, but you can't tickle yourself, says Provine. Tickling is a form of communication used between friends, family and lovers, and one that Provine thinks may play a key role in the evolution of our social and sexual behavior.\n\nChimps tickle each other during play. Children are playfully tickled by their parents and other children of both sexes. Above the age of puberty, though, tickling usually is a form of flirtation, he says.\n\nSo why are some people more sensitive than others? Provine theorizes that the differences lie largely in who is doing the tickling. You may be highly sensitive to being held down and tickled by an older brother, for instance, because it's somewhat aversive. But a lover's tickling may not annoy you at all.\n\nAcquiring sensitivity to ticklish stimuli might have been highly useful in our evolutionary past, says Provine. It would have warned us if a poisonous scorpion was crawling along our neck. And the parts of our bodies that are highly vulnerable to injury, like our feet, chest and armpits, are among the most ticklish."
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I don't know about all the changes over the last 30 years, but I do know a few more recent ones.  With back they are allowing flip turns now.  With breast, they allow one dolphin kick during your pull out, you're head can now be completely submerged during the stroke, and when you do your turn you are now allowed to have your hands on different plains as long as they touch at the same time.
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THis was by Caitlin T. Mueller\nunder the direction of\nDr. Michael Levin\nForsyth Institute\nResearch Science Institute\nAugust 1, 2002\n________________________________________\nVarious training methods have been used in learning experiments, the most popular being\nclassical conditioning, which exposes a test subject repeatedly to a Conditioning Stimulus,\nor CS, followed immediately by an Unconditioned Stimulus, or UCS. For example, in this\nstudy the CS is a change in overhead illumination, and the UCS is a weak electric shock. The\nUCS induces a consistent reaction in the subject called the Conditioned Response, or CR, in\nthis case, a longitudinal body contraction. Eventually, after many trials, the subject begins\nto anticipate the UCS by sensing the CS. A subject has “learned” when it has expressed a\nCR following a CS, but before the onset of a UCS. [9]\nPast research has shown that this method is effective in training planaria. [2][10][11] After\na planarian has been successfully trained, it can cut transversely into anterior and posterior\nsegments, both of which regenerate into separate individuals. It has been shown that both\nsegments retain the memory of their predecessor. Additionally, it has been observed that\nplanaria regenerated from both anterior and posterior regions retain the same amount of\nknowledge, suggesting that cephalization is not necessary for memory retention.[12]\nThis is a noteworthy finding because it refutes most of the commonly accepted theories\n1\n________________________________________\nPage 4\nheld today asserting that memory storage is a purely neurological mechanism [1]. The\npurpose of this particular study is to first reaffirm the assertion that planaria are able to\nlearn, and then to investigate the nature of the planarian memory mechanism. Inquiries\ninto this mechanism may hold vast implications for understanding learning and memory on\na broader level.\n2 Materials and Methods\n2.1 Basic Planaria Care\nThree species of planaria were studied in this experiment: Dugesia dorotocephala, Dugesia\njaponica, and Phagocata gracilis. The D. dorotocephala and the P. gracilis were obtained\nfrom Ward’s Biological Supply. All D. japonica were derived from one planarian transferred\nfrom Japan, and were therefore genetically identical. The planaria cultures were stored in\nrectangular plastic containers measuring 22 cm × 22 cm × 7 cm filled with Poland Spring\nwater and incubated at 18\n◦\nC. The culture was fed organic chicken liver twice a week. Excess\nmeat was removed with pipettes after three hours, and the water was exchanged twice\nto remove residual waste and debris. Planaria were observed regularly under a dissecting\nmicroscope to monitor health. Unhealthy worms were removed from the general culture and\ntreated with various antibiotic treatments.
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I think all vertebrates use the same system we do.\n\nbugs have sensory hairs at all their joints. Especially the joints to head and to abdomen tend to be most important for gravity/balance perception (most mass attached). \nIn flying insects the ocelli (three single lens eyes on the top of their head) are thought to help with flight stabilization. Also flying insects have halteres to help with flight stabilization\n\nJellyfish, mussels and other marine invertebrates have statoliths/statocysts. Statoliths are made of a particular dense material and their displacement during acceleration/deceleration can be measured. \n\nI don't think bacteria care, but then they are not animals
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They are actually increasing their range of vision by tilting their eyes toward the ground. Birds supposedly are extrasensory feelers, so they probably "sense" worms.
684621
attitude, looks and brain.
102657
Most likely for depth perception.
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Depth perception is the ability to see objects in 3-D.\nHumans have depth perception because of the location of their eyes on the front of their face. If our eyes were on the sides of our head (i.e. mice) we would not have depth perception. Having eyes located on the front of the head is a characteristic of predators who must judge distances between themselves and their prey. Animals who are commonly prey often have their eyes on the sides of their head to give them a greater angle of view, but less depth perception.\nDepth perception is achieved when the brain processes the slightly different pictures from each eye and combines them to form the 3-D image we see.\nDepth perception allows us to visualize distances between objects. It is what allows us to tell if something is near or far. If you did not have depth perception, you would have difficulty estimating distances.\nPeople who lose the sight of one eye often have difficulties with depth perception. If you covered one eye and tried to play catch with a friend, you would find that it would probably be difficult to judge exactly where the ball was. Over a period of time, you would learn to adjust for this, but your depth perception would continue to be hindered.\nHope that was helpful.
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You are clearly referring to the Class Cephalopoda (squids, octopi, etc.).  It is in the Phylum Mollusca.  Most molluscs, however, have moderate to poor eyesight relative to arthropods and cephalopods (snails and clams are molluscs) so saying the Phylum Mollusca is the correct choice is a bit off.
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http://serendip.brynmawr.edu/bb/neuro/neuro98/202s98-paper1/Boyce.html\n\nToo much information to copy out, but my Aunt found this website handy
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Yes, I live in a suburban area close to the coast in Buenos Aires, Argentina. Some years ago, excavations were made in order to install sewers (believe it or not, we were not connected to the public sewer system then!) and the workers dug up large fragments of fossil whales. I only have a fragment that could be part of a humerus, but more complete whale skeletons often appear when people around here construct large swimming pools. \nThese bones are not of much paleontological interest, though. They're much too "new" and do not correspond to any uncommon or interesting species.
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Externally they have spines, tube feet, pedicellaria, all of which are attached to the calcium carbonate test. The muscles attached to all these parts allow movement of these parts. At the ventral mouth reveals their "aristotle's lantern" aka their fancy mouth-mouthparts designed much like garbage disposal blades.  The 5 white teeth set up like a grinding-beak can eat away at the kelp bed.  Inside they have some organs, mostly reproductive organs that hold their gametes between spawnings-breedings.  They also have a digestive system with an anus. They have a water vascular system inside which circulates water for a hydraulic pump, NOT blood!