17 results found.
... Science Frontiers ONLINE No. 36: Nov-Dec 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Four 'clever' adaptations According to theory, many butterflies have wing patterns that evolved in response to predation. Some wing patterns blend into the background, making the butterfly hard to spot; other wings have prominent eyespots that are supposed to deter predators or trick them into striking at the wings instead of the soft, vulnerable body. But some tropi cal butterflies have a double problem; their predators change from dry to wet season. One butterfly, Orsotriena medus, masters this situation by changing wing patterns with the season. In the dry season, it is dark brown and inconspicuous; in the wet season, it switches to black wings with ostentatious eyespots and white bands. (Anonymous; "Cryptic Butterflies," New Scientist, 20, September 13, 1984.) The Asiatic freshwater clam has spread rapidly across North America since its accidental introduction about 50 years ago. In addition to its natural dispersal via its more mobile larvae, the young adult clams have a surprising method of hitchhiking rides on the water currents. Through their siphons they deploy long mucous threads. Water currents pull on these threads just as air currents catch the silken threads of migrating spiders. Given a water current of 10-20 cm/sec, the small clams manufacture and deploy their threads, and off they go downstream. (Prezant, Robert S., and Chalermwat, Kashane; "Flotation of the Bivalve Corbicula Fluminea as a Means of ...
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... Science Frontiers ONLINE No. 20: Mar-Apr 1982 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Heads or tails?Fake-head butterflies often escape predators that make passes at their cleverly designed tails, which as the figure shows, look awfully like butterfly heads, with eye spot, fake antennas, etc. Further, the converging stripes direct attention to the false head. The result is that this type of butterfly may lose its tail but save its real head. This effective stripe pattern has evolved (? ) independently at least six times in the Neotropics. (Robbins, Robert K.; "The 'False Head' Hypothesis: Predation and Wing Pattern Variation of Lycaenid Butterflies," American Naturalist, 118:770, 1981.) Comment. One wonders why all butterflies haven't evolved this neat ploy? From Science Frontiers #20, MAR-APR 1982 . 1982-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 71: Sep-Oct 1990 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Nature Communicates In Mysterious Ways Most of us will recall that the wings of butterflies and moths sometimes display eyespots, which, according to current thinking, are designed to startle potential predators. Perhaps so, but butterfly and moth wings can convey a wide range of "signals." K.B . Sandved, a nature photographer, has also found remarkable renditions of all the letters in the English alphabet (one at a time, of course) on the wings of these insects. In fact, he has accomplished this several times over using different species. He has found all the Arabic numerals, too, as well as ampersands, question marks -- you name it! Although Greek pi and capital omega have turned up, butterflies and maths are clearly trying to impress people who utilize the Roman alphabet. After all, it is difficult enough to evolve an ampersand; generating Chinese characters would strain credulity too much. (Amato, Ivan; "Insect Inscriptions," Science News, 137: 376, 1990.) Comments. Incidentally, of what survival value are these wing symbols? Obviously, the butterflies and moths have not got their act completely together as yet. Words and phrases will come soon, we are certain. Look at the eggplants for example. They have specialized in Arabic. It has recently been reported in British newspapers and on BBC Radio 4 that when the Kassam family sliced up an eggplant, ...
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... Science Frontiers ONLINE No. 116: Mar-Apr 1998 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Monarch Compasses Field experiments down the years suggest that migrating birds use a variety of strategies to chart their courses with high precision. The geomagnetic field, the sun, the stars, prominent landmarks, and even odors help guide them across the continents and open seas. But birds are considered highly evolved animals so their sophisticated navigational techniques are not especially surprising. Monarch butterflies, however, are mere insects, with tiny brains (navigation-data processors) and not much in the way of the environment sensors and internal clocks required for long-distance migration. Yet, some of these colorful insects manage to flutter up to 4,000 kilometers from the eastern U.S . and Canada to their wintering grounds in Mexico. How do they do this? S.M . Perez et al have now shown that monarch butterflies are equipped with a sun compass; that is, they chart their courses by noting the sun's changing azimuth. This feat requires not only the measurement of solar azimuth but also reference to an internal clock. Humans cannot do this without artificial instruments. Furthermore, even on cloudy days, migrating monarchs fly in the proper direction (generally south-southwest). Apparently, they also have evolved a backup navigation system, perhaps a geomagnetic compass. (Perez, Sandra M., et al' "A Sun Compass in Monarch Butterflies," Nature, 387:29, 1997.) Comment ...
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... Science Frontiers ONLINE No. 95: Sep-Oct 1994 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The urge to replicate: part i The inside front cover of the March 1944 issue of BioScience displays five pairs of colorful butterflies. Each member of each pair is virtually a duplicate of its partner in shape, design, and colors. Yet, each member of each pair is a different species. Although the pairs are from the same geographical regions, it is not obvious why this astounding mimicry should occur. Here, one cannot invoke the explanation that one species gains an evolutionary advantage by mimicking an unpalatable species, as with mimics of the Monarch Butterfly. That is, there seems to be no evolutionary advantage to looking alike. (Miller, Julie Ann; BioScience, inside front cover, March 1994. Miller's editorial remarks are based upon a later article by H.F . Nijhout, who also supplied the photographs. Nijhout's article explains how butterfly wing patterns may have evolved.) Comment. Cases of remarkable mimicry also occur among geographically separated species. For example, the North American Meadowlarks are dead ringers for the African Yellow-throated Longclaw. "Convergent evolution" names the phenomenon but doesn't tell how or why long chains of random mutations can come up with the same designs where there seems to be no "guidance" by the forces of natural selection. Perhaps genomes contain "subprograms" for those patterns and structures often used in biology. Of course, Sheldrake's idea of ...
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... Science Frontiers ONLINE No. 16: Summer 1981 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Plants Manufacture Fake Insect Eggs Plants are usually considered rather passive to environmental forces, but careful observation show that they fight back against predators in subtle ways. Williams and Gilbert, for example, have found that a number of Passiflora species, which are heavily defoliated by the larvae of Heliconius butterflies, have developed tiny structures that closely resemble in size, shape, and color the eggs of these butterflies. Heliconius butterflies, when searching for likely plants on which to lay eggs, tend to avoid plants that already have eggs on them. The plants' fake eggs, then, help protect the plant from predation. (Williams, Kathy S., and Gilbert, Lawrence E.; "Insects as Selective Agents on Plant Vegetative Morphology....."; Science, 212:467, 1981.) Comment. We have heard over and over again about Nature's "marvelous adaptations," but it is still difficult to imagine chance-driven evolution of fake eggs of just the right size, shape, and color. How many shapes and colors were tried before the plants got it right? From Science Frontiers #16, Summer 1981 . 1981-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 50: Mar-Apr 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Monarchs slighted -- sorry!Contrary to the report in SF#49, at least one tagged monarch butterfly has been found among the wintering colonies in Mexico. In early 1976, a tagged individual from Chaska, Minnesota, was indeed found among a huge cluster in Mexico. Also, a few butterflies tagged in the northern states have turned up in Texas, well on their way to Mexico. (Urquhart, Fred A.; "Found at Last: The Monarch's Winter Home," National Geographic Magazine, August 1976. Cr. B. Ickes) Comment. So, it seems that A.M . Wenner, the University of California researcher, will have to correct his records and perhaps modify his theory. From Science Frontiers #50, MAR-APR 1987 . 1987-2000 William R. Corliss ...
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... it disguises some of its leaves as fruits. Young plants produce only the long, needle-shaped leaves. But mature five-year-old shrubs also grow broad leaves that cluster around the slightly smaller, almost identical-looking green seed-filled fruits." When offered branches stripped of real leaves and bearing just fruits, the cockatoos quickly demolished them. Normal branches bearing both leaves and fruit were attacked at first -- especially the larger leaves. But when the cockatoos found themselves duped a large proportion of the time, they gave up in obvious frustration. (Anonymous; "Fruit Dupes," Discover, 15:16, August 1994.) Comment. An even more amazing case of plant mimicry occurs among Passiflora species, which craft precise copies of the eggs of a butterfly, whose larvae decimate these plants. The butterflies see the fake eggs and go look for places to lay their eggs where there is less competition. (See SF#16) From Science Frontiers #97, JAN-FEB 1995 . 1995-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 71: Sep-Oct 1990 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Those Amazing Insects Scientific creationists often point out marvels of biological engineering as proofs that evolution by small chancedirected steps is, to say the least, improbable. A sharp arrow for their qui ver has just appeared in Science. Caterpillar-ant vibrational communication. Some species of caterpillars cannot survive predation unless they are protected by ants. To attract the ants, who just happen to dote on special secretions of the caterpillars, the caterpillars send out vibrational signals across leaves and twigs. In addition to their secretory structures, the caterpillars have also evolved novel vibrators to send out their calls for protection. A few butterfly species from all continents (except Antarctica) have evolved these devices. Looking at this geographical spread, P. J. DeVries thinks that the two sets of organs must have developed independently at least three times . (DeVries, P.J .; "Enhancement of Symbioses between Butterfly Caterpillars and Ants by Vibrational Communication," Science, 248:1104, 1990.) From Science Frontiers #71, SEP-OCT 1990 . 1990-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 120: Nov-Dec 1998 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Bye-bye Mercury, and Maybe Mars During the 1950s, the campaign of mainstream science to discredit Velikovsky assured the public that the solar system was the epitome of stability -- wayward planets were impossible. Then along came chaos theory which implied that the flight of a butterfly in Brazil could, in principle, affect weather in Canada. In effect, a slight change in initial conditions could, in the fullness of time, have very large effects. Now, it is generally admitted that the solar system is chaotic after all. Each planet is subject to the tiny, butterfly-like gravitational tugs of the other planets, especially Jupiter. Given enough time, these gravitational nuances can result in the ejection of a planet from the solar system -- and may already have done so in the past! Mercury and Mars are the most vulnerable on a billion-year time scale. In the case of Mercury, its orbit will become more and more elliptical according to computer simulations. Eventually a close gravitational encounter with Venus is possible. This could send Mercury careening off into deep space. The probability of this happening is only 1 in a 1000 over 5 billion years, but it is not zero. Mars might likewise be ejected by a passing nudge from earth. However, this encounter could go the other way. Depending upon the celestial dynamics of the encounter, Mars might gravitationally fling earth out into the Galaxy, and ...
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... photoreceptors. Photoreceptors are sensitive to light but do not produce images. They are found in many groups of animals. Even humans possess photoreceptors besides their eyes; specifically, in the pineal gland and, perhaps, the knees. (SF#116, SF#117) The pineal gland (our "third eye") may have registered photons at some stage in our evolution, but it is now useless or adapted to other purposes. The arthropods, however, still find photoreceptors useful. Crayfish have them on their abdomens, where they initiate an escape response when illuminated. Additionally, the blind shrimp that collect around the glowing deep-sea vents have photoreceptors perched on their backs, presumably to guide them to their prey located around the luminous vents. Recently, the Japanese yellow swallowtail butterflies were discovered to sport photoreceptors on their genitalia. These I are used during mating to confirm the position of the female's ovipositor.(Arikawa, Kentaro; "Hindsight of Butterflies," BioScience, 51:219, 2001.) Barn-Owl auditory neurons multiple signals. Barn Owls can locate rustling mice in the dark with high precision. They discern their prey by sound rather than light. To achieve the high accuracy needed to home in on small rodents in the black of night, their ears are slightly offset so that they can draw a bead by using microsecond time-of-arrival differences in the sounds coming from the target. To increase the owl's passive sonar, their auditory neurons multiply the signals instead of adding them as do other neurons. In ...
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... Science Frontiers ONLINE No. 49: Jan-Feb 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Monarch Migration An Illusion "The epic autumn migration of the eastern monarch butterfly to wintering grounds in Mexico, where millions cluster on trees in semi-dormancy to await spring, has become known as one of the standard 'wonders of nature' in the decade since the Mexican winter clusters were found." There are, however, some flies in this ointment: Monarchs tagged in the north have never been found in the Mexican clusters. Fall-fattened monarchs can store only enough energy for a flight of about 200 miles -- far too short, unless they refuel along the way (no one knows if they do or not); and The monarchs seen in Mexico are almost always in pristine condition and show no wing wear or tattering. A.M . Wenner, University of California at Santa Barbara, thinks that the "appearance" of mass migration reported frequently from many locales may just be due to a curious fall habit of the monarchs. It seems that widely scattered individuals begin to fly into the wind, and the wind concentrates and channels them to local roosts where they spend the winter. In other words, there is no long distance migration at all. (Rensberger, Boyce; Washington Post, September 15, 1986. Cr. J. Judge) From Science Frontiers #49, JAN-FEB 1987 . 1987-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 85: Jan-Feb 1993 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Singing Caterpillars Actually, the singing caterpillars are not particularly tuneful. They really generate a vibration that is transmitted through the material they are resting on. You and I cannot hear caterpillar songs, but some ants can, and they are attracted to these insect sirens. The singing caterpillars belong to the Lycaenidae, which include such butterflies as the hairstreaks and blues. It is not only the singing or vibrating of this group of caterpillars that makes them remarkable, it is the complexity of their symbiotic relationships with several species of ants and a plant. Since both the ants and the caterpillars favor the Croton plant, they could well meet by chance, but the caterpillars' singing serves to accelerate contact. Once met on the Croton plant, a fascinating triangle is completed. Player 1. The Croton plant provides nourishment to the caterpillars through both its leaves and specially evolved nectaries (nectar-producing organs), but receives nothing in return. The ants also dote on the nectaries, but they at least protect the plant from all herbivorous insects except the singing caterpillars. Player 2. The ants get food from both the Croton plant and the caterpillars. The latter have evolved extrudable glands called "nectary organs." For their part of the bargain, the ants protect the caterpillar from predatory wasps, just as they defend the Croton plant from its enemies. Player 3. The caterpillars, though seemingly benign, are the heavies in this ...
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... messages from God, predictions of future events, marks of spiritual favor, etc. Kroll and Bachrach concluded that in the Middle Ages visions were culturally supported phenomena and not evidences of psychological illness, as they are today. (Kroll, Jerome, and Bachrach, Bernard; "Visions and Psychopathology in the Middle Ages," Journal of Nervous and Mental Disease, 170:41, 1982.) Comment. Superficially there is little that is surprising in these results. The people of the Middle Ages had wider spiritual horizons, while we build mental hospitals and consider UFO contactees as nuts. Regardless of the cultural environment, visions keep on occurring. They virtually never have any practical import. Why, then, do we keep on seeing them? Waxing speculative again, the false-head butterflies mentioned on p.000 probably have no inkling about the real value of their markings; is there some yet uncomprehended purpose behind these strange human mental quirks, or are they merely a little snow on our TV screens? From Science Frontiers #20, MAR-APR 1982 . 1982-2000 William R. Corliss ...
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... . The arguments against the "genes-are-everything" paradigm are long and complex, but Cohen and Stewart also provide some simple, possibly simplistic observations supporting a much broader view of genetics. Mammalian DNA contains fewer bases than amphibian DNA, even though mammals are considered more complex and "advanced." The implication is that "DNA-as-a -message" must be a flawed metaphor. Wings have been invented at least four times by divergent classes (pterosaurs, insects, birds, bats); and it is very unlikely that there is a common DNA sequence that specifies how to manufacture a wing. The connections between the nerve cells comprising the human brain represent much more information than can possibly be encoded in human DNA. A caterpillar has the same DNA as the butterfly it eventually becomes. Ergo, something more than DNA must be involved. [This observation does seem simplistic, because DNA could, in principle, code for metamorphosis.] Like DNA, this "something more" passing from parent to offspring conveys information on the biochemical level. This aspect of heredity has been by-passed as geneticists have focussed on the genes. Cohen and Stewart summarize their views as follows: "What we have been saying is that DNA space is not a map of creature space. There is no unique correspondence between the two spaces, no way to assign to each sequence in DNA space a unique animal that it "codes for." Biological development is a complicated transaction between the DNA "program" and its host organism, neither alone can construct a ...
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... Science Frontiers ONLINE No. 39: May-Jun 1985 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Shrimp trains are a'coming In March's "Gallery" pages of Discover, several incredibly colored and patterned shrimp stun the eyes of the reader. Some of these shrimp put the gaudiest butterflies and birds to shame. We won't stop here to dwell on why some shrimp are so colorful while others are so tasty. The anomaly at hand is buried in the caption describing the red-andwhite striped peppermint shrimp, which decorates the Great Barrier Reef. It turns out that this shrimp, like the Atlantic spiny lobster, sometimes joins up with others of its species to form long moving trains or chains of animals. This behavior remains very puzzling to biologists. (Anonymous; "Shrimp You Won't Find in Your Cocktail," Discover, 6:55, March 1985.) Comment. Do shrimp belong with the insects? Yes, they are all arthropods. From Science Frontiers #39, MAY-JUN 1985 . 1985-2000 William R. Corliss ...
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... well with that estimated from larvae. Such a discrepancy for different stages has occasionally been reported within families of insects, and it has an apparent resemblance to the discordance occasionally found between phylogenies inferred from morphological and molecular characters. In such cases, the usual conclusion (I ignore data chauvinists) is that we should somehow use all the available information to infer the correct phylogeny. After all, there was just one real phylogeny that occurred in the past, and we want to find it as closely as we can." Comment inserted by the compiler. Van Valen is saying that three evolutionary Trees of Life can be drawn from adult morphology, DNA structure, and larval morphology, and that they may not look the same. Caterpillars may yield a family tree different from that inferred from the butterflies. Which is correct, or are they all correct? Back to the review. Waxing heretical, Williamson points out that an organism may have more than one phylogeny ! Larvae may have ancestries different from the adults. How heretical can one get? But in the ocean, spermatozoa often cannot find an egg of the correct species. They may then fertilize eggs of a distantly related species. In such "wide hybrids," the larvae may resemble one parent and the adults the other. There is much more. The gist of it all is that evolution has been much more than random mutation and natural selection. Hybridization and outright mergers (endosymbiosis) have played important roles. Even our own cells harbor mitochondria that have their own DNA. They are probably bacterial invaders that long ago ...
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