The Selection of Random Movements as a Factor in Phototaxis (original) (raw)
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Light and the Behavior of Organisms
Science, 1911
of speculation in guiding and unifying experimental work; on the other he saw the necessity of founding philosophical speculation on experimental facts. This broad view resulted in much comparative work especially in physiology and psychology, work which had a direct bearing on the nature of psychic processes as well as on the nature of physiological activity. Miiller worked on the higher animals almost exclusively. His aim was to analyze the phenomena of life as he found them in these organisms. His followers, Wohler, Liebig, Helmholtz, du Bois-Reymond, Lotze, Weber, Fechner and others, perpetuated this aim, but they did not retain his breadth of spirit. Some confined their investigations to the chemical side of physiology, others to the physical side, and still others to pure psychology. The question as to the origin and evolution of vital phenomena, especially psychic phenomena, was not 8 HISTORICAL REVIEW 49 not a primitive condition, but a product of development." " To a change leading away from the optimum (in either plus or minus direction)" the organism responds in such a way as to tend to return to the optimum. " Thus are produced the so-called positive and negative reactions." The essential characteristics in behavior, as analyzed by Jennings, are clearly set forth in the following quotations (1906, pp. 283-292). Internal factors: ** Activity does not require present external stimulation.. .. Activity may change without external cause.. .. Changes in activity depend on changes in physiological states.. .. Reactions to external agents depend on physiological states.. .. The physiological state may be changed by progressive internal processes, particularly those of metabolism.. .. The physiological state may be changed by the action of external agents.. .. The physiological state may be changed by the activity of the organism.. .. External agents cause reaction by changing the physiological state of the organism.. .. The behavior of the organism at any moment depends upon its physiological state at that moment.. .. Physiological states change in accordance with certain laws.. .. The resolution of one physiological state into another becomes easier and more rapid after it has taken place a number of times." Different factors on which behavior depends : "We have seen that the behavior of the organism at a given moment depends on its physiological state, and that it therefore secondarily depends upon all the factors upon which the physiological state depends. Hence we cannot expect the behavior to be determined alone by the present external stimulus, as is sometimes maintained, for this is only one factor in determining the physiological state. The behavior at a given moment may depend on the following factors, since these all affect the physiological state of the organism : " I. The present external stimulus. ''2. Former stimuli.
Phototactic Response in Earthworm – “Eisenia foetida”
It is proved that the reactions which are typical of the life in the burrow are more definite and weaker stimuli then reaction in the open, and this may be expresses by saying that the earthworm's organization is more highly adapted for life in the burrow. Reactions in the axial direction a definite and sensitive to stimuli then lateral m response to light.
Journal of Biological Rhythms, 1986
Three night-break experiment protocols were utilized in an attempt to help clarify the role of the circadian system in photoperiodic time measurement in the European corn borer, Ostrinia nubilalis. Larvae raised in a light-dark (LD) cycle consisting of 12 hr of light alternating with 12 hr of darkness (LD 12:12), at a constant temperature of 30°C, enter a state of arrested growth and development known as diapause . In the present research (Experiment 1), the induction of diapause was prevented by 1-hr light pulses that systematically scanned the dark phase of LD 12:12. Thus, the importance of 12 hr of uninterrupted darkness for maximal induction of diapause is stressed. The same experimental protocol applied to larvae already in diapause (Experiment 2), however, resulted in a bimodal curve of diapause termination. Although this result is consistent with the proposition that a nonperiodic hourglass timer underlies this event (Skopik and Takeda, 1986), it does not rule out the circadian system.
Applied Ecology and Environmental Research, 2008
Many news bulletins found in the literature only consent themselves with the description of the night distribution of the trapped species not examining the beginning and the end of the insects' flight towards the light with the measurement of environmental lighting, expressed in lux. For this reason, we had examined the daily appearance of the first and last specimens of the species in the light trap concerning the exact lighting figures. We have used the hourly collection data of the fractionating light trap at the farm of Julianna in Nagykovácsi, belonging to the MTA Crop Protection Research Institute. With the help of our own computer programme we had counted the light coming from the sun, moon and from the starry sky, for every full hour separately and in total. We had given two lighting figures to every trapping data: we had counted the first minute of the first and the next hour of the given hour in lux within which the trapping had happened. Hereby, two lighting figures had become known during which the flight towards lighting had begun and end. The flight of 51 species towards the light happens when the total of the given hour concur in the duration of navigation twilight, of 26 species in the duration of sidereal twilight and of 7 species in the duration of night light. There were 2 species where the first imago was already captured during daylight. In the period of the quick reduction of lighting only the first specimens of the 14 species appear, accordingly: 4 from daylight to civil twilight, 4 from daylight to navigation twilight, 1 from sunset to navigation twilight and 4 species from civil twilight to sidereal twilight. The flight towards light ends in the case of 16 species after midnight during the night light, at 48 species during sidereal twilight and at 28 species at navigation twilight. The flight of only 3 species end when it is clearing up quicker within the given hour, from navigation twilight to daylight. Our results could stop a gap.
The influence of light on locomotion in the gastropodmelibe leonina
Marine and Freshwater Behaviour and Physiology, 2004
In this study, we investigated the effects of light on both the locomotion of intact animals and the swim motor program expressed by isolated brains in the gastropod Melibe leonina. Spontaneous locomotion (crawling and swimming) was examined during a period of natural lighting (L:D) to establish normal behavior, and then under two different light regimes: constant darkness (D:D) and constant light (L:L). In L:D, there was significantly more locomotor activity at night than during the day and this pattern continued in D:D. However, in L:L, activity was substantially reduced at all times. Using isolated brain preparations, we further demonstrated that the swim motor program was rapidly inhibited by light, and that this inhibition was mediated by the eyes. These results indicate that M. leonina displays a nocturnal activity pattern, and that light has a strong inhibitory effect on locomotion in the intact animal and on the swim motor program expressed by the isolated brain.
Locomotor response to light and surface angle in three species of desert fleas
Parasitology Research, 2007
We studied the relocation of newly emerged and fed individuals of three species of desert fleas (Xenopsylla conformis, Xenopsylla ramesis, and Parapulex chephrenis) in response to light and surface angle. We observed flea movements inside of either horizontal or tilted cardboard tubes with different light regime at their ends. Proportion of relocating X. conformis and X. ramesis was significantly higher than that of P. chephrenis. In this species only, adult individuals relocated more frequently than newly emerged individuals, and females relocated more frequently than males. In general, the majority of fleas moved toward light independently of its position in relation to the surface angle. Fleas moved toward light even if it was positioned at the lower end of a tube. When both ends of a tube were darkened, newly emerged Xenopsylla moved randomly toward the upper or lower end of a tube, whereas newly emerged P. chephrenis moved mainly toward the upper end of a tube. Adult P. chephrenis and X. conformis also moved mainly toward the upper end of a tube, whereas adult X. ramesis moved mainly toward the lower end. When both ends of a tube were lighted up, newly emerged females of all species, as well as newly emerged female X. ramesis, randomly relocated toward the upper or lower end of a tube. In contrast, newly emerged males and adults of both sexes of P. chephrenis and X. conformis as well as adult female X. ramesis moved mainly toward the upper end of a tube, whereas adult male X. ramesis moved mainly down. Results of this study suggest that light is a more important abiotic signal for flea orientation than surface angle, and there are species-specific differences in flea responses to light and angle stimuli. These differences are related to spatial ecology and behavior of fleas' main hosts as well as to fleas' environmental preferences.