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  • 1
    Electronic Resource
    Electronic Resource
    Orbital forcing of deep-sea benthic species diversity (1997)
    [s.l.] : Nature Publishing Group
    Nature 385 (1997), S. 624-627 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We examined ostracods from 125 10-ml samples from the deep-sea drilling project (DSDP) site 607, located on the western flank of the mid-Atlantic ridge (41° N, 19° W; water depth, 3,427m), and DSDP site 610 near the Rockall plateau (53° N, 19° W; water depth, 2,417m). Site 607 is ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/385624a0
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  • 2
    Electronic Resource
    Electronic Resource
    The UV visual world of fishes: a review (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ultraviolet-A radiation (320–400 nm) is scattered rapidly in water. Despite this fact, UV is present in biologically useful amounts to at least 100 m deep in clear aquatic environments. Discovery of UV visual pigments with peak absorption at around 360 nm in teleost cone photoreceptors indicates that many teleost fishes may be adapted for vision in the UV range. Considering the characteristic absorption curve for visual pigments, about 18% of the downwelling light that illuminates objects at 30-m depth would be available to UV-sensitive cones. Strong scattering of UV radiation should produce unique imaging conditions as a very bright UV background in the horizontal view and a marked veiling effect that, with distance, obscures an image. Many teleosts have three, or even four, classes of cone cells mediating colour vision in their retina and one can be sensitive to UV. These UV-sensitive cones contain a visual pigment based on a unique opsin which is highly conserved between fish species. Several powerful methods exist for demonstration of UV vision, but all are rather demanding in terms of technique and equipment. Demonstration that the eye lacks UV-blocking compounds that are present in many fish eyes is a simpler method that can indicate the possibility of UV vision. The only experimental evidence for the use of UV vision by fishes is connected to planktivory: detection of UV-opaque objects at close range against a bright UV background is enhanced by the physical properties of UV light. Once present, perhaps for the function of detecting food, UV vision may well be co-opted through natural selection for other functions. Recent discovery that UV vision is critically important for mate choice in some birds and lizards is a strong object lesson for fish ecologists and behaviourists. Other possible functions amount to far more than merely adding a fourth dimension to the visible spectrum. Since UV is scattered so effectively in water, it may be useful for social signalling at short range and reduce the possibility of detection by other, illegitimate, receivers. Since humans are blind to UV light, we may be significantly in error, in many cases, in our attempts to understand and evaluate visual aspects of fish behaviour. A survey of the reflectance properties of skin pigments in fishes reveals a rich array of pigments with reflectance peaks in the UV. For example, the same yellow to our eyes may comprise two perceptually different colours to fish, yellow and UV-yellow. It is clearly necessary for us to anticipate that many fishes may have some form of UV vision.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00848.x
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  • 3
    Electronic Resource
    Electronic Resource
    The eye-movements of the mantis shrimp Odontodactylus scyllarus (Crustacea: Stomatopoda) (1990)
    Springer
    Journal of comparative physiology 167 (1990), S. 155-166 
    Details
    ISSN: 1432-1351
    Keywords: Vision ; Eye-movement ; Stomatopod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Odontodactylus scyllarus makes discrete spontaneous eye-movements at a maximum rate of 3/s. These movements are unpredictable in direction and timing, and there is no detectable co-ordination between the two eyes. The eye-movements were measured with a computer-aided video method, and from 208 of these the following picture of a typical movement emerges. It has roughly equal horizontal and vertical components of 7–8°, taking the eye-stalk axis about 12° around a great circle, and also a rotational component of about 8°. The 3 components can occur independently of each other and are thus separately driven by the brain (Fig. 6). The average duration is 300 ms, and average velocity is 40° s (Fig. 5). Most movements are made in a direction approximately at right angles to the orientation of the specialised central band. It is shown that the slow speed of the eye-movements is compatible with scanning, that is, the uptake of visual information during the movement rather than its exclusion as in conventional saccades. Mantis shrimps also make target-acquiring and tracking eye-movements which tend to be somewhat larger and faster than other spontaneous movements. Rotating a striped drum around the animal induces a typical optokinetic nystagmus whose slow phases are smooth, unlike target tracking which is jerky (Fig. 7). Eye-movements may therefore be conveniently grouped into 3 classes: targetting/tracking, scanning, and optokinetic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188107
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  • 4
    Electronic Resource
    Electronic Resource
    Behavioural evidence for colour vision in stomatopod crustaceans (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 473-481 
    Details
    ISSN: 1432-1351
    Keywords: Stomatopod ; Colour vision ; Crustacean behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract If an organism can be taught to respond in a particular way to a wavelength of light, irrespective of that light's intensity, then it must be able to perceive the colour of the stimulus. No marine invertebrate has yet been shown to have colour vision. Stomatopod crustaceans (mantis shrimps) are colourful animals and their eyes have many adaptations which indicate that they are capable of such spectral analysis. We adopted an associative learning paradigm to attempt to demonstrate colour vision. Stomatopods readily learnt to choose some colours from arrays of greys, even when the correct choice colours were darker than the ones they had been trained to. Possible mechanisms underlying colour vision in these animals, and their ecological significance are discussed. A simple model is presented which may help interpret the complex-stomatopod colour vision system and explain some of the learning anomalies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192314
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  • 5
    Electronic Resource
    Electronic Resource
    Photoreceptor spectral diversity in the retinas of squilloid and lysiosquilloid stomatopod crustaceans (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 339-350 
    Details
    ISSN: 1432-1351
    Keywords: Photoreceptor ; Retina ; Spectral sensitivity ; Stomatopod ; Visual ecology ; Visual pigment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. We examined the retinas of 2 species of stomatopods in the superfamily Squilloidea, Cloridopsis dubia and Squilla empusa, and 2 species of the super-family Lysiosquilloidea, Coronis scolopendra and Lysiosquilla sulcata, using microspectrophotometry in the visible region of the spectrum. 2. Retinas of all species included numerous photostable pigments, such as green reflecting pigment, hemocyanin, colored oil droplets, and vesicles. Both lysiosquilloid species also had intrarhabdomal filters within specialized photoreceptors of the midband. 3. Squilloid species contained a single visual pigment throughout all photoreceptors, with peak absorption at medium wavelengths (near 515nm). Retinas of lysiosquilloids contained a diversity of visual pigments, with estimated λmax values ranging from 397 to 551 nm. 4. Spectral sensitivity functions were estimated for the lysiosquilloid species based on estimates of visual pigment λnax, photoreceptor dimensions, and specific absorbances of the visual pigments and intrarhabdomal filters. Ommatidia of midband Rows 1 to 4 contained pairs of narrowly tuned spectral receptors, appropriate for spectral discrimination, while ommatidia of midband Rows 5 and 6, and all peripheral ommatidia, had broad spectral sensitivity functions. 5. Lysiosquilloid stomatopods have retinas that closely resemble those of gonodactyloids both structurally and in their visual pigment diversity. In contrast, squilloids have retinas that are much simpler. These differences appear to be related to the habitats and activity cycles of species belonging to the 3 major superfamilies of stomatopod crustaceans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216616
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  • 6
    Electronic Resource
    Electronic Resource
    Investigations of pigment granule transport systems in Gonodactylus oerstedii (Crustacea: Hoplocarida: Stomatopoda) (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 323-329 
    Details
    ISSN: 1432-1351
    Keywords: Pupillary response ; Pigment granule migration ; Compound eyes ; Temperature effects ; Stomatopods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Compound eyes of the stomatopod, Gonodactylus oerstedii, exhibit pupillary reflection responses which arise from migration of retinular cell pigment granules. In the light, reflectance from the eye increases as pigment granules accumulate around light-sensitive rhabdoms and scatter incoming light back out of the eye (pupillary closure). At dark onset, reflectance diminishes as pigment granules disperse centrifugally, enhancing photon capture by the rhabdom. We investigated the mechanisms of the pupillary response in intact animals by measuring reflectance from the eye under different temperature conditions. Lowering the temperature from 27° to 7 °C caused an increase in reflectance of infrared light in the absence of visible-light stimuli, indicating pupillary closure. When given light stimuli as temperature decreased, the eye continued to produce reflection increases which decreased in amplitude as the between stimulus reflectance level increased. All low-temperature effects were reversed when temperature was increased to normal. The rate of pupillary closure was insensitive to temperature, with a temperature quotient (Q10) of 0.8 ± 0.1 s.e.m, while pupillary opening was extremely temperature sensitive (Q10 of 5.4 ± 0.4). Different temperature sensitivities for pupillary opening and closing suggest that these processes involve different mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192991
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  • 7
    Electronic Resource
    Electronic Resource
    Tuning of photoreceptor spectral sensitivity in fireflies (Coleoptera: Lampyridae) (2000)
    Springer
    Journal of comparative physiology 186 (2000), S. 1-12 
    Details
    ISSN: 1432-1351
    Keywords: Key words Spectral sensitivity ; Filter ; Firefly ; Compound eye ; Vision ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sexual communication between male and female fireflies involves the visual detection of species-specific bioluminescent signals. Firefly species vary spectrally in both their emitted light and in the sensitivity of the eye, depending on the time when each is active. Tuning of spectral sensitivity in three firefly species that occupy different photic niches was investigated using light and electron microscopy, microspectrophotometry, and intracellular recording to characterize the location and spectral absorption of the screening pigments that filter incoming light, the visual pigments that receive this filtered light, and the visual spectral sensitivity. Twilight-active species had similar pink screening pigments, but the visual pigment of Photinus pyralis peaked near 545 nm, while that of P. scintillans had a λmax near 557 nm. The night-active Photuris versicolor had a yellow screening pigment that was uniquely localized, while its visual pigment was similar to that of P. pyralis. These results show that both screening and visual pigments vary among species. Modeling of spectral tuning indicates that the combination of screening and visual pigments found in the retina of each species provides the best possible match of sensitivity to bioluminescent emission. This combination also produced model sensitivity spectra that closely resemble sensitivities measured either with electroretinographic or intracellular techniques. Vision in both species of Photinus appears to be evolutionarily tuned for maximum discrimination of conspecific signals from spectrally broader backgrounds. Ph. versicolor, on the other hand, appears to have a visual system that offers a compromise between maximum sensitivity to, and maximum discrimination of, their signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050001
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  • 8
    Electronic Resource
    Electronic Resource
    The retinas of mantis shrimps from low-light environments (Crustacea; Stomatopoda; Gonodactylidae) (1994)
    Springer
    Journal of comparative physiology 174 (1994), S. 607-619 
    Details
    ISSN: 1432-1351
    Keywords: Photoreceptor ; Retina ; Spectral sensitivity ; Stomatopoda ; Visual ecology ; Visual pigment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. We examined microspectrophotometrically the retinas of 3 species of stomatopods in the superfamily Gonodactyloidea, all of which live in environments that are reduced both in the intensity and spectral range of natural illumination. Species examined were Odontodactylus brevirostris, O. scyllarus, and Hemisquilla ensigera. 2. All 3 species had the typical gonodactyloid diversity of visual pigments, with 8 different photopigments residing in the 4 tiered rows of the midband and 2 additional types in the untiered classes of photoreceptors in the midband and peripheral retina. The spectral range covered by the λmax values of the visual pigments of each species was similar to that of other gonodactyloid and lysiosquilloid species. 3. Apparent retinal adaptations in species of Odontodactylus for vision in dimly lit, spectrally narrow photic environments were seen primarily as specializations of the intrarhabdomal filters. These were of reduced diversity, and had reduced absorption at long wavelengths compared to the filters of other gonodactyloid stomatopods. Retinas of H. ensigera lacked both proximal classes of intrarhabdomal filter, and had the smallest total range of visual pigment λmax yet observed in mantis shrimps. These modifications decrease the spectral range and number of types of narrow-band spectral classes of phooreceptors, while increasing their sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217382
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  • 9
    Electronic Resource
    Electronic Resource
    Investigations of pigment granule transport systems in Gonodactylus oerstedii (Crustacea: Hoplocarida: Stomatopoda) (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 331-342 
    Details
    ISSN: 1432-1351
    Keywords: Pigment granule migration ; Microtubules ; Compound eyes ; Temperature effects ; Stomatopods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pigment granules within retinular cells of the stomatopod crustacean, Gonodactylus oerstedii, undergo rapid, radial migrations in response to changes in ambient lighting. Light stimulates centripetal migration of pigment granules towards the microvillar rhabdomeres where they absorb and scatter incoming light, analogous in function to the closure of a pupil. In the dark, pigment granules disperse centrifugally away from rhabdoms, thereby opening the pupil. Two populations of microtubules in retinular cells of G. oerstedii are appropriately oriented for participation in pigment granule migration. We investigated the possibility that microtubules are involved in pigment granule migration by subjecting animals to low temperature (which can depolymerize some microtubules) and determining the effects of low temperature on pigment granule position and microtubule density within retinular cells. When temperature was decreased, pigment granules in previously dark-adapted eyes aggregated around rhabdoms, in the light-adapted configuration. Lowering the temperature also decreased the density of palisade microtubules, which extend longitudinally in retinular cells along the subrhabdomeric palisade vacuole. These changes reversed when temperature increased. We present a model for pigment granule migration based on the idea that the position of pigment granules in retinular cells is dependent upon the presence of intact palisade microtubules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192992
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  • 10
    Electronic Resource
    Electronic Resource
    Visual pigment diversity in two genera of mantis shrimps implies rapid evolution (Crustacea; Stomatopoda) (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 371-384 
    Details
    ISSN: 1432-1351
    Keywords: Visual pigment ; Stomatopoda ; Visual ecology ; Evolution ; Photoreceptor ; Retina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. Interspecific diversity in the visual pigments of stomatopod crustaceans was characterized using microspectrophotometry. We examined the 10 visual pigments in main rhabdoms in retinas of 3 species of each of two genera of stomatopod crustaceans of the superfamily Gonodactyloidea, Gonodactylus (G. oerstedii, G. aloha, and G. curacaoensis) and Odontodactylus (O. scyllarus, O. brevirostris, and O. “havanensis”). Species were selected to provide a matched diversity of habitats. 2. In each genus, visual pigments varied in λmax in several regions of the retina, as revealed by analysis of variance. The variation within closely related species of the same genus implies that visual pigments can evolve rapidly in stomatopods. 3. In photoreceptors of the peripheral retina, which are devoted to spatial vision, visual pigment λmax decreased as the depth range of the various species increased, a typical pattern for marine animals. In contrast, visual pigment λmax in photoreceptors of retinal regions devoted to polarization vision (midband Rows 5 and 6) is not obviously correlated with the spectral environment, implying that polarization information may be confined to particular spectral ranges. Visual pigments of the tiered rows of the midband, which are committed to spectral analysis, span a larger spectral range in shallow-water than deepwater species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194991
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