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Millipedes may cause unexpected damage when they are introduced to new locations, becoming invaders that leave behind their old parasites and predators. Therefore, it was interesting to find numerous rhabditid nematodes within the gut of the invasive phytophagous millipede Chamberlinius hualienensisWang, 1956 (Diplopoda, Paradoxosomatidae) from Hachijojima (Japan) in November, 2014. This millipede originated in Taiwan but was discovered in Japan in 1986. The nematodes were identified as juvenile Oscheius rugaoensis(Zhang et al., 2012) Darsouei et al., 2014 (Rhabditidae), and juvenile and adult Mononchoidessp. (Diplogastridae) based on images, morphometrics, and sequences of 18S and 28S rDNA. A novel short 28S sequence of a separate population of Oscheius necromenusSB218 from Australian millipedes was also included in a phylogenetic comparison of what can now be characterized as a species complex of millipede-associated Oscheius. The only other nematode associates of millipedes belong to Rhigonematomorpha and Oxyuridomorpha, two strictly parasitic superorders of nematodes. These nematode identifications represent new geographic and host associations.

Indian tribals use insects in a variety of ways. Species containing valuable protein, easily digestible fats, and considerable amounts of vitamins and minerals are consumed; others serve as raw material for folk remedies. Such uses need to be documented, because tribal communities are increasingly discarding their age-old practices. Research into this field can benefit India and the rest of the world in several ways. Traditional communities need to be shown to appreciate the value of their customs and that to look after their environment (lest many of the useful insects will disappear) is not a luxury, but a necessity. Moreover, studying food insects and therapeutically important species can lead to economic spin-offs and would allow countries like India to develop ways to sustainably use this abundant natural resource.

Background: References to insects in myths, stories, and idioms can be found in almost any culture, but with regard to references involving honey bee species in the Asia-Australian region, little information is available. Such references to bees can be highly informative by revealing attitudes of admiration, fear, ignorance, or even revulsion towards these insects. Results: The subject is briefly reviewed and examples of references to bees of selected cultural communities are given. Although folkloristic references to honey bees were found to be mostly positive highlighting fearlessness, cleverness, and industriousness of the bees, some also touch upon their ability to cause pain. Conclusions: Owing to the decreasing contacts and increasing alienization regarding insects generally, a plea is made to collect whatever information is still available about references to bees in songs, myths, stories, proverbs, and idioms and to compare such uses from different regions, e.g., North and South Korea. This would support other fields of research aiming to discover and to describe cultural relationships, migrations, and contacts between different peoples of the Asian/Australian region.

Abstract: This paper presents a hypothesis that could explain why blue light appears to dominate non-image-forming (NIF) ocular photoreception in marine as well as terrestrial vertebrates. Indeed, there is more and more evidence suggesting that ‘novel’ retinal photoreceptors, which are sensitive to blue light and were only discovered in the 1990s, could be a feature shared by all vertebrates. In our view, blue light photoreception evolved and persisted as NIF photoreception because it has been useful in the colonisation of extensive photo-dependent oceanic habitats and facilitated the move of vertebrates from an aquatic to a terrestrial environment. Because the available scattered evidence is compatible with the validity of our hypothesis, we hope that our rationale will be followed up. Indeed, it (1) involves testable predictions, (2) provides plausible explanations for previous observations, (3) unites phenomena not previously considered related to one another and (4) suggests tests that have not been carried out before. Overall, our approach not only embraces cross-disciplinary links; it, moreover, serves as a reminder of an all-embracing evolutionary history, especially with regard to a ubiquitous photoreceptive ‘clockwork-blue’ in marine and terrestrial vertebrates.

To investigate whether sleep disturbances are associated with C-reactive protein (CRP) levels at the population level. Elevated CRP levels have been found to accompany sleep disturbances, but evidence so far comes only from limited clinical and experimental studies; epidemiological studies are lacking.

To investigate whether the association between insulin resistance (IR) and depressive symptoms is present already in young adult males. The association between IR and depression has been poorly studied, although the existence of a connection of Type II diabetes with depression is well established. We previously demonstrated at epidemiological level in two groups of men aged 31 years and 61 to 63 years that IR is linked with depressive symptoms.

Abstract: The lateral ocelli of Scolopendra cingulata and Scolopendra oraniensis were examined by electron microscopy. A pigmented ocellar field with four eyes arranged in a rhomboid configuration is present frontolaterally on both sides of the head. Each lateral ocellus is cup-shaped and consists of a deeply set biconvex corneal lens, which is formed by 230–2,240 cornea-secreting epithelial cells. A crystalline cone is not developed. Two kinds of photoreceptive cells are present in the retinula. 561–1,026 cylindrical retinula cells with circumapically developed microvilli form a large distal rhabdom. Arranged in 13–18 horizontal rings, the distal retinula cells display a multilayered appearance. Each cell layer forms an axial ring of maximally 75 rhabdomeres. In addition, 71–127 club-shaped proximal retinula cells make up uni- or bidirectional rhabdomeres, whose microvilli interdigitate. 150–250 sheath cells are located at the periphery of the eye. Radial sheath cell processes encompass the soma of all retinula cells. Outside the eye cup there are several thin layers of external pigment cells, which not only ensheath the ocelli but also underlie the entire ocellar field, causing its darkly pigmented. The cornea-secreting epithelial cells, sheath cells and external pigment cells form a part of the basal matrix extending around the entire eye cup. Scolopendromorph lateral ocelli differ remarkably with respect to the eyes of other chilopods. The dual type retinula in scolopendromorph eyes supports the hypothesis of its homology with scutigeromorph ommatidia. Other features (e.g. cup-shaped profile of the eye, horizontally multilayered distal retinula cells, interdigitating proximal rhabdomeres, lack of a crystalline cone, presence of external pigment and sheath cells enveloping the entire retinula) do not have any equivalents in scutigeromorph ommatidia and would, therefore, not directly support homology. In fact, most of them (except the external pigment cells) might be interpreted as autapomorphies defining the Pleurostigmophora. Certain structures (e.g. sheath cells, interdigitating proximal rhabdomeres, discontinuous layer of cornea-secreting epithelial cells) are similar to those found in some lithobiid ocelli (e.g. Lithobius). The external pigment cells in Scolopendra species, however, must presently be regarded as an autapomorphy of the Scolopendromorpha.

Contrary to most other Diptera, the inter-rhabdomeral spaces of the retina of the Jamaican cavefly Neoditomya farri are filled neither by extracellular matrix nor dense cytoplasmic material. Instead, a foamy organization of loose vacuoles, measuring approximately 0.7 µm in diameter, appears to keep the rhabdomeres of retinula cells 7 and 8 in place. The vacuoles are bounded by membranes and traces of actin, determined immunocytochemically, are present. The origin of the vacuoles is unclear, but evidence in support of a retinula cell rather than cone cell origin is advanced. [ABSTRACT FROM AUTHOR]

Summary.:  Our immunocytochemical observations reveal that the muscle present in the tips of the arms of the Antarctic cushionstar Odontaster validus contains caldesmon and calponin but not troponin. Thus, the muscle clearly belongs to the smooth muscle category. Distributions of contractile proteins such as actin, myosin (the latter a typical vertebrate muscle filament protein), paramyosin, and miniparamyosin (the latter two being characteristic of thick invertebrate muscle filaments) were also determined immunocytochemically. The results suggest that the thin filaments of the starfish smooth muscle are similar to those of the vertebrate muscle, but that the thick filaments differ from those of vertebrates and possess traits that are also seen in the muscle organization of invertebrates. The absence from the O. validus muscle of titin and nebulin, proteins so far known almost exclusively from the striated vertebrate muscle, comes as no surprise, but immunoreactivity to mini-titin (a protein of the same family as titin and its replacement in invertebrates) was strong and unambiguously recognizable between filaments. Odontaster validus' histochemical characteristics may be a reflection of the phylogenetic position of the echinoderms as deuterostome invertebrates or they may express an adaptation of the muscle to the harsh environmental conditions under which it has to function in the Antarctic water.

Objective. To assess the demographic and psychosocial profiles of patients with rheumatoid arthritis (RA) who committed suicide. Two control groups were used: osteoarthritis (OA) and suicide victims with neither RA nor OA.Method. A study based on a prospective, 13‐yr follow‐up database with linkage to national hospital discharge registers of all suicides (1296 males, 289 females) committed during the years 1988–2000 in the province of Oulu situated in northern Finland.Results. Females were significantly over‐represented among RA patients who committed suicide (52.6% RA women vs 17.3% women with neither RA nor OA). Comorbid depressive disorders preceded suicides in 90% of the female RA patients. Before their suicide, 50% of the female RA patients (vs 11% of the male RA patients) had experienced at least one suicide attempt. The method of suicide was violent in 90% of the RA females. RA males were less often depressive, but committed suicide after experiencing shorter periods of RA and fewer admissions than females.Conclusion. Attempted suicides and especially depression in female RA patients should be taken more seriously into account than previously in clinical work so that the most appropriate psychiatric treatment can be provided for such patients.

Abstract. No morphological clues on the amphipod head indicate the existence of ocelli. However, as in several isopod species studied so far, two rudimentary photoreceptors are integrated into the medio‐dorsal part of the brain. This electron microscopical study of the photoreceptors is the first report on the presence of ocelli in amphipods. Each ocellus is made up of 3 receptor cells which contribute to the formation of a photoreceptive surface (the rhabdom) formed by tightly packed microvilli. The rhabdoms are twisted and irregular in outline. Membrane turnover is suggested by the presence of different kinds of lysosomes. Lacking dioptric lenses, these photoreceptors are not likely to be involved in image formation but may function as appraisers of ambient light intensity. Physiological and behavioral studies will, henceforth, have to take into account these unexpected ocelli, which may represent remnants of the naupliar eye.

Light-adapted eyes of two freshwater gastropods with similar habitat preferences (Latia neritoides (Gray 1850) and Ancylus fluviatilis (Muller 1774)) were compared with each other in relation to optics, anatomy, and ultrastructure. Individuals of L. neritoides not only possess significantly larger eyes than similarly sized A. fluviatilis, they also have a more voluminous layer of photorecep-tive membranes and appear capable of discerning at least some crude shapes. The eye of A. fluviatilis, on the other hand, has a very shallow retina which is so closely apposed to the lens that it can be little more than an indicator of light and darkness. Both types of eye are generously endowed with screening pigment granules and exhibit no signs of light-induced damage. Although the lenticular F-values for L. neritoides (1.78) and A. fluviatilis (1.74) alone are hardly indicative of an adaptation to a dark environment, the greater amount of photic vesicles and the substantial development of muscle fibres in the eye of L. neritoides suggest that the latter can adjust its vision more rapidly to changing light levels than that of A. fluviatilis. Since L. neritoides (but not A. fluviatilis) has the ability to secrete a bright green luminescent mucus, a faster accommodation system would serve the species well. There is, however, no proof that in Latia bioluminescence alone has been responsible for the development of a more capable eye. Most of the differences between the eyes of L. neritoides and A. fluviatilis can be explained by the distinctly greater nocturnal activity of L. neritoides in combination with the ability to produce bright light in the latter species.

Visual membranes of the crayfish eye either belong to the small, distally placed rhabdomere of retinula cell R8 or are part of the much more voluminous proximal rhabdom, made up of rhabdomeres belonging to cells R1–R7. Under various conditions of environmental stress (e.g., prolonged darkness, elevated temperature, bright light with and without a concomitant rise in temperature, flickering lights) the visual membranes of R8 prove far more resistant to structural damage than those of R1–R7. Membrane damage is known to occur when dormant lipoxygenases become activated, for example through heat. Since R8 is the only type of visual cell in the crayfish retina that does not contain grains of screening pigment, the view that screening-pigment granules could “aggravate” or even “trigger” membrane damage in times of stress is strengthened. Functionally, R8's strong resistance to physical damage when exposed to flickering lights points to a role of the distal rhabdom in the movement detection system of the crayfish eye.

Abstract: The ultrastructure of the nauplius eye of the tiny Antarctic ostracode Acetabulastoma sp. is described and conclusions about its possible function are drawn. Each of the three eye-cups measures approximately 20 μm in diameter and is optically isolated from its neighbour by screening pigments, which are contained in pigment cells behind a tapetum of concentrically arranged, ca. 1-μm-long and 0.1-μm-thick, crystals. Three and sometimes four separate rhabdoms with microvilli measuring 50–60 nm in diameter project from the concave side of the tapetum up to 5 μm deep into the eye-cup interior, which is filled by the retinula cell bodies with their spherical nuclei and various organelles. Desmosomes and microtubules are seen and light-induced cell or membrane damage was minimal. The observations suggest that the Acetabulastoma eye has photoreceptors that can tolerate an exposure to bright light and it may be used to inform its owner of the approach of danger, the depth of water, and/or the season.

AbstractUltrastructural investigations showed that amongst all the hymenopteran eyes examined to date, those of the bumblebee and honeybee exhibit the greatest similarity. Ommatidia in both species are of the apposition type. Minor, but nonetheless noteworthy differences, include the lack of interfacetal hairs in the bumblebee, the rather smooth and flat outer corneal surface, the relatively thick cornea and the larger rhabdoms and retinula cells in the bumblebee eye. Twisting of the rhabdoms or rhabdomeres was not seen. Intracellular electrophysiological responses provided the basis for study of flicker fusion frequency and absolute, polarization, spectral and angular sensitivites.The bumblebee compound eye has a flicker fusion frequency of approximately 130 Hz. Twin flashes resulted only in two distinct responses when the light levels were low. Bright light tended to lead to a suppression of the second depolarization in a twin flash response. Beyond a certain critical brightness, visual cells can no longer simply respond with a potential increase to an increase in light intensity; instead, they react with an increase in response area and a prolonged depolarization afterpotential. Since the latter disappears when the frequency of stimulation is raised, neither the Bunsen-Roscoe law nor the Weber-Fechner response/stimulus intensity relationship can be used to fully describe this phenomenon.Three basic types of retinula cells were found electrophysiologically: II cells possessed a singular sensitivity peak in the ultraviolet (353 nm), 10 cells had a clear peak in the blue (430 nm) and a secondary one in the ultraviolet, and 54 cells exhibited greatest sensitivity in the green to light of 548 nm wavelength. Green-sensitive cells had a secondary peak in the ultraviolet.Polarization sensitive cells were found only amongst ultraviolet and blue cells, but both spectral groups also contained the same number of polarization insensitive cells. It is believed that ultraviolet, blue and green cells can all occur in the same ommatidial unit but that it is unlikely that different visual pigments are housed in the same visual cell. Electroretinogramme recordings were used to measure angular and spectral response curves of the dorsal ocellus.The eye of the bumblebee appears adapted to carry out quick angular flight manoeuvres in bright sunlight. The larger rhabdom and acceptance angle, on the other hand, must give the bumblebee an advantage over the honeybee to forage in somewhat dimmer ambient light conditions. It is concluded that bumblebees, like honeybees, make use of shapes and colours of flowers, use in navigation the polarization pattern of the sky, and that their temporal and spatial resolution allows them to retain relatively fine details of their environment.

Summary Depending on the pre-experimental treatment, densities as well as sizes of particles associated with the visual membranes in the eyes ofProcambarus clarkii varied. The highest mean particle density (5268 ± 969 µm2) and the smallest mean particle diameter (5.57 ± 1.35 nm) were found in crayfish which had been kept in the dark for 10 weeks in aerated fresh water of 10 ° C. Crayfish kept under a 12 h dark/light regime in water of 10 ° C or 30 ° C for three weeks displayed particle densities of 1076 ± 180 and 2899 ± 249 µm-2, respectively; particle diameters were of the order of 8 nm.

This paper presents an account of retinal ultrastructure in three species of the archaic anuran genus Leiopelma. The Leiopelmaretina is approximately 150 µm thick from the inner limiting to Bruch's membrane, and has the layered structure typical of vertebrates. It has large and uniform rod photoreceptors, varying between 50–65 µm in length and 914 µm in diameter. L. archeyiand L. hochstetterihave a few cone cells (under 10% of the total) associated with paraboloid or ellipsosome-like structures in the inner segments. We did not see cone outer segments in L. hamiltoni, although there was a typical cone paraboloid, which suggests that cones are present, albeit in very small numbers. In all three species the retinal pigment epithelium contained numerous organelles, notably fasciculated smooth endoplasmic reticulum, elongated screening pigment grains, and pieces of shedded outer segment discs in all stages of internalisation. On the basis of interspecific comparison, we concluded that the eyes of all three species are principally adapted to operate under low intensities of light; but that of the three, L. archeyiwould be the least nocturnal species. We calculated a density of 1010 photopigment molecules per rod outer segment disc in the eye of L. hamiltoni, and believe that the typical amphibian rod outer segment with large diameter and numerous radial incisures has not changed since the ancestors of extant amphibians first began to conquer solid ground 300 million years ago.

The structural organization of the eye of the dung beetle Onthophagus posticuswas investigated by light and electron microscopy and compared with that of other scarabaeid beetles in an effort to relate eye anatomy and life style. The eye of O. posticusdisplays features like well-developed crystalline cones, presence of a clearzone, and fused rhabdoms of 7 rhabdomeres, which are in line with the phylogenetic and taxonomic position of this species. However, a slight departure from a strictly nocturnal mode of life is indicated by the high degree of orthogonally-arranged rhabdom microvilli of approximately 50 nm in diameter and the absence of a tracheal tapetum. It is concluded that the basis for e-vector detection is present in O. posticus, and, therefore, astro-orientation to maintain a straight path is possible. The division of the eye into a narrow dorsal sliver and a major ventral part is noted, but its functional reason remains enigmatic.

1.Intracellular responses to 30 µs flashes of 11 different spectral lights have been recorded from 75 retinula cells belonging to the eyes of 12 blumblebees.2.Three basic types of retinula cells were found: 11 cells possessed a singular significant peak in the UV (353 nm), 10 cells had a clear peak in the blue (430 nm) and a secondary peak in the UV, and 54 cells exhibited greatest sensitivity in the green to light of 549 nm wavelength.3.Cells sensitive to green light possessed a secondary peak in the UV which reached 75% of the maximum amplitude at ?max, when the flash quantum content was 2.4 ± 0.06×1010. However, when the light intensity was reduced to 12% of this value, the secondary peak in the UV fell to 50% of the ?max response (obtained with the dimmer light).4.By using a method developed by Menzel (1975), it was possible to show that in the bumblebee eye all spectral cell types can occur in the same ommatidial group.5.ERG-recordings from the median ocellus resulted in a double-peaked spectral efficiency curve with a maximum at 353 nm and a secondary peak at 519 nm.6.The electrophysiologically determined spectral efficiency curves were compared with peaks obtained by optical means (Bernard and Stavenga, 1978). Congruity existed only for spectral response maxima from the UV receptor.

Summary:

Abstract: The ultrastructural state of the crayfish visual membrane is correlated with its fatty acid composition during times of photic and thermal stress and the period over which the dynamic events occur is investigated. Crayfish kept at 4 °C under constant darkness contain in their rhabdoms significantly increased amounts of unsaturated fatty acids such as 16:1, 18:1, 20:5, and 22:6 compared with individuals kept at 25 °C. The ratio of unsaturated/saturated fatty acids (UFA/SFA-ratio) amounts to 2.17 in the cold-water- and 1.46 in the warm water-acclimated animals. The visual membranes of crayfish suddenly transferred from 4 °C to 25 °C exhibited ultrastructural modifications such as membrane collapse and disappearance of microvillar dense␣core-filaments most clearly 3 h post-transfer. Parallel to the structural changes a significant increase in fatty acid 18:0 was observed, while the amounts of 16:1 and 20:1 decreased. When 4 °C, dark-adapted crayfish were exposed to light alone and not a temperature increase, only fatty acid 22:6 showed a significant reduction to 10% of its pre-experimental level within 2 h of exposure. Thereafter, it slowly increased again. In cold water-acclimated crayfish that had been exposed to light of 5000 lx for 3␣weeks no significant change of the UFA/SFA ratio was observed, although fatty acid species 18:0, 20:4, and 20:5 had increased at the expense of fatty acids 14:0, 16:0, 16:1, 18:1, 20:1, and 22:6. The total amount of fatty acids, however, had become significantly smaller (from 0.058 ng g−1 body weight in the dark-adapted to 0.048 ng g−1 in the light-adapted crayfish). Morphologically the rhabdom volume had decreased by approx. 20%, but ultrastructurally rhabdom microvilli remained almost unchanged. The amount of peroxidized lipids in the retina following irradiation with bright white light in the cold-adapted crayfish fell during the first 2 h of exposure from 0.4 nmol g−1 to 0.32 nmol g−1, but after 12 h of exposure had reached a level of 0.48 nmol g−1. Greatest structural abnormalities to the visual membranes occurred when dark-adapted, cold-acclimated crayfish were suddenly subjected to bright light and an increase in water temperature. Under such conditions the microvillar arrangement was disrupted and membrane collapse and disappearance of core-filaments were apparent. Our results provide evidence that the fatty acid composition of the membranes determines to a considerable extent the structural integrity of the photoreceptor, but that it is too simplistic a model to think that peroxidation of membrane lipids alone is responsible for the disintegration of the photoreceptive membranes in the crayfish eye following exposure to bright light.

Abstract: This paper gives the first ultrastructural description of muscle cells in Acetabulostoma sp., a small (less than 1 mm in length) Antarctic ostracod. All muscle cells showed the same ultrastructural pattern: this consisted of mononucleated cells containing a single thick myofibril which was surrounded by numerous mitochondria. The nucleus and most cytoplasmic organelles were also located in the cell periphery. The myofibril showed the ultrastructural pattern of transversely striated muscle. Myofilaments formed well-defined sarcomeres, delimited by Z lines. The average sarcomere lengths were: total sarcomere 4.6  0.9 μm, A band 2.86  0.45 μm (0.178  0.06 μm corresponded to the H band), and I band 1.72  0.58 μm. The myofilament diameters were 5.8  0.3 nm (thin myofilaments), and 14.8  0.68 nm (thick myofilaments). In the same myofibril and in cross sections, some thick filaments appeared homogeneously dense whereas others showed a tubular appearance. Each thick filament was surrounded by 12 thin filaments, and the thin/thick filament ratio was 6/1. The sarcotubular system was well developed and consisted of both transverse and longitudinal components, both running within the myofibril among the myofilaments. The transverse components consisted of 20- to 22-nm-diameter tubules that originated from invaginations of the plasma membrane (T tubules). They penetrated radially throughout each A-I interband and branched inside the myofibril. The longitudinal components consisted of bundles of parallel-arranged sarcoplasmic reticulum saccules running parallel to the myofilaments. Each bundle comprised from three to six 30 to 35-nm-diameter saccules. At the levels of the A-I interbands, the saccules of some bundles fused together to form triads with the T tubules. In the triad, the distance between the sarcoplasmic reticulum tubules and the T tubules was 10–14 nm. The mitochondria were large, presented numerous transverse cristae, and were joined one to another by electron-dense plaques. The muscle cell tips ending beneath the cuticle were connected to a modified epidermal cell by a specialized intercellular junction of the fascia adherens type. This junction occurred at the level of a Z line, and displayed an irregular outline with numerous interdigitations that formed conical projections. The ultrastructural characteristics of the myofibrillar apparatus, the plentiful sarcotubular system and the abundance of mitochondria in Acetabulostoma muscles suggest that this muscle type is concurrently a developed model of both the fast-twitch type and the fatigue-resistant type.

1.Relative retinal amounts in the compound eye of the Antarctic amphipod Orchomene plebs were assessed during conditions of continuous summer daylight every 3 h over a period of 48 h. The habitat of the experimental animal is the bottom of the Ross Sea (78°S; 166°E) down to depths of at least 400 m; water temperature is a constant — 1.8° C. A periodicity of 12 h was detected with relative amounts of 11-cis retinal exhibiting peaks at midday and at midnight and troughs at 7.00 h and 19.00 h.2.The result that 90% of retinoid were insoluble in n-hexane suggests that at least 90% of the measured retinoid were attached to membrane-bound proteins such as opsin.3.Selective light adaptation showed that the visual pigments were thermostable and photoregenerable. The main absorbance peak of rhodopsin, compared with metarhodopsin, seems to be in the longer wavelengths.

Summary Various types of surface microstructures and their distribution in the Giant Antarctic SlaterGlyptonotus antarcticus Eights, 1852, are described in detail. Although no attempt has been made to classify the different kinds of scales, leaf-like modifications, threads and feathery hairs, ideas concerning their origin and their function are presented. At least some of the microstructures described seem involved in discouraging foraminifera and larval stages of sessile organisms to settle upon the cuticle ofClyptonotus.

Red and white muscle in the two Antarctic notothenioid fishes Dissostichus mawsoni and Pagothenia borchgrevinki show a rate of postmortem fall of 0.2 pH units per hour, which is close to the rate reported for mammalian muscle at 30°C, but the plateau value is reached several hours earlier in the Antarctic fish, indicating significantly lower stores of initial glycogen. A few particles, most likely representing glycogen, were seen in P. borchgrevinki white muscle and D. mawsoni red muscle, whereas predictably fewer glycogen still was evident in D. mawsoni white muscle. When large numbers of mitochondria and lipid stores were encountered in combination with a small amount of glycogen, we concluded that aerobic metabolism is dominant and that the two species examined would not use white trunk muscle for sustained or slow swimming. Rapid contractions of white trunk muscle as in prey capture or predator evasion are more likely.

A number of differences exists between the compound eyes of larval and adult rock lobsters, Panulirus longipes. The larval eye more closely resembles the apposition type of compound eye, in which retinula cells and rhabdom lie immediately below the cone cells. The adult eye, on the other hand, is a typical clear-zone photoreceptor in which cones and retinula cell layers are separated by a wide transparent region. The rhabdom of the larval eye, if cut longitudinally, exhibits a “banded” structure over its entire length; in the adult the banded part is confined to the distal end, and the rhabdom is tiered. Both eyes have in common an eighth, distally-located retinula cell, which possesses orthogonally-oriented microvilli, and a peculiar lens-shaped “crystal”, which appears to focus light onto the narrow column of the distal rhabdom. Migration of screening pigment on dark-light adaptation is accompanied by changes in sensitivity and resolution of the eye. Retinula cells belonging to one ommatidium do not arrange into one single bundle of axons, but interweave with axons of four neighbouring facets in an extraordinarily regular fashion.

The eye of the deep-sea penaeid shrimp Gennadas consists of approximately 700 square ommatidia with a side length of 15 µn. It is hemispherical in shape and is located at the end of a 1.5 mm long eye stalk. The cornea is extremely thin, but the crystalline cone is well-developed. A clear zone between dioptric structures and the rhabdom layer is absent. A few pigment granules are found within the basement membrane; otherwise they, too, are absent from the eye of Gennadas. The rhabdom is massive and occupies 50 % of the eye. It consists of orthogonally oriented microvilli (the latter measuring 0.07 µm in diameter) and is 75 µm long. In cross sections adjacent rhabdoms, all approximately 8 µm in diameter, form an almost continuous sheet and leave little space for retinula cell cytoplasm. In spite of a one h exposure to light, rhabdom microvilli show no disintegration or disruption of membranes. Vesicles of various kinds, however, are present in all seven retinula cells near the basement membrane. Bundles of seven axons penetrate the basement membrane. On their way to the lamina they often combine and form larger aggregations.

The ultrastructure of the retinula cells of Ligia exotica changes diurnally and in response to light/dark adaptation. At the low phase of electroretinogram (ERG) amplitude (at noon), the arrangement of microvilli is ordered and the rhabdom is of the open type. An irregular arrangement of microvilli appears at the high phase of ERG amplitude (at midnight), when the rhabdom is of the closed type. The pigment granules disperse at midnight and assemble at noon. A centrally positioned, spike-producing eccentric cell is present in each ommatidium. Spectral response curves based on ERG measurements have two maxima, one to light of 383 nm wavelength, the other at around 520 nm. These two peaks represent the two classes of receptor cells identified by intracellular recordings. The ERG responses to light of 383 nm and 520 nm wavelengths display a diurnal rhythmicity, being high at night and low during the day. However, the responses to green light are more strongly affected than those to ultraviolet light. Consequently, the eye displays a relatively higher ultraviolet-sensitivity during the day, whereas at night sensitivity to green light is increased. This behaviour, which persists in continuous darkness, suggests that an endogenous mechanism is involved in bringing about the observed diurnal morphological and physiological changes in the compound eye of Ligia exotica.

1. This is the first transmission electron microscope description of the retina of a parasitic fish.2. The retina is well supplied with capillaries, some of which occur on the inner surface of the retina. An unusual and possibly primitive type of capillary junction is described.3. The outer segments of the retina of Carapus mourlani, which measure approximately 2 µ in diameter, are of one type only. A certain degree of banking was observed. Outer segments are not isolated from each other by screening pigments; they are, however, surrounded by about 15 calycal processes.4. Typical spheroids or conoids were not seen in the outer plexiform layer. The inner nuclear layer consists of one or two layers of nuclei. The inner plexiform layer is unusually wide and some amacrine synapses can be identified. There are few ganglion cells and the ratio of nuclei in the outer nuclear layer to those of the inner nuclear layer to ganglion cells is approximately 100: 10: 1.5. The eye of C. mourlanicombines features of degenerated photoreceptors, characteristic of cave-organisms, with adaptations which are commonly found in nocturnal and deep-sea forms.6. The visual behavior of the animal indicates that the eye is fully functional in spite of its corneal keratosis and small number of optic nerve fibers.

The approximately 200 µm wide eye of Diastylis rathkeiconsists of two closely apposed eye halves with four lenticular complexes measuring 40 µm in diameter in each. Each lenticular complex consists of a lens rich in 30 nm electron-opaque glycogen-like particles made up of smaller (5-6 nm) subunits, and a rhabdom comprising regularly aligned microvilli. The retinula cell somata, which are in a proximal location, are linked with the distally placed rhabdom via approximately 10 µm thick, cellular strands. The strands are surrounded by cells crowded with reflecting organelles of ca.0.8 µm in diameter.Dark/light adaptational changes affect the position of uniformly spherical organelles measuring 0.4-0.5 µm in diameter and presumed to contain carotenoids, the overall size of the rhabdom, and the diameter of individual microvilli. The latter measure 75 nm in the light-adapted state and 90-120 nm in the dark-adapted state. There is ultrastructural evidence (swollen and abundant endoplasmic reticulum and widely distributed glycogen-like particles) that, under light-adapted conditions, the retinula cells are in a phase of intense metabolic activity.A multilamellar structure, similar in appearance to that found in the organ of Bellonci of other crustaceans, but also resembling a trophospongium, was noticed in close proximity to the eye within the optic lobe. Extracellular electrophysiological recordings obtained with NaCl-filled glass electrodes consisted of a cornea-negative potential change and reached a maximum amplitude of nearly 400 µV to 300 ms flashes of white light.Superimposed spectral response curves from eight different animals, based on a criterion amplitude of 50 µV, were nearly congruent in shape and displayed one single sensitivity peak to light of 512-549 nm in wave length. Intensity/response curves obtained to light of 472, 549, and 628 nm wavelengths and the single spectral sensitivity peak strongly suggest that only one type of excitatory visual pigment is involved in the visual process of D. rathkei.It is concluded that in spite of its tiny size, the eye of D. rathkeicould be useful in the coordination of reproduction and synchronization of vertical migrations.

Male and female individuals of the Baltic Sea, stalk-inhabiting amphipod Dulichia porrecta posses eyes that differ in size and organization. Ommatidial numbers also vary, and in adult male and female specimens amount to approximately 80 and 90, respectively. Ommatidial diameters are larger in males (40-45) μm) than in females (approx. 30 μ.m). Externally, female eyes are covered with a dense pelt of approximately 3-4 μm long and 0.01-0.15 μm thick cuticular hairs, interspersed by up to 8 μm long, filament-containing sensilla of unknown function. An identical structure occurs in males, but there it is less frequent. Eyes of male individuals also have considerably fewer and shorter (0.5 μm) cuticular hairs.Internally, the main difference is the somewhat broader (2.7 versus 2.4 μm) and longer (40-50 versus 32-40 μm) rhabdom in male animals and the significantly greater amount of screening pigment granules in the eyes of females. Anatomical features shared between males and females consist of bipartite crystalline cones, five equally-contributing retinula cells and their rhabdomeres per ommatidium, a perirhabdomal space and two kinds of screening pigment granules. Ultrastructural derangements of rhabdom or microvilli following several hours of exposure to very bright spotlights are not apparent. The rhabdom length/width ratio for both male and female individuals is very high and, despite their essentially sedentary biology, allies D. porrecta most closely with pelagic amphipod species such as Hyperia and Phronima. It is concluded that from a sensory-ecological viewpoint D. porrecta is a species that does not require vision for most of its vital functions, but that it does make use of vision in shallower water to evade predators. Males are likely to have more sensitive eyes than females, but those of the latter may posses greater resolution.

The compound eyes of the mesopelagic euphausiid Thysanopoda tricuspidata were investigated by light-, scanning-, and transmission electron microscopy. The eyes are spherical and have a diameter that corresponds to 1/6 of the carapace length. The hexagonal facets have strongly curved outer surfaces. Although there are four crystalline cone cells, only two participate in the formation of the cone, which is 90–120 µm long and appears to have a radial gradient of refractive index. The clear zone, separating dioptric structures and retinula, is only 90–120 µm wide. In it lie the very large oval nuclei of the seven retinula cells. Directly in front of the 70 µm long and 15 µm thick rhabdom a lens-like structure of 12 µm diameter is developed. This structure, known in only a very few arthropods, seems to be present in all species of Euphausiacea studied to date. It is believed that the rhabdom lens improves near-field vision and absolute light sensitivity. Rod-shaped pigment grains and mitochondria of the tubular type are found in the plasma of retinula cells. The position of the proximal screening pigment as well as the microvillar organization in the rhadbdom are indicative of light-adapted material. The orthogonal alignment of rhabdovilli suggests polarization sensitivity. Behind each rhabdom there is a cup-shaped homogeneous structure of unknown, but possibly optical function. Finally, the structure and the function of the euphysiid eye are reviewed and the functional implications of individual components are discussed.

In Streetsia challengeri left and right eyes have fused and become a single cylindrical photoreceptor, which occupies the basal half of a forward directed head projection. This unusual compound eye consists of approximately 2500 ommatidia, which are arranged in such a way that the animal has almost circumferential vision, but cannot look ahead or behind. It is thought that the eye operates on light-guide principles, and that the crystalline cones are the major dioptric component. Ommatidia in anterior-posterior rows show a greater overlap of visual fields than dorso-ventrally arranged ommatidia. Cone layer and retinula are separated by a 4 µm thick screen-membrane, which contains tiny pigment granules of 0.15 µm diameter. Cells of unknown function and origin, containing unusual multitubular organelles, are regularly found near the proximal ends of the crystalline cone threads. The twisted rhabdoms measure 18–20 µm in diameter, and consist of microvilli 0.05 µm in width, which belong to five retinula cells and which show no trace of disintegration. The position of interommatidial screening pigment, the density of retinula cell vesicles and inclusions, and the narrowness of the perirhabdomal space all suggest that the eyes have been light-adapted at the time of fixation for electron microscopy. The retinula cell nuclei lie on the proximal side of the heavily pigmented basement membrane. A tapetum or basal retinula cells are not developed. It is concluded that the eye optimally combines acuity with sensitivity, and that for distance estimation parallax may be important.

AbstractT. caudatusreacts to light with a momentary locomotory arrest. Two frontal ( = median) eyes each 370 μam in diameter, and a cluster of three small lateral eyes on either side of the prosoma are present. Each frontal eye possesses a large biconvex lens that produces a clear image approx. 200 μm behind the inner surface of the lens. This is compatible with an optically homogeneous lens of 1.51 refractive index. The retina of the frontal eye is eversc, and groups of predominantly three retinula cells, held together by desmosomes, give rise to centrally fused rhabdoms up to 20 μm wide. A tapetum is not developed in the frontal eye, but screening pigment granules are present; these remain in a dark-adapted position even when the eyes are fixed in daylight between 0700 and 0800 hr. Lateral eyes strongly reflect light because of a well developed tapetum. Although distally, clusters of mostly three cells resemble similar groups found in the frontal eyes, the retina of the lateral eye is reticulated and inverted, i.e.the retinula cell nuclei lie in front of the rhabdom in the path of the light, Rhabdomeres develop through interdigitation of membranes of apposing cells, whereas in the frontal eye they are of intracellular, monocellular origin. In both types of eye, rhabdom microvilli with diameters smaller than 70 nm were not encountered. Usually, microvilli were of irregular shape and orientation, displaying a state of disassembly. Clear images are not formed by the lenses of the lateral eyes. Differences between lateral and frontal eyes, and the considerable overlap of visual fields between them, suggest separate roles for the two photoreceptors.

Specimens of Mysis relicta from Pojoviken Bay (Finland) were divided into two groups, one kept at 4°C, the other at 14°C, in total darkness. Immediately following a 1 h exposure to noon sunlight both 4°C and 14°C animals displayed strongly reduced visual sensitivities. In both groups pre-exposure levels were regained in about two days, but apparently along slightly different routes. Slopes of V/log I curves hardly changed throughout the time of observation in the 14°C material, suggesting an adaptation to brighter light levels without undue stress responses. In the 4°C animals, however, there appears to have been not only a longer initial delay before recovery commenced, but slopes of V/log I curves indicated that these animals had reacted with depression to the bright light and needed time to regain their pre-exposure value. The results suggest that recovery is a two-stage process in which biochemical reactions and structural phenomena interact. The results, when compared with similar observations on Lake Pääjärvi specimens, underline the view that different localities may have populations of Mysis relicta which differ from each other in photophysiological characteristics.

Specimens of Mysis relicta from Pojoviken Bay (Finland) were divided into two groups, one kept at 4?C, the other at 14?C, in total darkness. Immediately following a 1 h exposure to noon sunlight both 4?C and 14?C animals displayed strongly reduced visual sensitivities. In both groups pre-exposure levels were regained in about two days, but apparently along slightly different routes. Slopes of V/log I curves hardly changed throughout the time of observation in the 14?C material, suggesting an adaptation to brighter light levels without undue stress responses. In the 4?C animals, however, there appears to have been not only a longer initial delay before recovery commenced, but slopes of V/log I curves indicated that these animals had reacted with depression to the bright light and needed time to regain their pre-exposure value. The results suggest that recovery is a two-stage process in which biochemical reactions and structural phenomena interact. The results, when compared with similar observations on Lake P??j?rvi specimens, underline the view that different localities may have populations of Mysis relicta which differ from each other in photophysiological characteristics.Des sp?cimens de Mysis relicta provenant de la Baie de Pojoviken (Finlande) ont ?t? divis?s en 2 groupes et maintenus dans l'obscurit?, l'un ? une temp?rature de 4?C et l'autre ? 14?C. Apr?s 1 h d'exposition en pleine lumi?re, les 2 lots d'animaux ont montr? des sensibilit?s visuelles r?duites. Dans les 2 groupes, deux jours ont ?t? n?cessaires avant le retour ? l'?tat initial, mais apparemment selon des modalit?s l?g?rement diff?rentes. Les pentes des courbes de V (amplitude de r?ponse) en fonction du log I (intensit? du stimulus) changent ? peine en fonction du temps pour les animaux conserv?s ? 14?C sugg?rant une adaptation ? des niveaux sup?rieurs de lumi?re vive, sans r?ponses de stress excessif. Pour les animaux conserv?s ? 4?C, cependant, il appara?t un d?lai plus long avant le retour ? l'?tat initial, mais aussi les pentes des courbes de V en fonction du log I sont d?prim?es ? la lumi?re vive; le d?lai pour retrouver leur valeur (initiale) est long. Ces r?sultats pr?liminaires sugg?rent que le retour ? la normale est un processus en 2 ?tapes, dans lesquelles des r?actions biochimiques et des ph?nom?nes structuraux interagissent. Les r?sultats, apr?s comparaison avec des observations similaires r?alis?es ? partir d'?chantillons du lac P??j?rvi, soulignent le fait que diff?rentes localit?s peuvent avoir des populations de Mysis relicta qui diff?rent par leurs caract?ristiques photophysiolo-

The amphipod, Orchomene plebs, and the isopod, Glyptonotus antarcticus, both adapted to live in seawater of a temperature of-2° to 0° C, were kept for 7h at the unphysiologically high temperature of +10° C. Temperature elevation appeared to mimic light adaptation with regard to the position of the screening pigment granules within the visual cells, but not with respect to ultrastructural changes in the microvillar array of the rhabdom, i.e. the visual membranes. Cellular metabolism, membranous fatty acid composition, and ion fluxes, all known to be readily affected by an increase in temperature, are thought to be responsible for the observed effects. Pigment granules could possibly cause an elevation of intracellular temperatures due to the fact that they are dark and dissipate absorbed energy as heat.

Presumably, as a consequence of a 3-h exposure to light of 350-nm wavelength (1.5 × 1015 photons/cm2 sec) followed by a period of 20 h of rest in the dark, the four smaller retinula cells in each ommatidium of the eye of the butterfly Papilio xuthus contain a structure in the peripheral regions of their cytoplasm that resembles a portion of a rhabdom. Evidence for and against the view that this unusual, highly ordered arrangement of membranes represents a trophospongium is presented. In view of the fact that the structure in question only occurred at the same time when rhabdomeres were in a process of disintegration or reformation, the authors conclude that the structure in question is involved in the supply or removal of substances during a period of considerable activity of the retinula cell.

Based on observations and tests in the field, we conclude that during the day Petrolisthes elongatushas a considerably greater tendency to conceal itself at low rather than high tide. We provide evidence that vision is involved in detecting potential rock shelters. To small crabs (carapace lengths no more than 5 mm) a small rock close by, is apparently more attractive than a bigger one at greater distance subtending the same sector of arc. In large crabs (carapace length at least 15 mm) a tendency for the reverse was seen with bigger as well as smaller rocks close by being less attractive than similar shelters 1 m away. We believe that the greater desirability of more distant targets in larger crabs is related to their greater physical stamina and visual sensitivity to extended sources. This allows them to run away from a disturbance further than a small crab.

In specimens of Halicarcinus lacustriesof 6 mm body length and width, the two compound eyes each comprise about 400 ommatidia, and anatomically resemble those of other brachyuran crabs. All ommatidia are of the apposition type with short, proximally tapering, quadripartite crystalline cones as well as a cornea (maximum thickness 18 μm) with con vexly‐curved inner surfaces. The mean distance from cornea to basement membrane is 125 μm, and interommatidial angles average 9.5°. Each ommatidium possesses a horizontally‐banded rhabdom, 35–40 μm long and 2.5 μm wide, with seven contributing retinula cells. An eighth axon can be traced to a small distally‐placed retinula cell. We conclude that the photoreceptors of H. lacustrisare useful in detecting small environmental changes in brightness, as well as the plane of polarized light, but have poor spatial and temporal resolution. High densities of screening pigment granules throughout the eye, a decrease in microvillus diameter from an average of 61.1 nm distally to 51.4 nm proximally, and an abundance of tiny, spherical vesicles along the edge of the rhabdom, collectively indicate that the eyes of H. lacustrismay easily be damaged by excessive radiation. Therefore, despite the apposition anatomy of its eye, H. lacustrismust avoid sunny places if it is to perform optimally. The main roles of the eye are likely to involve predator detection, orientation, and synchronization of activities between individuals.

Abstract: Fifty randomly selected publications dealing with aspects of crustacean vision had theirMaterials and methods sections examined. In half of the articles gleaned, only the name of the animal under study was given; the other half mentioned “adult” or “mature” animals; twelve papers provided information on size or age of the experimental animal and six gave the sex. InPetrolisthes elongatus, rhabdom microvilli not only become more regular in outline as the animal grows, but also decrease in diameter from 90.4±21.2 nm in crabs of 5.0–8.9 mm carapace length via 86.6±13 nm in crabs of 9.0–12.9 mm carapace length to 79.7±7 nm in crabs of 13.0–16.9 mm carapace length. Approximately 400 cross sectional diameters of microvilli from identical regions in four eyes of each size class were measured and provided the basis for Anova-, Levene-, andt-tests. The three size classes possess microvilli of significantly different diameters and standard deviations. Our observations show that investigators of the crustacean photoreceptor have frequently neglected to consider the size of their experimental animals, but that this practice should not be continued as the now documented changes in microvillus diameters may influence the amount of visual pigment present and, thus, the photoreceptor's sensitivity to light.

Insects used as human food in three different ethnic groups of Papua and New Guinea are listed and compared with each other. It is concluded that a) entomophagy has developed in Papua and New Guinea independently from Australian and African influences; b) the number of species consumed is proportional to population density; and c) the hazards of malnutrition could be eased by further and more extensive use of insects as human food.

The first host record among Staphylinidae: Coleoptera, was established for an intracellular microsporidian, which was identified as a Nosematid. It lives preferentially in the accessory pigment cells and retinula cells of the compound eye of Creophilus erythrocephalus and differs from all forms described to date in possessing a coiled filament at the trophic amoeboid phase. An unidentified structure, possibly an intracellular parasite of plant origin, was found in one retinula cell.

The structures of the eyes of two Staphylinid beetles, one large (Creophilus erythrocephalus—18 mm in length) and one small (Sartallus signatus—3 mm in length), were compared.