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Large Eyes (large + eye)
Selected AbstractsBigger is better: implications of body size for flight ability under different light conditions and the evolution of alloethism in bumblebeesFUNCTIONAL ECOLOGY, Issue 6 2007A. KAPUSTJANSKIJ Summary 1In social insects, reproductive success and survival of the colony critically depend on the colony's ability to efficiently allocate workers to the various tasks which need to be performed. In bumblebees, workers show a large variation of body size within a colony. Large workers tend to leave the nest and forage for nectar and pollen, whereas small workers stay inside the nest and fulfill nest duties. It was speculated that size-related differences of the sensory system might contribute to alloethism found in bumblebee colonies. 2In the first part, we investigated how body size determines eye morphology. We measured several eye parameters of Bombus terrestris workers and drones. In both, workers and drones, larger individuals had larger eyes with larger facet diameters, more ommatidia and larger ocelli. At similar body size, drones exhibited larger eyes and ocelli compared to workers. Due to theoretical considerations, we predict that large individuals with large eyes should be better able to operate in illumination conditions of lower intensity than small individuals, since ommatidial sensitivity is proportional to the square of facet diameter. 3In the second part, we tested this prediction. In a behavioural experiment, we first caught bumblebees of various sizes in the field and then determined the lowest light intensity level at which they are just able to fly under controlled laboratory conditions. We tested workers of B. terrestris and B. pascuorum, and workers and drones of B. lapidarius. Large bumblebees were able to fly under lower light levels compared to small bees, with light intensity thresholds ranging from 1·1 to 5·5 lux. 4Our results indicate that the increased light sensitivity of the visual system of large bumblebees allows them to fly under poor light conditions, for example, very early in the morning or late at dusk. This is of potential benefit to the survival of a bumblebee colony since flowers that open early in the morning usually have accumulated a relatively high amount of nectar and pollen throughout the night, and large bumblebees can utilize these resources earlier than most other bees. Thus, our findings have important implications for the understanding of the functional significance and evolution of alloethism in bumblebee colonies. [source] The superior colliculus of the camel: a neuronal-specific nuclear protein (NeuN) and neuropeptide studyJOURNAL OF ANATOMY, Issue 2 2006E. P. K. Mensah-Brown Abstract In this study we examined the superior colliculus of the midbrain of the one-humped (dromedary) camel, Camelus dromedarius, using Nissl staining and anti-neuronal-specific nuclear protein (NeuN) immunohistochemistry for total neuronal population as well as for the enkephalins, somatostatin (SOM) and substance P (SP). It was found that, unlike in most mammals, the superior colliculus is much larger than the inferior colliculus. The superior colliculus is concerned with visual reflexes and the co-ordination of head, neck and eye movements, which are certainly of importance to this animal with large eyes, head and neck, and apparently good vision. The basic neuronal architecture and lamination of the superior colliculus are similar to that in other mammals. However, we describe for the first time an unusually large content of neurons in the superior colliculus with strong immunoreactivity for met-enkephalin, an endogenous opioid. We classified the majority of these neurons as small (perimeters of 40,50 µm), and localized diffusely throughout the superficial grey and stratum opticum. In addition, large pyramidal-like neurons with perimeters of 100 µm and above were present in the intermediate grey layer. Large unipolar cells were located immediately dorsal to the deep grey layer. By contrast, small neurons (perimeters of 40,50 µm) immunopositive to SOM and SP were located exclusively in the superficial grey layer. We propose that this system may be associated with a pain-inhibiting pathway that has been described from the periaqueductal grey matter, juxtaposing the deep layers of the superior colliculus, to the lower brainstem and spinal cord. Such pain inhibition could be important in relation to the camel's life in the harsh environment of its native deserts, often living in very high temperatures with no shade and a diet consisting largely of thorny branches. [source] Do Child Molesters Have Aberrant Perceptions of Adult Female Facial Attractiveness?,JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 3 2003David K. Marcus The multiple fitness model (Cunningham, 1986) suggests that attractive adult faces combine youthful neonate features with indications of sexual maturity. But a question can be raised whether the multiple fitness model applies to child molesters. In contrast to prior studies that examined child molesters' attraction to children, we examined child molesters' perceptions of adult women. Incarcerated child molesters (N= 68) rated the attractiveness of photographs of 24 adult women. Their ratings were compared with ratings made by 30 heterosexual college men. The 2 groups displayed remarkably similar judgments (r= .91). Child molesters were not more attracted to neonate features compared to other men, nor were they more repelled by maturity features. Like the college men, the child molesters were attracted to faces with large eyes and high cheekbones. Because the multiple fitness model applied to child molesters, differences between the sexual behavior of child molesters and other men do not seem to be attributable to differences in their perceptions of potential adult female partners' faces. [source] Comparative anatomy of the cheek muscles within the Centromochlinae subfamily (Ostariophysi, Siluriformes, Auchenipteridae)JOURNAL OF MORPHOLOGY, Issue 2 2006Luisa Maria Sarmento-Soares Abstract Glanidium melanopterum Miranda Ribeiro, a typical representative of the subfamily Centromochlinae (Siluriformes: Auchenipteridae), is herein described myologically and compared to other representative species within the group, Glanidium ribeiroi, G. leopardum, Tatia neivai, T. intermedia, T. creutzbergi, Centromochlus heckelii, and C. existimatus. The structure of seven pairs of striated cephalic muscles was compared anatomically: adductor mandibulae, levator arcus palatini, dilatator operculi, adductor arcus palatini, extensor tentaculi, retractor tentaculi, and levator operculi. We observed broad adductor mandibulae muscles in both Glanidium and Tatia, catfishes with depressed heads and smaller eyes. Similarities between muscles were observed: the presence of a large aponeurotic insertion for the levator arcus palatini muscle; an adductor arcus palatini muscle whose origin spread over the orbitosphenoid, pterosphenoid, and parasphenoid; and the extensor tentaculi muscle broadly attached to the autopalatine. There is no retractor tentaculi muscle in either the Glanidium or Tatia species. On the other hand, in Centromochlus, with forms having large eyes and the tallest head, the adductor mandibulae muscles are slim; there is a thin aponeurotic or muscular insertion for the levator arcus palatini muscle; the adductor arcus palatini muscle originates from a single osseous process, forming a keel on the parasphenoid; the extensor tentaculi muscle is loosely attached to the autopalatine, permitting exclusive rotating and sliding movements between this bone and the maxillary. The retractor tentaculi muscle is connected to the maxilla through a single tendon, so that both extensor and retractor tentaculi muscles contribute to a wide array of movements of the maxillary barbels. A discussion on the differences in autopalatine-maxillary movements among the analyzed groups is given. J. Morphol. © 2005 Wiley-Liss, Inc. [source] Morphology and metamorphosis of Eupsophus calcaratus tadpoles (anura: Leptodactylidae)JOURNAL OF MORPHOLOGY, Issue 2 2005M.F. Vera Candioti Abstract Eupsophus calcaratus, a leptodactyloid frog from the austral Andean forests of Argentina and Chile, has endotrophic, nidicolous tadpoles. We studied a metamorphic series from Stages 31 to 46 of Gosner's developmental table (1960). Other than the scarce pigmentation, proportionately large eyes, and massive developing hindlimbs, the remaining external characters are similar to those of generalized, exotrophic larvae. At the same time, internal morphology does not reveal any character state attributable to the endotrophic-nidicolous way of life; conversely, structures such as the hyobranchial skeleton and the mandibular cartilages are similar to those of exotrophic-macrophagous tadpoles. The metamorphic process is characterized by the delayed development of diverse structures (e.g., ethmoid region, palatoquadrate, and hyobranchial apparatus), and the retention of some larval characters (e.g., parietal fenestrae, overall absence of ossification) with the absence of development of some "juvenile" characters (e.g., adult otic process, several bones) in metamorphosed individuals. These heterochronic processes and truncation of larval development are related to a shorter larval life (when compared to other species of the austral Andean region) and to the small size at metamorphosis. J. Morphol. © 2005 Wiley-Liss, Inc. [source] | ||||||||||