Irrespective of size, scales, color or body shape, all fish are just fish: object categorization in the gray bamboo shark Chiloscyllium griseum

Object categorization is an important cognitive adaptation, quickly providing an animal with relevant and potentially life-saving information. It can be defined as the process whereby objects that are not the same, are nonetheless grouped together according to some defining feature(s) and responded to as if they were the same. In this way, knowledge about one object, behavior or situation can be extrapolated onto another without much cost and effort. Many vertebrates including humans, monkeys, birds and teleosts have been shown to be able to categorize, with abilities varying between species and tasks. This study assessed object categorization skills in the gray bamboo shark Chiloscyllium griseum. Sharks learned to distinguish between the two categories, 'fish' versus 'snail' independently of image features and image type, i.e., black and white drawings, photographs, comics or negative images. Transfer tests indicated that sharks predominantly focused on and categorized the positive stimulus, while disregarding the negative stimulus

The Hamburg Ocean-Atmosphere Parameters and Fluxes from Satellite Data (HOAPS): Climatological Atlas of Satellite-Derived Air-Sea Interaction Parameters over the World Oceans

The present atlas is based on the newly available data set known as the Hamburg Ocean At- mosphere Parameters and Fluxes from Satellite Data (HOAPS), for the global oceans. It pre- sents the basic fields of air-sea interaction parameters such as sea surface temperature, specific humidity at air and sea surface temperature, difference in humidity, Dalton number, wind speed and the air sea fluxes such as latent heat, sensible heat and longwave radiation. The atlas also provides the hydrological cycle parameters over the global oceans such as evaporation, precipitation and freshwater flux. The data set covers the period July 1987 to December 1998 and provides the mean monthly, seasonal and annual fields of different variables. It is intended to provide a climatological data base for scientists and students in the field of climatology, me- teorology, oceanography, and air-sea interaction. The document describes the various satellite sensors used and details the method by which the fluxes are derived from those satellite data. This printed atlas is accompanied by a CD-ROM containing the data of all individual monthly averages of the considered parameters as well as the figures and this text. Fields with higher temporal and spatial resolution are also freely available to interested users for non-commercial scientific research. For details of how to access the Fields see: http:// www.mpimet.mpg.de/Depts/Physik/HOAPS

Adaptation reveals sensory and decision components in the visual estimation of locomotion speed

Locomotion speed provides important social information about an individual’s fitness, mood and intent. Visual estimation of locomotion speed is a complex task for the visual system because viewing distance must be taken into account, and the estimate has to be calibrated by recent experience of typical speeds. Little is known about how locomotion speed judgements are made. Previous research indicates that the human visual system possesses neurons that respond specifically to moving human forms. This research used point-light walker (PLW) displays that are known to activate these cells, in order to investigate the process mediating locomotion speed judgements. The results of three adaptation experiments show that these judgements involve both a low-level sensory component and a high-level decision component. A simple theoretical scheme is proposed, in which neurons sensitive to image flicker rate (temporal frequency) provide a sensory speed code, and a benchmark ‘norm’ value of the speed code, based on prevailing locomotion speeds, is used to make decisions about objective speed. The output of a simple computational model of the scheme successfully captured variations in locomotion speed in the stimuli used in the experiments. The theory offers a biologically-motivated account of how locomotion speed can be visually estimated

Evidence for extensive population structure in the white-spotted eagle ray within the Indo-Pacific inferred from mitochondrial gene sequences

The white-spotted eagle ray Aetobatus narinari is a species complex that occurs circumglobally throughout warm-temperate waters. Aetobatus narinari is semi-pelagic and large (up to 300 cm disc width), suggesting high dispersal capabilities and gene flow on a wide spatial scale. Sequence data from two mitochondrial genes, cytochrome b (cytb) and NADH dehydrogenase subunit 4 (ND4), were used to determine the genetic variability within and among 18 sampling locations in the central Indo-Pacific biogeographical region. Populations in the Indo-Pacific were highly genetically structured with c. 70% of the total genetic variation found among three geographical regions (East China Sea, Southeast Asia and Australia). F(ST) was 0.64 for cytb and 0.53 for ND4, with (ST) values being even larger, that is, 0.78 for cytb and 0.65 for ND4. This high-level genetic partitioning provides strong evidence against extensive gene flow in A. narinari. The degree of genetic population structuring in the Indo-Pacific was similar to that found on a global scale. Global F(ST) was 0.63 for cytb and 0.57 for ND4, and global (ST) values were 0.94 for cytb and 0.82 for ND4. This suggests that the A. narinari complex may be more speciose than the two or three species proposed to date. Further sampling and genetic analyses are likely to uncover the 'evolutionarily significant' and 'management' units that are critical to determine the susceptibilities of individual populations to regional fishing pressures and to provide advice on management options. Network analyses showed a close genetic relationship between haplotypes from the central Indo-Pacific and South Africa, providing support for a proposed dispersal pathway from the possible centre of origin of the A. narinari species complex in the Indo-Pacific into the Atlantic Ocean