White sharks exploit the sun during predatory approaches

There is no conclusive evidence of any nonhuman animal using the sun as part of its predation strategy. Here, we show that the world's largest predatory fish-the white shark (Carcharodon carcharias)-exploits the sun when approaching baits by positioning the sun directly behind them. On sunny days, sharks reversed their direction of approach along an east-west axis from morning to afternoon but had uniformly distributed approach directions during overcast conditions. These results show that white sharks have sufficient behavioral flexibility to exploit fluctuating environmental features when predating. This sun-tracking predation strategy has a number of potential functional roles, including improvement of prey detection, avoidance of retinal overstimulation, and predator concealment.

A new method for resolving uncertainty of energy requirements in large water breathers: The 'mega-flume' seagoing swim-tunnel respirometer

Body size is a key determinant of metabolic rate, but logistical constraints have led to a paucity of energetics measurements from large water-breathing animals. As a result, estimating energy requirements of large fish generally relies on extrapolation of metabolic rate from individuals of lower body mass using allometric relationships that are notoriously variable. Swim-tunnel respirometry is the 'gold standard' for measuring active metabolic rates in water-breathing animals, yet previous data are entirely derived from body masses <10 kg - at least one order of magnitude lower than the body masses of many top-order marine predators. Here, we describe the design and testing of a new method for measuring metabolic rates of large water-breathing animals: a c. 26 000 L seagoing 'mega-flume' swim-tunnel respirometer. We measured the swimming metabolic rate of a 2·1-m, 36-kg zebra shark Stegostoma fasciatum within this new mega-flume and compared the results to data we collected from other S. fasciatum (3·8-47·7 kg body mass) swimming in static respirometers and previously published measurements of active metabolic rate measurements from other shark species. The mega-flume performed well during initial tests, with intra- and interspecific comparisons suggesting accurate metabolic rate measurements can be obtained with this new tool. Inclusion of our data showed that the scaling exponent of active metabolic rate with mass for sharks ranging from 0·13 to 47·7 kg was 0·79; a similar value to previous estimates for resting metabolic rates in smaller fishes. We describe the operation and usefulness of this new method in the context of our current uncertainties surrounding energy requirements of large water-breathing animals. We also highlight the sensitivity of mass-extrapolated energetic estimates in large aquatic animals and discuss the consequences for predicting ecosystem impacts such as trophic cascades.

Reproduction and ageing of Australian holocephalans and white-fin swell shark

The holocephalans are a slow growing, long lived group with a conservative life history strategy and require similarly conservative fishery management strategies to ensure their sustainable exploitation. White-fin swell shark are relatively short lived, highly fecund and likely to be more capable of withstanding intensive fishing.

Peopling of the Northern Territory part 1: a white elephant in a white Australia? The Northern Territory, 1901-1920

As a result of negative net immigration during the 1890s depression, Australians at the time of Federation were preoccupied about the slow rate of growth of the population. The non-Aboriginal population at the end of 1904 was approximately three and three-quarter million. and the publication in March 1904 of the Report of the New South Wales Royal Commission on the Decline of the Birth Rate and the Mortality of Infants did nothing to allay these concerns. Despite the perceived need for more people. the desire for racial unity was paramount. The main goals of policy makers at the time were to preserve a 'white' and essentially British Australia and create an imperial bastion in the Southern Hemisphere.

Peopling of the Northern Territory part 2: the white elephant laid to rest? In the inter-war years

Over time, the Immigration Restriction Act of 1901 and its later amendments were remarkably successful in excluding 'coloured' immigrants from Australia.  It is clear, however, that although most Australians wanted to preserve the 'white' and British character of their nation, the argument that 'non-white' and non-British immigrants were more suited to the settlement of northern Australia was frequently debated in the early decades of the twentieth century.  While this idea continued to challenge the validity of a 'white Australia' in the north, public figures were divided on the issue.  This article examines in some detail the contemporary debates over the peopling of the Northern Territory in the inter-war years.

Black and white is always grey-the power of the police to conduct a strip search in Victoria

The performance of a strip search by a police officer is a serious interference with the liberty and dignity of an individual. However, it is considered by police to be an important part of their law enforcement armory and one that is increasingly necessary to utilise to assist in the investigation and prosecution of drug-related crimes. This article considers the troublesome issue of whether and in what circumstances the common law may extend to police the power to conduct a strip search. In addition, there is an examination of the statutes and regulations that purportedly give police in Victoria the power to strip search with particular attention given to ss 81 and 82 of the Drugs, Poisons and Controlled Substances Act 1981 (Vic).

The behavioural and demographic contexts of white bread consumption

The aim of this study was to examine the demographic, health habits and personal values associations of white bread use. A total of 474 randomly selected consumers completed a questionnaire about bread consumption, health habits and personal values. The findings showed that compared with non-consumers white bread users were younger, less educated, more likely to have children and to be smokers. They were less likely to follow vegetarian, low fat or special diets or use alternative therapies. Non-consumers were more likely to hold pro-nature universalistic values. This suggests that the use of this staple food is associated with demographic, behavioural and ideological domains. Their causal inter-relationships require further investigation.

Harnessing zebrafish for the study of white blood cell development and its perturbation

Considerable progress has been made in understanding the molecular basis of normal white blood cell development and its perturbation in disease through the use of clinical studies and traditional animal and cell line models. Despite this, however, many questions are still being answered and white blood cell disorders, including leukemia and lymphoma, remain a significant health problem. The zebrafish (Danio rerio) has emerged as a powerful alternative vertebrate model for the study of development and disease. We review the recent application of zebrafish to the study of white blood cell development and its disruption, particularly leukemogenesis. Such studies have highlighted the overall conservation of these processes throughout vertebrates, and establish zebrafish as a useful experimental model. This organism is now poised to make an important contribution to our understanding of the underlying genetic control of white blood cell development and its disruption, as well as the identification of new therapeutic agents.