INTRODUCTION Sharks have successfully lived in marine ecosystems, often atop food chains as apex predators, for nearly one and a half billion years. Throughout this period they have benefitted from an immune system with the same fundamental components found in terrestrial vertebrates like man. Additionally, sharks have some rather extraordinary immune mechanisms which mammals lack. AREAS COVE...

A population of young blacktip sharks was monitored over three years to determine their mortality rates using a series of acoustic listening stations. Based on these data it was possible to use several mortality estimators, including indirect life -history based methods and direct methods such as the Kaplan-Meier and SURVIV methods, to estimate natural, fishing and total mortality. Kaplan-Meier...

Despite the ongoing need for shark conservation and management, prevailing negative sentiments marginalize these animals and legitimize permissive exploitation. These negative attitudes arise from an instinctive, yet exaggerated fear, which is validated and reinforced by disproportionate and sensationalistic news coverage of shark 'attacks' and by highlighting shark-on-human violence in popular...

Acoustic telemetry was used to identify the short-term horizontal and vertical movement patterns of the bigeye thresher shark Alopias superciliosus in the eastern tropical Pacific Ocean during the summer of 1996. Two immature female sharks, 175 and 124 cm PCL (precaudal length), were tracked for 96 and 70 h, respectively, demonstrating very distinct crepuscular vertical migrations similar to th...

Fishes with internalized and endothermic red muscles (i.e. tunas and lamnid sharks) are known for a stiff-bodied form of undulatory swimming, based on unique muscle-tendon architecture that limits lateral undulation to the tail region even though the red muscle is shifted anteriorly. A strong convergence between lamnid sharks and tunas in these features suggests that thunniform swimming might b...

The Greenland shark (Somniosus microcephalus), an iconic species of the Arctic Seas, grows slowly and reaches >500 centimeters (cm) in total length, suggesting a life span well beyond those of other vertebrates. Radiocarbon dating of eye lens nuclei from 28 female Greenland sharks (81 to 502 cm in total length) revealed a life span of at least 272 years. Only the smallest sharks (220 cm or less...

We describe a technique for measuring a Seebeck effect in gels and present data for three systems. Notably distinct signals are obtained for gel originating in the electrosensitive organs of marine sharks, synthetic collagen-based gel, and as a control, seawater, the gels' solvent. Only the gel of sharks shows a reversible thermoelectric signal. The difference between gel samples and seawater s...

The life history of the whale shark (Rhincodon typus), including its reproductive ecology, still remains largely unknown. Here, we present results from the first whale shark population study around Darwin Island, Galapagos Marine Reserve. Following a diversified approach we characterized seasonal occurrence, population structure and size, and described habitat use of whale sharks based on fine ...

The present study examined the feasibility of measuring the steroid hormone corticosterone in fecal extracts of epaulette sharks, Hemiscyllium ocellatum. Six immature, captive-raised epaulette sharks (four females and two males) were obtained from two different zoos and were maintained in a closed-system, 530-liter aquarium. After a one-month adaptation, fecal samples were collected daily from ...

Coral reef habitats in the Papahānaumokuākea Marine National Monument (PMNM) are characterized by abundant top-level predators such as sharks and jacks. The predator assemblage is dominated both numerically and in biomass by giant trevally (Caranx ignobilis) and Galapagos sharks (Carcharhinus galapagensis). A lower diversity of predatory teleosts, particularly groupers and snappers, distinguish...