Background: The ability to remotely monitor the behavior of animals and their interactions with their environment has revolutionized how ecologists conduct studies. The creative use and placement of sensors on both biologging and biotelemetric platforms can greatly expand the amount of information that can be garnered from ecological studies.Results: Sophisticated transmitters and data loggers, which once were built by the biologists that used them, are available off the shelf from many commercial manufacturers. The ability to purchase a wide variety of electronic tags has allowed for a wider adoption of electronic tags across ecology, but has resulted in many biologists utilizing them with little understanding of how they function. The purpose of this review is to provide a reader-friendly description of the many sensors available to monitor the behavior, physiology, and environment of both terrestrial and aquatic animals. Our approach here is firstly to describe the electrical and mechanical principles behind each type of sensor and secondly to present one or two classic examples of how they have been used to provide insights into the biology of species from a diversity of taxa. Behavioral sensors that record the speed, acceleration, tilt angle, and direction of movement of an animal as well as its swimming depth or flight altitude will be described. Additional sensors are mentioned that detect feeding and spawning behavior as well as the proximity to conspecifics, prey, and predators. Physiological sensors will be described that monitor muscular, sensory, brain, gastric activity as well as body temperature, and sound production. Environmental sensors will be described that measure irradiance, dissolved oxygen, and magnetic field intensity. It is our hope that this review serves as springboard for biologists to develop innovative ways to learn more about their subjects using the myriad sensors that are available today, and the exciting new sensors to be developed in the future.

Mark-recapture techniques can be used to estimate white shark (Carcharodon carcharias) population abundance. These frameworks are based on assumptions that marks are conserved and animals are present at the sampling location over the entire duration of the study. Though these assumptions have been validated across short-time scales for white sharks, long-term studies of population trends are dependent on these assumptions being valid across longer periods. We use 22 years of photographic data from aggregation sites in central California to support the use of dorsal fin morphology as long-term individual identifiers. We identified five individuals over 16–22 years, which support the use of dorsal fins as long-time individual identifiers, illustrate strong yearly site fidelity to coastal aggregation sites across extended time periods (decades), and provide the first empirical validation of white shark longevity >22 years. These findings support the use of fin morphology in mark-recapture frameworks for white sharks.

In this review of the behavioural patterns of chondrichthyan fishes, we have strived to produce a comprehensive catalogue of events and states and develop standardized terminology. Hence, actions that are slightly different, will be pooled under inclusive titles. Those used by different investigators are included in quotations within the textual descriptions of the motor patterns. This standardized ethogram will ideally lead to an increase in inter-observer reliability, giving researchers more confidence when reading colleagues’ papers that report behaviours that appear similar to theirs despite being described for different species. The descriptions are presented under the following categories: (1) maintenance (2) courtship (3) filter feeding (4) scavenging (5) predation (6) sociality (7) aggression and (8) defence. The many actions are illustrated by line drawings and photographs in composite figures with an attempt to provide an example of each action for a chimaera, shark, and ray. The diversity of patterns is evident from this ethogram, consistent with observation that the brain-to-body mass ratios of cartilaginous fishes are greater than a third of the bird species and greater than those for some mammalian species. The major impetus for assembling this ethogram is to demonstrate the diversity of behaviours exhibited by members of the Chondrichthyes and to dispel the apocryphal belief that members of this taxon are ‘simple feeding machines’.