Making a Bee-Line for Food with Octopamine

How do you find the newest, trendiest restaurants with the best food in your neighborhood (that is, of course, during non-pandemic times when restaurants are all open)? Well, one way that you may notice the new hip spot is to follow the crowds. If you wander by a spot filled with folks enjoying mouth-wateringly delicious food, you will likely be drawn to visit that restaurant yourself. But, how does your brain process these signals about food resources and quality? Tianfei Peng and two of his colleagues from the University of Mainz in Germany dug into this question by looking at the inner-workings of a slightly simpler brain – that of the stingless bee – to uncover the brain's role in social animal foraging.The trio suspected that the compound octopamine could play a role in how both individuals and social groups find food and perceive its value. Octopamine is a major player in the brain function of invertebrate animals, including many insects, equivalent to the fight-or-flight hormone noradrenaline in vertebrates, including human

Flies Walk the Line for Serotonin

In the grand scheme of the animal kingdom, insects are often overlooked for their impressive locomotor skills. They can walk forwards, backwards and even upside down, traversing challenging environments with relative ease. But how do insects achieve this coordination? Clare Howard (Columbia University) and colleagues teach us that the insect nervous system employs a multifaceted signalling network to optimize their speed, gait and reaction timing to gracefully navigate through life.Using the vinegar fly (Drosophila melanogaster), Howard and colleagues surveyed the fly nervous system to establish the sequence of signals involved in locomotion

Serotonin: Octopus Love Potion?

When you think about human social behaviour, what animals do you immediately think of as most similar to us? Apes, dolphins, wolves? Sure, these animals display incredibly complex social interactions, just like us. But Eric Edsinger from the Marine Biological Laboratory, USA, and Gül Dölen from Johns Hopkins University, USA, teach us in their latest study that we aren't actually all that different from our more distant cousin: the octopus. While octopuses typically hang out by themselves and fight when they come across each other, they let bygones be bygones during the mating season. Until now, we had no idea why octopuses suddenly set aside their aggressive tendencies during this ‘special’ time. Using a unique combination of molecular and behavioural studies, Edsinger and Dölen delved into the brain of the octopus to uncover the neurological mechanisms that regulate their social behaviour.<br/

Birds Ruffled by Big-City Lights

The blazing lights of Times Square in New York City may be impressive for tourists, yet this blindingly bright attraction can cause problems for urban wildlife. Artificial light at night, typical of cities and suburban areas around the globe, can cause problems for the animals that we share space with, although the impact on local wildlife is often disregarded. Given the current global COVID-19 pandemic, understanding how stressors, such as artificial nocturnal light, alter infectious disease transmission is now even more pressing. So, Daniel Becker and colleagues from Indiana University in the USA delved into this question, looking at how persistent artificial light at night alters immunity and infection risk in wild animal communities

The Role of Physiological Traits in Assortment Among and Within Fish Shoals

Individuals of gregarious species often group with conspecifics to which they are phenotypically similar. This among-group assortment has been studied for body size, sex and relatedness. However, the role of physiological traits has been largely overlooked. Here, we discuss mechanisms by which physiological traits—particularly those related to metabolism and locomotor performance—may result in phenotypic assortment not only among but also within animal groups. At the among-group level, varying combinations of passive assortment, active assortment, phenotypic plasticity and selective mortality may generate phenotypic differences among groups. Even within groups, however, individual variation in energy requirements, aerobic and anaerobic capacity, neurological lateralization and tolerance to environmental stressors are likely to produce differences in the spatial location of individuals or associations between group-mates with specific physiological phenotypes. Owing to the greater availability of empirical research, we focus on groups of fishes (i.e. shoals and schools). Increased knowledge of physiological mechanisms influencing among- and within-group assortment will enhance our understanding of fundamental concepts regarding optimal group size, predator avoidance, group cohesion, information transfer, life-history strategies and the evolutionary effects of group membership. In a broader perspective, predicting animal responses to environmental change will be impossible without a comprehensive understanding of the physiological basis of the formation and functioning of animal social groups

Social familiarity improves fast-start escape performance in schooling fish

Using social groups (i.e. schools) of the tropical damselfish Chromis viridis, we test how familiarity through repeated social interactions influences fast-start responses, the primary defensive behaviour in a range of taxa, including fish, sharks, and larval amphibians. We focus on reactivity through response latency and kinematic performance (i.e. agility and propulsion) following a simulated predator attack, while distinguishing between first and subsequent responders (direct response to stimulation versus response triggered by integrated direct and social stimulation, respectively). In familiar schools, first and subsequent responders exhibit shorter latency than unfamiliar individuals, demonstrating that familiarity increases reactivity to direct and, potentially, social stimulation. Further, familiarity modulates kinematic performance in subsequent responders, demonstrated by increased agility and propulsion. These findings demonstrate that the benefits of social recognition and memory may enhance individual fitness through greater survival of predator attacks

Role of Water Flow Regime in the Swimming Behaviour and Escape Performance of a Schooling Fish

Animals are exposed to variable and rapidly changing environmental flow conditions, such as wind in terrestrial habitats and currents in aquatic systems. For fishes, previous work suggests that individuals exhibit flow-induced changes in aerobic swimming performance. Yet, no one has examined whether similar plasticity is found in fast-start escape responses, which are modulated by anaerobic swimming performance, sensory stimuli and neural control. In this study, we used fish from wild schools of the tropical damselfish Chromis viridis from shallow reefs surrounding Lizard Island in the Great Barrier Reef, Australia. The flow regime at each site was measured to ascertain differences in mean water flow speed and its temporal variability. Swimming and escape behaviour in fish schools were video-recorded in a laminar-flow swim tunnel. Though each school\u27s swimming behaviour (i.e. alignment and cohesion) was not associated with local flow conditions, traits linked with fast-start performance (particularly turning rate and the distance travelled with the response) were significantly greater in individuals from high-flow habitats. This stronger performance may occur due to a number of mechanisms, such as an in situ training effect or greater selection pressure for faster performance phenotypes in areas with high flow speed

Effect of Habitat Characteristics on the Distribution and Abundance of Damselfish Within a Red Sea Reef

For coral reef fish with an obligate relationship to their habitat, like Pomacentrid damselfish, choosing a suitable home amongst the reef structure is key to survival. A surprisingly small number of studies have examined patterns in adult damselfish distributions compared to other ontogenetic phases. The aim of this study was to determine which reef and coral colony characteristics explained adult damselfish distribution patterns in a Red Sea reef. The characteristics investigated were reef type (continuous or patchy), coral species (seven species of Acropora), and coral morphology (coral size and branching density). The focal damselfish species were Dascyllus aruanus, D. marginatus, Chromis viridis, and C. flavaxilla. Occupancy (presence or absence of resident damselfish), group size and fish species richness were not significantly different between the seven Acropora species. However, within each coral species, damselfish were more likely to occupy larger coral colonies than smaller coral colonies. Occupancy rates were also higher in patchy reef habitats than in continuous sections of the reef, probably because average coral colony size was greater in patchy reef type. Fish group size increased significantly with coral colony volume and with larger branch spacing. Multi-species groups of fish commonly occurred and were increasingly likely with reduced branching density and increased coral size

Thermal acclimation of tropical coral reef fishes to global heat waves

As climate-driven heat waves become more frequent and intense, there is increasing urgency to understand how thermally sensitive species are responding. Acute heating events lasting days to months may elicit acclimation responses to improve performance and survival. However, the coordination of acclimation responses remains largely unknown for most stenothermal species. We documented the chronology of 18 metabolic and cardiorespiratory changes that occur in the gills, blood, spleen, and muscles when tropical coral reef fishes are thermally stressed (+3.0°C above ambient). Using representative coral reef fishes (Caesio cuning and Cheilodipterus quinquelineatus) separated by \u3e100 million years of evolution and with stark differences in major life-history characteristics (i.e. lifespan, habitat use, mobility, etc.), we show that exposure duration illicited coordinated responses in 13 tissue and organ systems over 5 weeks. The onset and duration of biomarker responses differed between species, with C. cuning – an active, mobile species – initiating acclimation responses to unavoidable thermal stress within the first week of heat exposure; conversely, C. quinquelineatus – a sessile, territorial species – exhibited comparatively reduced acclimation responses that were delayed through time. Seven biomarkers, including red muscle citrate synthase and lactate dehydrogenase activities, blood glucose and hemoglobin concentrations, spleen somatic index, and gill lamellar perimeter and width, proved critical in evaluating acclimation progression and completion, as these provided consistent evaluation of thermal responses across species