Behavioural and physiological responses to low- and high-intensity locomotion in Chinese shrimp Fenneropenaeus chinensis

Isopod parasite influences prawn responsiveness and activity

Most bopyrid isopod parasites, which are crustaceans themselves, settle in the branchial chamber of decapod crustaceans and feed on host haemolymph. Here we report the results of an experiment on the common prawn Palaemon serratus and the parasite Bopyrus squillarum. Infected and uninfected prawns were stimulated with pokes of a plastic rod until an escape response was triggered; the number of pokes was recorded as an indicator of prawn responsiveness, whereas the time spent moving following stimulation was used as an indicator of prawn activity. Our results show that bopyrid infection affects both prawn responsiveness and activity, with infected prawns requiring more pokes to move, and moving for less time compared to uninfected prawns. In nature, such behavioural changes may impact defence mechanisms and survival of infected prawns. This could contribute to decreases in P. serratus abundance, thereby affecting the coastal ecosystems home to this species and the fisheries reliant on it, such as the Irish shrimp fishery.

Tail display is regulated by anaerobic metabolism in an Asian agamid lizard

Understanding the mechanism underlying signal variation is an important goal in the study of animal communication. Several potential causes have been proposed for signal variation, including environmental noise (e.g. wind, sound), energy limitation, and predation risk, among others, but the physiological control of many signals are often unclear. Here, we examined the correlation between tail display signal variation and energy metabolic activity using an Asian agamid lizard Phrynocephalus vlangalii. Individual tail display signals were observed in the field, and blood lactate concentration as well as 2 energy metabolic enzymes was assayed. Our results showed that average tail coil speed was positively associated with blood lactate concentration, while tail coil duration was negatively associated with LDH activity. We also found that average tail lash speed was positively associated with blood lactate concentration, suggesting that the tail display behavior of P. vlangalii was regulated by anaerobic metabolism. Furthermore, the correlation between tail display behavior and energy metabolism was not sex-dependent. Taken together, our research provides insight into the physiological mechanisms underlying tail display variation in lizards, and suggests that tail display variation likely transmits important information on individual body condition and resource holding potential.