Social aggregation of the marine isopodCirolana harfordidoes not rely on the availability of light‐reducing shelters

Abstract

Abstract. Social aggregation under shelters can afford benefits to animals such as protection from predators. Many isopods and insects are negatively phototactic and this may help them gravitate towards shelter. Previous studies show that, when placed in an arena with two red shelters, specimens of the marine isopod Cirolana harfordi and the terrestrial isopod Porcelio scaber pick one of the two shelters at random and aggregate under it, demonstrating social aggregation under light-reducing shelters. In the present study, an arena with two clear shelters was used to determine whether group sizes of 4, 8, 12 and 16 C. harfordi specimens display social aggregation when the shelters do not accommodate negative phototaxis. In all group sizes, C. harfordi specimens picked one of the shelters at random and significantly more animals aggregated under this shelter compared with the other. Cirolana harfordi also displayed aggregation in an arena with no shelters. Accordingly, C. harfordi specimens do not require shelters that reduce light to display social aggregation. The ability to locate suitable shelter under which there is no substantial reduction in light could benefit the animal in a natural environment comprising heavily shaded areas, as well as at night.

Behavioral Biomarker Responses of Filopaludina bengalensis to Acute Copper Toxicity

“…In general, intraspecific aggregation in animals ensues due to variety of reasons like food, shelter, parental care, protection etc. (Salma and Thomson 2018;Deyashi et al, 2019). Here, the aggregation response observed in different sets is thought to be a defensive technique to withstand the impact of the metal stressor (Deyashi et al, 2019).…”

Emergence and retention of a collective memory in cockroaches

“…The dynamics and the frequency of the different choices are affected by the stochasticity of the individual behaviour and the initial distribution of the population (initial conditions). In a constant environment, shelter selection in gregarious animals [ 19 , 20 ] usually leads the group to choose one shelter, which stays occupied over time (stable stationary state) despite some punctual perturbations or activities (e.g. periodical) [ 21 ].…”

“…From a theoretical point of view, collective memory is based on the nonlinear dynamics generated by social interactions that can in some cases lead to multistable patterns [ 44 ]. These properties have been shown to be present in gregarious species [ 19 , 45 , 46 ] such as the American cockroach [ 47 ]. In this context, a previous study [ 21 ] has shown the capacity of this insect to maintain a collective decision when faced to short environmental perturbations.…”