The role of tactile interactions in flight responses in the Bronze Cory catfish (Corydoras aeneus)

Abstract

One of the primary functions of animal aggregations is defence against predators. Many social animals enjoy reduced predation risk as a result of grouping, and individuals within groups can benefit from information transferred by their group‐mates about a potential predator. We present evidence that a tactile interaction behaviour we term “nudging” substantially modified group responses to a potential threat in a highly social catfish, Corydoras aeneus. These catfish deployed nudges during flight responses, and these nudges were associated with a greater likelihood of group cohesion following a threat event. Increased nudging behaviour also resulted in longer flight responses, a potentially costly outcome in natural contexts. In addition, individuals that perceived the threat first were more likely to initiate nudges, implying that nudges could be used to alert group‐mates to the presence of a threat. Taken together, our results suggest that tactile communication plays an important role in mediating anti‐predator benefits from sociality in these fish.

Social dynamics obscure the effect of temperature on air breathing in Corydoras catfish

“…Behavioural observations were recorded using a remotely operated Panasonic 4K video camcorder (Panasonic HC-VX980EB-K) mounted above the arena. The recordings were taken from above as bronze corydoras are bottom dwelling and mainly shoal in two dimensions, so social behaviour can be accurately measured from this angle (Riley et al, 2019).…”

“…It is interesting that the air-breathing frequency of groups was also affected by social cohesion, in that the more cohesive the group the greater the air-breathing frequency. In bronze corydoras, individuals that are close to each other can better utilise social cues and may also perceive less risk because there are other individuals in their immediate vicinity (Riley et al, 2019). A more remote possibility could be that, if individuals are closer together, they may reduce the amount of oxygen available for others in the group (Nadler, Killen, McClure, Munday, & McCormick, 2016).…”

The development of tactile social interactions in Corydoras aeneus larvae

“…The development of communication in social species is of particular interest, as communication can be a driving factor of group coordination (Conradt & Roper, 2005). Adults of our study species, Corydoras aeneus (Bronze Cory catfish), utilize tactile interactions that seem to facilitate group coordination (Riley et al, 2019b) and mediate flight responses from a potential threat (Riley et al, 2019a). The usage of tactile interactions in Bronze Cory catfish is unusual, as tactile stimulation often triggers a stereotyped threat response in fish called a 'c-start' that is deployed involuntarily when an individual perceives an urgent potential threat (Kimmel et al, 1980).…”

“…We conducted two experiments to investigate the development of communication and sociality in larval Bronze Cory catfish. Our previous work on adult Bronze Cory catfish describes an unusual tactile interaction behaviour, which we termed nudges, that individuals use during coordinated movements (Riley et al, 2019b) and while coordinating a group flight response (Riley et al, 2019a). This behaviour has several advantages for the study of group coordination, as nudges are discrete, easily quantifiable, and directed interactions between individuals: for each nudge, we can identify the initiator (i.e., the individual whose approach resulted in physical contact) and the recipient of the interaction.…”

“…This behaviour has several advantages for the study of group coordination, as nudges are discrete, easily quantifiable, and directed interactions between individuals: for each nudge, we can identify the initiator (i.e., the individual whose approach resulted in physical contact) and the recipient of the interaction. This behaviour is associated with increased coordination, with higher rates of nudging when fish are coordinating with one another when compared to fish that are in close proximity but not coordinating their movements (Riley et al, 2019b). Wild fish were observed utilizing this behaviour in several small streams in the Madre de Dios locality of the Peruvian Amazon in 2011 and 2013, particularly when fleeing the observer (RJR, pers.…”