Parental females of a nest-brooding cichlid improve and benefit from the protective value of young masquerading as snails

Maternal Care-Providing Cichlid Neolamprologus furcifer Selectively Focuses on High-Threat Carnivorous Intruders, Limiting Attention to Other Threats

Animals adjust their behaviors based on information from multiple sources; however, the brain can effectively process limited amounts of information. Therefore, attention is restricted to a small portion of environmental stimuli. When animals process multiple information inputs, focusing on information that is deemed important improves detection probability. However, selective focus limits attention to other stimuli and associated behavioral responses. In this study, we examined how Tanganyikan cichlid, Neolamprologus furcifer, mothers selectively attack intruder fishes depending on the threat level and presence or absence of offspring. Species composition is complicated in Lake Tanganyika, and fish density is exceedingly high. Thus, parents must focus on high-threat-level intruders according to their parental care stage. Compared to females without offspring, mothers preferentially attacked carnivorous fishes farther from the nest over closer scale-eating fishes. Moreover, the percentage of females with injuries from scale-eating fish was significantly higher in those caring for offspring than those without offspring, demonstrating the cost of limited attention. Our results show that females focus on the early detection of carnivorous fishes because these predators dart in from long distances to forage eggs, fry, and juveniles, but this selective focus limits the attention placed on low-level threats. This study is the first to document the cost of limited attention in parents guarding offspring.

Prey mistake masquerading predators for the innocuous items they resemble

Understanding how natural selection has shaped animals' visual appearance to aid predator avoidance and prey capture has been an ongoing challenge since the conception of evolutionary theory [1,2]. Masquerade - animals resembling inedible objects common in the local environment (e.g. twigs, leaves, stones) - is one of a handful of strategies that has been suggested to serve both protective and aggressive functions (i.e. to work for both prey and predators) [3]. There is now good evidence for protective masquerade: predators detect masquerading prey but ignore them because they mistake them for the inedible objects they resemble [4]. However, there is no direct evidence that predators can benefit from aggressive masquerade [3,5]. Here, I tested the idea that prey detect masquerading predators but mistake them for the innocuous items that they resemble, making them less wary and easier for predators to catch. Because prey can only mistake masquerading predators for the objects they resemble if they have previous experience of those items, I manipulated house crickets' (Acheta domesticus) experience with dead leaves, before placing them in tanks with dead-leaf-resembling Ghost mantises (Phyllocrania paradoxa). I found that mantises given crickets with experience of unmanipulated dead leaves caught crickets faster and after fewer attempts than mantises given crickets without experience of dead leaves, or crickets with experience of manipulated dead leaves that no longer resembled mantises. These findings demonstrate that predators can indeed benefit from aggressive masquerade.