Ontogenetic approach reveals how cognitive capability and motivation shape prey‐searching behavior in Pholcus phalangioides cellar spiders

Abstract

An important part of understanding the evolution of behavior is understanding how and why behavior develops and changes throughout ontogeny. Patterns of behavior are shaped by an animal's capabilities as well as its motivations, both of which are subject to selection. We ran an experiment to see how spiders' efforts to recover lost prey change with age and to determine the relative contributions of shifts in capability and motivation. We found that as spiders mature, they spend less time searching to recover lost prey, and they discriminate less between prey of different sizes. We also found that even the youngest, least experienced spiders are cognitively equipped to search for lost prey. Thus, predatory behavior in spiders fluctuated primarily with each age group's motivations to capture and consume prey, and did not seem to be hindered by behavioral or cognitive limitations at young ages.

Western black widow spiders (Latrodectus hesperus) remember prey capture location and size, but only alter behavior for prey caught at particular sites

“…A different kind of searching can occur in the absence of a “triggering” stimulus. This searching is prolonged and non‐directional (see below), with the spider walking around the web and pulling or plucking on web threads to gain vibrational information (e.g., Movie S1), and occurs whenever the layout of the web is changed in the spider's absence (so the spider seeks to re‐orient itself) (LeGuelte, 1969; Sergi et al, 2021), or when an item in the web is removed (so the spiders seeks to re‐acquire it) (Kilmer et al, 2018; Kilmer & Rodriguez, 2019; Opell, 2001; Rodríguez et al, 2013; Rodríguez et al, 2015; Rodríguez & Gamboa, 2000; Rodríguez & Gloudeman, 2011). Consequently, this searching indicates the presence of a memory about the aspect of the web that has been changed.…”

“…We used an assay of memory afforded by the natural history and behavior of web spiders (Kilmer et al, 2018; Kilmer & Rodriguez, 2019; LeGuelte, 1969; Rodríguez et al, 2013; Rodríguez et al, 2015; Rodríguez & Gamboa, 2000; Rodríguez & Gloudeman, 2011). Whenever a prey item is snared in a spider's web, the spider quickly approaches it, every once in a while briefly orientating by tugging on the web to correct its trajectory (Foelix, 2011).…”

“…Some remember the location in the web where they captured prey, and alter their webs to make them better able to capture prey in the web location where past prey captures have occurred (Nakata, 2012). Many web‐building spiders also remember the contents of their web, such as the presence of prey, the relative size of captured prey, and even the relative number of captured prey (Kilmer et al, 2018; Kilmer & Rodriguez, 2019; Rodríguez et al, 2013; Rodríguez et al, 2015; Rodríguez & Gamboa, 2000; Rodríguez & Gloudeman, 2011).…”