Earthworm individualities when facing a conflict between turn alternation and aversive learning

Abstract

An individual’s personality develops through a combination of experiences and parental inheritance. When faced with a conflict, will an individual take an innate behavior or a learned one? In such situations, individuality will manifest itself. Here, we focused on turn alternation behavior, which is a habitual tendency to turn in the direction opposite the preceding turn, in earthworms (Eisenia fetida) and examined how this behavior is affected by an aversive stimulus. Of 10 earthworms, 3 were affected by the stimulus. Turn alternation deteriorated in two worms, one of which showed anti-turn alternation behavior, whereas the remaining worm showed an enhanced tendency toward turn alternation. Earthworms have a relatively simple nervous system. This study opens the door to investigate the neuronal basis for individuality that emerges between nature and nurture.

Modulation of ecosystem services by animal personalities

“…In fact, one hectare of agricultural land can contain upward of 7 million earthworms, the activities of which can transfer 20-25 tons of topsoil to the surface each year (Sinha et al 2010). In addition to Darwin's garden experiments, Nakashima et al (2018) demonstrated that individual earthworms differ in their ability to learn and solve problems. These results suggest that individuals may vary in their ability to perform tasks effectively, such as creating burrows and burying organic material.…”

“…In addition to Darwin’s garden experiments, Nakashima et al . (2018) demonstrated that individual earthworms differ in their ability to learn and solve problems. These results suggest that individuals may vary in their ability to perform tasks effectively, such as creating burrows and burying organic material.…”

Superoxide-imbalance Pharmacologically Induced by Rotenone Triggers Behavioral, Neural, and Inflammatory Alterations in the Eisenia fetida Earthworm

“…For this reason, these animals are consistently used in ecotoxicity assays to determine soil quality [10]. Behavioral studies have also suggested that earthworm decision-making processes are complex and highly individualized, leading to the suggestion that earthworms would be a good model for studies of personality evolution [11].…”