AsianScientist (Aug. 4, 2017) – In a pair of studies published in Behavioral Ecology and Scientific Reports researchers have found that personality traits of spiders impacts their decision-making and hunting styles.
Spiders, like humans and many other animals, have distinct personalities. Studies have shown that when humans make decisions in a haste, they tend to make more mistakes. To investigate if the same holds true for spiders, a research team led by Associate Professor Li Daiqin from the National University of Singapore (NUS) conducted studies on Portia labiata, a species of jumping spider. P. labiata is known for its high cognitive ability and complicated foraging strategies, but its personality is unexplored.
The researchers first tested the aggressiveness of P. labiata spiders by observing their responses when they are touched by a small soft brush. Spiders that attacked the brush were deemed to be more aggressive than those who ran away from the brush.
After determining the personalities of the jumping spiders, researchers assessed how the spiders make decisions. In the experiments, the spiders were given the choice of selecting a large or a small preferred prey. The large prey is associated with being better in quality, but is more dangerous to attack. The small prey is of lower quality, but easier to attack. The researchers studied the time the spiders took to make their decision and the choices they made.
The results showed that spiders who are aggressive made decisions faster than their docile counterparts. In addition, the choices they made are as accurate as those made by the docile spiders. The findings, published in Behavioral Ecology, demonstrated that the personalities of the jumping spiders are related to their cognitive styles.
“The outcome is rather surprising, as our team had initially thought that spiders that make quick decisions are more likely to make the wrong choices, similar to humans. This new knowledge provides us with a better understanding of ecological processes like foraging and predator-prey interactions in the animal kingdom,” Li explained.
In the study published in Scientific Reports, the NUS research team examined the personalities and behavioural predictabilities of two species of jumping spiders. The spider-eating P. labiata jumping spider was selected as the predator, while the Cosmophasis umbratica jumping spider, which is common prey of P. labiata, was selected as the prey.
To test the aggressiveness of the predator, the researchers placed mirrors in front of the P. labiata spiders and observed their response to their images. Those that touched the mirror were deemed to be aggressive while those that kept far from the mirror were deemed to be docile. The researchers also assessed the boldness of the prey Cosmophasis umbratica by introducing a mock predator, made of putty and paper clips, into the container it resides, and observing the prey’s behaviour.
Each test was repeated five times to estimate the predictability of the spiders’ behaviours, and to provide personality and predictability profiles of all the individuals studied. To determine the predator and prey interactions, the researchers placed a single predator and a single prey together to record the foraging performance of the predator. The test was conducted on different pairings, and the results were statically analyzed.
“The results showed that aggressive predators fared better when catching a prey with unpredictable behaviour while docile predators performed much better when hunting a prey with predictable behaviour,” explained Ms. Chang Chia-chen, a PhD student from the NUS Department of Biological Sciences who is the first author of both studies.
To deepen their understanding on the personalities of spiders, Li and his team plan to conduct further studies to test the relation between the personality and the decision-making styles of spiders by giving spiders tasks of different levels of difficulty. The team will also be studying the gene profiles of spiders to identify the genes responsible for their personalities.
The article can be found at: Chang et al. (2017) Predator Personality and Prey Behavioral Predictability Jointly Determine Foraging Performance.
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Source: National University of Singapore.
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