In order for any large social colony to function, members must perform several different types of jobs. For example, some group members might be responsible for gathering or preparing food whereas others might defend the nest. Honeybees sort their tasks by age with each individual progressing through a set schedule of jobs as she matures. However, in Stegodyphus colonies, all the spiders tend to be the same age. How do they decide which among them will be responsible for capturing prey and which for warding off trespassers?
One possibility is that the spiders divide up jobs by body size. That is, spiders that happen to be larger than their mates might gravitate to certain jobs. Another is that the spiders have individual preferences or personalities.
To test these possibilities, the scientists selected forty spiders out of each of sixteen different nests and painted them, possibly using a technique similar to this method of painting ants. You can see the lovely result below.
Color-coding spiders helps scientists study their personalities.
Photo: Lena Grinsted.
Because of these differences, the authors conclude that S. sarasinorum have some rudimentary personality traits, though it's not clear what causes the variation in behaviors. Interestingly, there were also colony-wide differences in how the entire spider communities reacted to stimuli. As S. sarasinorum colonies are highly inbred (siblings tend to remain in the same nest together after having consumed their mother), this could indicate a genetic component to spider personality.
Obviously, no one is suggesting that arachnologists begin administering the Myers-Briggs test to their little charges. However, these data do show that spiders do not react as automatons and that there are differences between individual spiders. Needless to say, this was a rather unexpected result. We don't tend to think of such creatures as individuals. This will definitely give me pause the next time I sweep out my house.
Obviously, no one is suggesting that arachnologists begin administering the Myers-Briggs test to their little charges. However, these data do show that spiders do not react as automatons and that there are differences between individual spiders. Needless to say, this was a rather unexpected result. We don't tend to think of such creatures as individuals. This will definitely give me pause the next time I sweep out my house.
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