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Scientists Find Moustache Help Spider Lure Prey

spider

Image credit: Heteropoda venatoria with egg sac / Fritz Geller-Grimm via Wikimedia CC BY-SA 3.0

The brown huntsman spider, also known as Heteropoda venatoria in technical term, has a outstanding white stripe on its face, which is something similar to a moustache. At present, by shaving off such moustaches, scientists have found that the vibrant bristles help these spider lure flying insects to be their prey in the dark. This latest discovery was released in the recent issue of Animal Behaviour this April.

It is known that coloration is vital for animals in regard to visual communication, thus predators would apply visual signals like bright body to attract prey using, although this kind of technique is generally used by animals hunting in the daytime. Therefore, previous studies were not focused on nocturnal predators, because they concentrated on using bright body coloration to lure prey. It is actually unexpected that such tactic for foraging would happen in low lighting.

In order to better understand about the color-mediated prey attraction related to a nocturnal predator, I-Min Tso and his team from Tunghai University were engaged in field experiments on both dummies and real brown huntsman spiders. By application of infrared video cameras, I-Min Tso’s team had monitored the responses of nocturnal prey to normal spiders and spiders without white stripe, which were lightly shaved off under the anaesthetization.

The team, dealing with both dummy and real spiders, discovered that an intact white tache would greatly promote the attraction rate of nocturnal prey. Even at night, this outstanding moustache coloration served as a visual lure for flying insects just like moths. Reflecting light differently from the rest of the body, the bright coloring of white hair did appear to make flying insects confused. Talking of their discovery, Tso said, it was much likely that the moths had mistakenly observed the white coloration to be a nocturnal blooming flower in the period of their foraging at night.

As there are so many other examples of bright body coloration in the animal world, kingdom, the moustache could play a part in sexual selection. For the time being, the team is trying to find out whether the stripe is also linked with mate choice.

Journal reference: Zhang, Shichang, et al. “A nocturnal cursorial predator attracts flying prey with a visual lure.” Animal Behaviour 102 (2015): 119-125.

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