A team led by Tunghai University Department of Life Science professor Tso I-min has discovered that spiders actually hunt more by night than during the day, and also uncovered new facts about spider defense mechanisms and uses for their silk.
Using a night-vision camera, the team observed that nocturnal orb-weaving spiders have bright spots on their abdomens that play a part in attracting their prey by night, Tso said. If the spots are covered up, insects do not fall into the spider’s trap. The spider then finds it difficult to capture enough food.
The research team also used colored paper to make different paper spiders of different colors, which they hung in the trees. They discovered that when spiders passed by a deep-colored fake spider, they would stop, while the brightly colored fake spiders were routinely attacked by wasps.
Tso emphasized that there is an interplay of the visual signals on a spider’s body for pulling in prey and hunting, and consequently it is the combination of a deep base color on the body plus the brightness of the spots that yields results in hunting.
More interesting, to avoid attracting enemies, these spiders can make a dummy to confuse them. The research team recorded spiders using the uneaten portions of the bodies of their prey to protect their own egg sacs, and then covering this armor with a layer of silk, binding it tightly to the web. The size and shape are related to the specific spider.
These measures get enemies to believe wrongly that the spider is in another place, and attack that spot instead, thus reducing the chance of the spider itself being discovered, as though the predator were blindfolded.
Tso said spider silk is light, tough and biodegradable, and has already been made into silk cloth. Right now, a joint research project is under way in cooperation with the U.S. using spider silk to produce bulletproof vests and parachutes, as well as fishing rods and tennis rackets. There are also hopes that spider silk might be usable for medical sutures and as an artificial tendon replacement.
Because the elasticity and strength of artificial spider silk cannot match up to the real article, Tso hopes to further reveal the secrets of the spiders’ natural environment and the mechanics they use to weave webs of various types, to facilitate the development of new materials in the future.
(This article originally appeared July 28 in The Liberty Times.)