by Lauren Reynolds

Created on: May 23, 2008

Predators use a diverse array of strategies to capture prey. One strategy is the using a trap, such as spiders do. So the casual question presented for this article was: What causes specific prey-capture strategies in sympatric web-building spiders?

There were a few hypotheses presented: the first and second went hand in hand "There is a trade-off between long-retaining webs and attacking slowly vs. short-retaining webs and attacking rapidly." It was also hypothesized that the reaction times would be different between spider species and the size of the webs would effect the time it takes to catch the prey.

The experiment was located at a coffee plantation in southern Mexico. To test the hypotheses, there were four types of spiders used: the Arrowhead Spider (also known as the Triangle Orb weaver), the Banana Spider (the Golden Silk Orb weaver), the Orchard Spider, and the Common House Spider (also known as the American House Spider because it is found in North and South America). The Arrowhead Spider, Banana Spider, and the Orchard Spider all use orb or orb-like web designs while the Common House Spider uses a sheet design. The experimental prey consisted of flies, bees, ants, leafhoppers, and mosquitoes. To start off, spiders were removed from their webs and it was measured how long the different types of prey would be retained. Then, they measured the prey capture times and analyzed the reactions of the four spider species to only the flies. By choosing the flies, they were able to avoid the possibilities of the spiders not noticing smaller prey or being hesitant to approach the bees.

It was predicted that the prey-capture strategy for the spiders would be a mixture of all the hypotheses. It was expected that the spiders with webs retaining prey for only a short time would attack more quickly than spiders with webs retaining for longer periods. Also- the different spiders would react at different times and the larger webs would create a longer reaction time causing the spider to need a web that would retain prey longer.

After the testing, it was shown that the prey capture times for the flies were correlated to the prey retention times only among the orb webs while the sheet web seemed to follow no pattern at all. This was because the spider, the Common House Spider, was slow to capture its prey and the prey was easily able to escape due to the lack of sticky silk used for the web. Surprisingly the reaction times of the spiders did not differ between species and the distance between the center and point of prey impact influenced only the running time of the Arrowhead Spider who had the largest average web size of the spiders.

So it was concluded that, for orb weavers only, there is a trade-off between building a long-retaining web and initiating slow attacks, as seen through the Arrowhead Spider and Banana Spider, versus building a short-retaining web and initiating fast attacks, as we saw with the Orchard Spider.

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