Jul

7

SpiderHere's an interesting BBC article about research on spider survival strategies.

Researchers hypothesized that a species of spider that decorates it's web with prey carcasses would benefit from a camouflage effect, but it turned out that these spiders actually received many more attacks from predators than those with undecorated webs. For these arachnids, unless the web decoration serves another purpose I imagine the trick worked for a good while before the predator-prey arms race escalated to the next level. Now that the other side seems to have the upper hand, I wonder for how long the spiders will continue to direct their energies pursuing a futile strategy. Other spiders are stepping up their game, for when the researchers tested the idea on another species of spider that decorates it's web with actual size replicas of itself, they found that that the decoy effect outweighed the increased risk of detection.


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  1. Orson Terrill on July 10, 2009 6:50 pm

    This sort of thing never fails to inspire.

    In all life, that I know of, reproduction rates and survival rates are inversely correlated. So if a plant/animal/insect of some kind has a high success rate from birth, they probably come in smaller numbers. Sea turtles are always a good illustration, as everyone has seen the footage of thousands of the newly hatched overwhelming their predators with numbers. It would be interesting to compare the reproduction rates of the Spider that is attacked more because it builds these decoys versus the one that is not (If it has a higher mortality rate, it must have a higher reproduction rate, or the thing is on its way out).
    (Are there trading operations where only a few traders are reproduced or is the business categorically “turn and burn”?)
    1) Wasps are not the only predator of spiders, so this spider may truly have a net decrease in predation, the researchers only counted wasp attacks?
    2) Gene diversity is important to non-social spiders (social spiders are inbred regularly, and have evolved for it), and if this spider were to maintain very high reproductive rates, depending on how their population per square meter increased without this predation, they could be prone to inbreeding and subsequent disease and infertility. Overtime the one that attracts more predators, but has a higher reproduction rate, could win out in this scenario (As the inbred creatures that suffer from the effects of inbreeding are smaller, take longer to develop, etc).
    3)Ecology never fails to amaze. It could be much more complicated than all explanations offered currently, or even as straightfoward as “they are losing the battle and the war”.

    I am not an expert on this but I had some time so I reported back.

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