In the
rainforests of Costa Rica, a
species of spider, known as Anelosimus octavius, sometimes displays a strange
but interesting habit. Periodically the spider would abandon their web and secrete a new
one, however it’s not for them. Rather it’s built for a ‘parasitic wasp’ that
was once living there. Ultimately the spider dies, but comes back from the dead
as a zombie… The parasitic wasp has ‘hijacked’ and taken control of the spiders
brain and the wasp’s larva comes from inside the spider’s body. Other organisms
that perform similar actions are: viruses, fungi, protozoans,
wasps, tapeworms and a ‘vast number of other parasites can control the brains
of their hosts and get them to do their bidding’. Recently scientists have
looked closer on sophisticated biochemistry that the parasites use. Co-editor
of the new issue, Shelley Adamo, of the Dalhousie University in Nova Scotia,
notes that: “the knowledge that parasites can manipulate their hosts is old.
The new part is how they do it, the last 5 to 10 years have really been
exciting” (Adamo). According to research on the Costa Rican spider, the new web
is perfect for the wasp and it’s plan. The spider’s old web was mostly of
threads where as the new web created has a platform topped by a thick sheet
that protects it from precipitation. With this in mind, the wasp larva crawls
to the edge of the platform and spins a cocoon that hangs down through an
opening that the spider has provided for the parasite. Humans need no worry of
this ‘zombie-parasite’ because it is only lethal to small moths and other
parasites.
* Information obtained at www.nytimes.com
* Pictures obtained at www.3quarksdaily.com & www.ruleofthedice.com
Figure 24.1
Figure 24.2
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