How are humans affected by widows?
By Chelsie Vandaveer
August 20, 2003
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There are five species of widow spiders (genus: Latrodectus) in America north of Mexico, a total of forty described species worldwide. For the most part, widow spiders are secretive and nocturnal and seldom bite unless physically contacted and feeling threatened.
All spiders are carnivorous and considered beneficial because they eat insects. The venom comes from modified salivary glands (poison sacs) and is injected by means of the sharp 'fangs' at the tips of the chelicerae. Spider toxin is a means to subdue prey. After subduing prey, spiders inject digestive enzymes into the body of their victim; many bundle their prey in silk and leave it hanging for later. ("Black Widow Spiders", Spiders of Kentucky)
Spiders lack mouth parts with which to chew. Digestion takes place outside of the spider. Everything inside the prey's exoskeleton is liquefied; the spider sucks up its meal. (And you thought Sigourney Weaver's "Alien" was horrifying!) Oddly, no one cares when this happens to a cockroach.
Widow spider venom contains the extremely potent alpha-latrotoxin which attacks the nerve cells. The toxin has three domains or specific activities on neurons. It binds to two types of receptors and inserts itself into cellular membranes creating ion channels. The toxin stimulates exocytosis, in this instance, the secretion of neurotransmitters. ("Evolutionary Homologs", Thomas B. Brody, 1996)
The neurons are getting a message to stimulate the muscles. The muscles are contracting in response to the message from the neurons. The over stimulated muscles become painfully rigid especially in the abdomen with a stifling sensation of 'tightness' in the chest. Additional symptoms may include profuse sweating, an increase in blood pressure and heartbeat, nausea, fever, and in rare instances, asphyxiation. It is seldom fatal only because the widow injects very tiny amounts of the venom.
Emedicine has additional information on widow spider bites by Jerry R. Balentine, DO, FACEP. To learn more about widow venom and medical treatment for widow spider bites, click on the link:
http://www.emedicinehealth.com/black_widow_spider_bite/article_em.htm
Series: | 1 | | 2 | | 3 |
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
Suggested Reading:
How does a flower spider change color? Renfield's Garden - November 26, 2003
Yellow Garden Spider (Argiope aurantia) Plant of the Week - September 11, 2006
Why is firefly courtship dangerous? Renfield's Garden - April 16, 2003
What was spiderwort? What's in a Name? - December 6, 2002
Why are these males small and fast? What's in a Name? - August 29, 2003
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