Which is the world's deadliest spider,
really?
7 November 2014, by Rick Vetter, The Conversation
A study in 2000, described 422 bites by Phoneutria
spiders (pictured above), mostly P. nigriventer and
P. keyserlingi in eastern coastal Brazil. Two
children were seriously ill as a result of the bites –
one died. However, more than 80% of the
remaining bite victims had mild or no symptoms.
Another frequently cited dangerous species is P.
fera, however, this spider lives in the Amazon, far
from the banana growing areas in Brazil – and most
of the people. And although Brazil produces large
quantities of the fruit, most are eaten domestically
so little exportation occurs.
Cute monster: Phoneutria spider. Credit: dejeuxx, CC
BY
It seems Ebola and terrorism may have lost their
scare factor. That is because journalists have once
again turned to arachnophobia. "Brazilian
Wandering spider found under a bunch of bananas
in Waitrose home delivery," said one newspaper
recently.
Then there is the fact that most of the bananas
shipped to North America originate from Central
America and northwestern South America, far from
areas containing large Phoneutria spiders. So
these spiders pose little threat outside of Brazil (but
there can be exceptional cases such as the one
reported in the British supermarket Waitrose).
Every few months, almost like clockwork, a media
hype about these arachnids surfaces in the press.
But we rarely find a balanced story about deadly
spiders. Just how toxic are they, really?
Trying to compare spider toxicities is like
comparing apples and doorknobs. There are
different levels of effects, some painful, others not
so much. Probably the most reasonable way to
compare would be to look at historic fatalities.
The most commonly reported group is the
wandering spiders of the genus Phoneutria. These Hadronyche sp. lurking about. Credit: Marshall Hedin, CC
BY-NC
are traditionally the darlings of the media banana
spider reports. Always listed as deadly but are they
really?
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Of all the spiders whose toxicity is currently known,
probably the most toxic are the funnel-web spiders Latrodectus mactans. Credit: primeval, CC BY-NC-SA
of Australia (of the genera Atrax and Hadronyche).
Their bites are lethal to small children within
minutes or hours and adults within 24 hours – but,
The media likes to stir up anxiety using toxic
having said this, there have been no Australian
spiders in attempts to attract an audience.
fatalities since anti-venom was developed.
However, for most of us, spiders are less of a threat
than driving.
Widow spiders of the genus Latrodectus cause a
fair bit of morbidity. However, death from widow
bite is pretty much a thing of the past as supportive This story is published courtesy of The
Conversation (under Creative Commonscare and anti-venom has provided tremendous
relief. One mitigating factor is that deaths during the Attribution/No derivatives).
early part of the 20th century may have been due to
bites that occurred in men in outhouses bitten on
Source: The Conversation
dangling genitalia where thin skin and heavy
vasculisation allowed for quick introduction of
venom. Indoor plumbing has minimised widow
bites.
"Brown recluse and related spiders of the genus
Loxosceles have a widespread reputation for
causing damage, but, like Phoneutria spiders, there
is a great deal of exaggeration. Most recluse bites
cause only minor problems. About 10% develop
significant skin necrosis but even so, loxoscelism
experts recommend these can be treated with
minimal intervention. Fewer than than 1% of
recluse bites become systemic, typically in children,
and can cause death in 12 to 30 hours. However,
dialysis and hydration can reverse the systemic
effects.
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APA citation: Which is the world's deadliest spider, really? (2014, November 7) retrieved 17 June 2017
from https://phys.org/news/2014-11-world-deadliest-spider.html
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