tag:theconversation.com,2011:/us/topics/redback-spiders-8175/articlesRedback spiders – The Conversation2016-03-09T02:02:49Ztag:theconversation.com,2011:article/555702016-03-09T02:02:49Z2016-03-09T02:02:49ZHidden housemates: the Australian redback spider<figure><img src="https://images.theconversation.com/files/114233/original/image-20160308-15341-1ggxrjh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Latrodectus hasseltii, the redback spider. </span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Latrodectus_hasseltii.jpg">Toby Hudson/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Australia is infamous for its <a href="http://www.australiangeographic.com.au/topics/wildlife/2013/03/australias-dangerous-animals-the-top-30/">deadly snakes, spiders and sea creatures</a>. One of the most notoriously dangerous is the redback spider, <em>Latrodectus hasselti</em>, which is similar to the widow spiders found in the United States and worldwide. </p>
<p>What makes these creatures so feared is a combination of their potent venom and their preference for living near people. </p>
<p>But are these spiders really as bad as they seem? And what should we be aware of to minimise the risks of living with these hidden housemates? </p>
<h2>How to recognise a redback</h2>
<p>The female redback is immediately recognisable by the prominent long red stripe on her back, for which they are so aptly named. Females of the species tend to be larger than the males, with a body length of about 1 cm compared to 3–4 mm for males. </p>
<p>Adult females are jet black (with a red stripe), whereas juvenile females are generally brown with white markings. Males are normally light brown with white markings, but lack the distinctive red stripe. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=432&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=432&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=432&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=543&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=543&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=543&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Female redback spider (<em>Latrodectus hasselti</em>).</span>
<span class="attribution"><span class="source">Laurence Grayson/Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>One unique feature of redbacks’ mating is “<a href="https://www.youtube.com/watch?v=fgqGAvG-BZ8">sexual cannibalism</a>”. During mating, not only does the female eat the male, but the male actually assists her in this process by flipping his body towards her so that he is closer to her mouthparts. Because the cannibalistic process is so slow, mating continues until the male succumbs to his injuries.</p>
<p>While it may seem counter-intuitive, this is thought to increase his chances of producing offspring by fertilising more eggs (mating is prolonged while the female is devouring the male). She is more likely to reject subsequent male attention. Males also can’t produce any more sperm. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/fgqGAvG-BZ8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Redback spiders are found throughout Australia. They live anywhere with an adequate food supply, shelter and a warm enough climate for breeding. For the most part nocturnal, they use a web to capture prey (generally insects, although they have been known to eat other spiders and even small reptiles and mammals). </p>
<p>They use their venom to kill their prey following capture. Of the hundreds of compounds in their venom, only a single toxin, alpha-latrotoxin, is responsible for deaths in humans and other vertebrates.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A redback spider with a small lizard captured in its web.</span>
<span class="attribution"><span class="source">Calistemon/Wikimedia Commons</span></span>
</figcaption>
</figure>
<h2>Interactions with humans</h2>
<p>No matter how deadly an animal is, if it never meets a human it can never kill one. </p>
<p>Unfortunately, this is not the case for redbacks. Existing in a range of habitats from forest to desert (originating in Western Australia), the redback spider quickly took advantage of man-made habitats created by European settlers from the late 18th century onwards. Redbacks had colonised urban areas by the early 1900s. </p>
<p>Insects, their natural prey, are drawn to lights and waste. This makes urban areas an ideal hunting ground for the spiders.</p>
<p>Modern-day redback spiders rely on humans. A quick glance at the distribution of redbacks in Australia reveals it correlates well with populated areas. The spiders are most often found in or around human homes, with only a small proportion located outside urban areas. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=532&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=532&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=532&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=669&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=669&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=669&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Distribution map of redback spider specimen records.</span>
<span class="attribution"><span class="source">Atlas of Living Australia</span></span>
</figcaption>
</figure>
<p>This attraction to man-made habitats has facilitated the redback’s spread to other countries through world trade and global shipping. </p>
<p>In fact, the redback was unintentionally introduced, and has since established local colonies, in places including <a href="http://www.nzherald.co.nz/rotorua-daily-post/news/article.cfm?c_id=1503438&objectid=11396295">New Zealand</a>, the <a href="http://gulfnews.com/news/uae/environment/redback-spiders-are-back-don-t-panic-urges-dubai-municipality-1.1155440">United Arab Emirates</a>, the <a href="http://www.mirror.co.uk/news/uk-news/deadly-spider-can-kill-one-4715326">United Kingdom</a> and <a href="http://news.xinhuanet.com/english/health/2012-12/26/c_132065195.htm">Japan</a>. </p>
<p>New Zealand quarantine authorities commonly intercept the spiders in steel or car shipments. Any unintentional introduction is of concern both for local people, who may be <a href="http://www.dailystar.co.uk/news/latest-news/395595/Redback-spider-bite-kills-dad-of-five-Ireland">unaware of the spider’s dangerous bite</a>, and for the preservation of insects on which the redback would not normally have an opportunity to prey. </p>
<h2>How dangerous are they?</h2>
<p>The majority of reported spider bites in Australia are attributed to redbacks, which are responsible for around 2,000 hospitalised bite cases each year. However, not a single death due to redback venom has been reported for 50 years, since the introduction of redback antivenom.</p>
<p>Redback spiders tend not to be aggressive unless their web is disturbed.
Sometimes they may just give a warning bite without injecting any venom if they feel threatened. </p>
<p>Therefore, not every bite will require a trip to the hospital or treatment with antivenom. In fact, antivenom is normally given only in cases in which the injected venom has caused severe illness. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bite from a Latrodectus spider.</span>
<span class="attribution"><span class="source">David~O/flickr</span></span>
</figcaption>
</figure>
<p>When the redback venom enters the body, it produces a range of effects collectively referred to as “<a href="https://en.wikipedia.org/wiki/Latrodectism">latrodectism</a>”. Typically this includes severe and escalating pain that emanates and progresses from the bite site, swelling and localised sweating. Nausea, vomiting, headaches, abdominal or chest pain, generalised sweating and increased blood pressure indicate a severe bite. Symptoms of latrodectism usually last for 24 to 48 hours, but can persist for weeks in some cases.</p>
<p>Nearly all instances are ascribed to the larger female spider. Both the juvenile and adult produce physical symptoms of similar severity. Bites from the smaller males are reported to give only mild, short-lived pain.</p>
<h2>What we can do to live safely with them</h2>
<p>Keeping in mind that redback spiders are not generally aggressive unless disturbed, following a few simple precautionary measures greatly reduces the risk of being bitten. </p>
<p>Webs are normally found in dark, dry, sheltered spaces. Be careful around buildings, under houses, in roofs and in sheds and garages. Always check first before reaching into your mailbox or other dark holes. </p>
<p>Check around children’s sandpits, toys and bicycles, inside helmets or any other equipment that gets left outside. Before use, always shake out any clothes, shoes, gloves or garden tools that have been left outside. </p>
<p>When gardening, wear gloves and shoes. Be careful when disposing of rubbish or litter piles. Inactive cars are also great places for redbacks to build webs. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=639&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=639&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=639&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=803&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=803&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=803&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A redback spider in a corner of a household deck.</span>
<span class="attribution"><span class="source">Charles Haynes/flickr</span></span>
</figcaption>
</figure>
<p>Be extra observant in warmer months, particularly in the late afternoon and evening, when the spiders are most active. Children should also be taught not to touch spiders. </p>
<p>If you find a redback or a redback egg sac and want to get rid of it, the easiest way is to squash it with something like a rolled-up newspaper, but only if you think it is safe to do so. Pesticides are not very effective in the long term unless used frequently, because redbacks will generally recolonise after treatment.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Female redback with egg sac and prey (a blowfly).</span>
<span class="attribution"><span class="source">Fir0002/Flagstaffotos</span></span>
</figcaption>
</figure>
<p>If you do get bitten, don’t panic. For healthy people, a redback bite is not an immediate emergency. It is advisable to have someone stay with you and observe you for a few hours, in case severe symptoms develop, so that they can get you to a hospital. </p>
<p>Doctors can then monitor your situation and, if necessary, administer the antivenom. People with serious medical conditions (particularly heart disease), pregnant women, children or the elderly are at a much greater risk of severe, and potentially fatal, effects or complications. They should be monitored at hospital. </p>
<p>In any situation, if in doubt, seek medical attention.</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/55570/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natalie J. Saez does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Be thankful you aren’t a male redback spider.Natalie J. Saez, Research officer, Institute for Molecular Bioscience, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/509632016-01-10T19:16:23Z2016-01-10T19:16:23ZAre Australian snakes the deadliest in the world? Not even close<figure><img src="https://images.theconversation.com/files/107486/original/image-20160107-14020-5z2o2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is Australia really the most lethal nation on earth when it comes down to it?</span> <span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Many Australians pride themselves on the belief that, of all the countries in the world, their snakes, spiders, jellyfish, centipedes, fish, ticks, bees and ants are the worst. And it’s easy to believe they’re right.</p>
<p>After all, there’s <a href="http://www.ncbi.nlm.nih.gov/pubmed/524395">a 37-year-old list</a> that says that 21 of the 25 most toxic snakes in the world are all from Australia. And aren’t funnel-web spiders, box jellyfish, stonefish and cone snails all dead-set killers? </p>
<p>But is Australia really the most lethal nation on earth when it comes down to it? Actually, no, it’s not. And the reason is simple. </p>
<h2>A matter of perspective</h2>
<p>It’s useless to measure how dangerous something is based solely on laboratory lethality tests. Venom toxicity and the number of mice killed with a snake’s average venom yield, for instance, are interesting only from an academic perspective. </p>
<p>If you happen to be one of <a href="https://en.wikipedia.org/wiki/Epidemiology_of_snakebites">around 100,000 people</a> who die of snake bites around the world in any given year, such facts are irrelevant. The same goes for just about any other venomous creature we might like to proudly declare as the planet’s most lethal. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/107332/original/image-20160105-28969-1l0pl0j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Eastern Brown Snake (<em>Pseudonaja textilis</em>) and its relatives cause most of the bites and fatalities in Australia.</span>
<span class="attribution"><span class="source">David Williams</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While Australia has spiders, jellyfish and other animals with lethal venom, the reality is that bites and deaths are rare. In other words, despite very toxic venoms, these creatures don’t bite enough people to cause major problems. Even when they do bite, it’s rare for snakes to inject venom (or “envenom”), less than 450 of 3,000 snakebite cases a year, for example. Death is even rarer (two to three cases a year). </p>
<p>Animals that cause the greatest burden of human suffering and death are the ones we need to be most worried about, and from that perspective, the most dangerous are not Australian. </p>
<p>Consider snakes, one of the most feared groups of venomous animals in the world. If we want to know which snakes are the most dangerous, we should consider the global, rather than individual impact. That view shows three groups of vipers that collectively span almost all of the tropical developing world – and have a huge impact on human health – best deserve the title of <em>the world’s most dangerous</em>.</p>
<h2>Meet the carpet viper</h2>
<p>Perhaps the most dangerous of these three genera is a diverse group of small, seemingly innocuous vipers that range from Sri Lanka and India, across the Middle East and through a huge part of the northern half of Africa. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/105364/original/image-20151211-8297-39c4q6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">West African carpet viper (<em>Echis ocellatus</em>) from Togo – member of a genus of small vipers that are the world’s most dangerous snakes.</span>
<span class="attribution"><span class="source">David Williams</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>These snakes got their name from the patterns that adorn their bodies. They are small- to medium-sized vipers believed to injure and kill more people each year than any other species in the world. Yet they don’t make the list of most toxic snakes mentioned above at all. </p>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/22851309">In just one hospital</a> in Nigeria’s north-eastern Gombe State, 5,367 victims of carpet viper envenoming were treated over a two-year period. But for the use of an effective antivenom, the fatality rate may have been as high as 35% to 45%. That’s more cases at one hospital in two years than all the recorded cases throughout Australia in ten. </p>
<p>Their huge range across a vast swathe of the rural tropics brings carpet vipers into contact with hundreds of thousands of people each year. And while nobody has a tally of just how many lives they affect, international experts all agree that when it comes to the most dangerous snake, these vipers have no competition. </p>
<h2>Russell’s viper</h2>
<p>In Pakistan, India and Sri Lanka, carpet vipers give way to the larger Russell’s viper (<em>Daboia russelii</em>). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/105363/original/image-20151211-8314-1qqw4l0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Russell’s viper (<em>Daboia russelii</em>) arguably the most dangerous snake in Asia with a potent cocktail of destructive toxins in its venom.</span>
<span class="attribution"><span class="source">David Williams</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This pugnacious viper lurks in fields, rice paddies and farmland from Pakistan through India, Nepal, Sri Lanka, Bangladesh, Myanmar, Thailand and Cambodia, as well as Taiwan and southern China. There’s a distinct, disjoined population of an equally dangerous sister species (<em>Daboia siamensis</em>) in eastern Java and the lesser Sundas in Indonesia.</p>
<p>Like the victims of carpet vipers, those bitten by these snakes bleed uncontrollably and often fatally. At the same time, local tissue destruction and necrosis, acute kidney injury, neurotoxic paralysis, shock, and cardiac arrhythmia can produce a terrifying clinical picture that can very quickly lead to death. </p>
<h2>Lancehead pit vipers</h2>
<p>Latin America, from Mexico to Argentina, is home to more than 40 species in the genus <em>Bothrops</em>, lancehead pit vipers. Collectively, this very diverse group is responsible for many of the estimated 150,000 or more cases of venomous snakebites in Central and South America each year. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/105369/original/image-20151211-8329-fhie1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Venezuelan lancehead (<em>Bothrops venezuelensis</em>) one of a large, widely distributed genus of dangerous pit vipers that cause enormous misery in Latin America.</span>
<span class="attribution"><span class="source">David Williams</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Lancehead bites produce devastating local tissue injury with oedema (or fluid retention), bruising, skin and muscle necrosis and fluid-filled blisters. Permanent disability including amputation is common. </p>
<p>Systemic effects involving stopping the ability of blood to clot, platelet destruction, shock, acute kidney injury and thrombosis present doctors with a complex medical emergency that – even with the best care available in a modern hospital – can still ultimately prove fatal. </p>
<p>Since many cases occur in rural areas, away from good medical care, poor outcomes are common.</p>
<p>Within Australia, the low mortality from snakebite (and other types of venomous injury) is very much the product of decades of research and excellent clinical care, not to mention safe and effective antivenoms. </p>
<p>It’s the lack of these same attributes elsewhere in the world that renders snakebites such a potentially life-changing (if not, life-ending) public health issue. </p>
<p><em>This article is part of our series <a href="https://theconversation.com/au/topics/deadly-australia">Deadly Australia</a>. Stay tuned for more pieces on the topic in the coming days.</em></p>
<hr>
<p><em>David will be on hand for an Author Q&A between 11am and noon AEDT on Tuesday, January 12, 2016. Post your questions in the comments section below.</em></p><img src="https://counter.theconversation.com/content/50963/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Williams receives funding from CSL Limited, the National Health and Medical Research Council and the government of Papua New Guinea. He is affiliated with the Global Snakebite Initiative Limited, a not-for-profit advocacy organization, and is an employee of the University of Melbourne. </span></em></p>There’s a simple reason why Australia isn’t the most lethal nation in the world.David Williams, Head, Charles Campbell Toxinology Centre at the University of Papua New Guinea & Australian Venom Research Unit, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/510482016-01-10T19:15:54Z2016-01-10T19:15:54ZSpiders are a treasure trove of scientific wonder<figure><img src="https://images.theconversation.com/files/107496/original/image-20160107-13986-17lmrv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As a generalist predator, spiders, like this Western Rough Wolf Spider, help limit the number of insects in your garden.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/jean_hort/4521389919/">Jean and Fred/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Australia has an incredible diversity of native spiders, including the <a href="https://theconversation.com/health-check-what-should-you-do-if-youre-bitten-by-a-spider-49232">potentially lethal</a> funnel-web, the ubiquitous huntsman, and the charming peacock spider. Only two can be deadly for humans – the funnel-web and redback spiders – and we have antivenom for both.</p>
<p>Found all across the country, spiders play an important role in the environment as generalist predators. Increasingly, their venom is being used <a href="http://www.tandfonline.com/doi/abs/10.1517/14712598.2011.621940#.Vl4bD2QrIsk">to develop novel human therapeutics</a> and <a href="http://www.mdpi.com/2072-6651/4/3/191">to create new, selective, sustainable insecticides</a>.</p>
<h2>A model citizen</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1031&fit=crop&dpr=1 600w, https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1031&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1031&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1296&fit=crop&dpr=1 754w, https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1296&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/107499/original/image-20160107-13988-emlng8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1296&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How house spider webs change when the spider is exposed to different chemicals.</span>
</figcaption>
</figure>
<p>Spiders are often a starting point for children to fall in love with the natural world: they’re found almost everywhere, and everyone can appreciate their tremendous diversity. What’s more, scientists are constantly learning new things from them.</p>
<p>They’re an important model system to help us understand the basics of biology. We know that the spider and its web are so closely tied that exposure to different chemicals has <a href="http://ntrs.nasa.gov/search.jsp?R=19950065352">specific effects on how the webs are spun</a>. </p>
<p>Other research suggests the blue colour in tarantulas evolved independently <a href="http://advances.sciencemag.org/content/1/10/e1500709.full">at least eight times</a>. This may help inform our understanding of the evolution of colouration, as well as how to make better paints.</p>
<p>The peacock spider <a href="http://rspb.royalsocietypublishing.org/content/282/1820/20152222">has helped show</a> that strong sexual selection by females depends on a variety of factors. Scientists think <a href="http://www.nature.com/scitable/knowledge/library/sexual-selection-13255240">sexual selection</a> has had an impact on the striking coloration and complex signalling of this spider species, but this is the first evidence to definitively demonstrate female preference has played a role.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OOmUBuaMjzw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Dance, dance revolution.</span></figcaption>
</figure>
<h2>With great power…</h2>
<p>As a generalist predator, <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev.ento.47.091201.145240">spiders help limit</a> the number of insects in your garden. Although they’ll probably eat some good bugs as well as bad while they’re at it.</p>
<p>Spider venom is a complex chemical cocktail of hundreds of different components, and each type has its own very specific activity. Many individual venom components act on the insect nervous system and these can be very useful for scientific research. </p>
<p>My work, for instance, is on discovering newenvironmentally friendly <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0073136">insecticides from spider venoms</a>. Since insect nervous systems are very different from the one found in vertebrates (including humans), individual toxins are frequently active in insects but not in vertebrates, and vice versa. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/106386/original/image-20151216-30079-44o3x0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Chemistry of Spider Venom.</span>
<span class="attribution"><a class="source" href="http://www.compoundchem.com/2015/05/21/spider-venom/">Compound Interest</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>When we look for good insecticidal candidates <a href="http://www.ncbi.nlm.nih.gov/pubmed/10881200">we screen for</a> compounds with specific activity in insects and the absence of activity in vertebrates. It’s that specificity that makes spider venoms such powerful sources of new, sustainable insecticides, as well as excellent therapeutics.</p>
<h2>What’s in a venom?</h2>
<p>Spider venoms generally consist of three types of components: small components (salts, carbohydrates, amines and acids to name a few); peptides (small proteins that are generally highly structured); and enzymes (used for digesting food).</p>
<p>If you <a href="https://theconversation.com/health-check-what-should-you-do-if-youre-bitten-by-a-spider-49232">get bitten by a spider</a>, do your best to remain calm, and proceed directly to a medical professional so your symptoms can be monitored and treated. They will administer the appropriate antivenom if required.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=577&fit=crop&dpr=1 600w, https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=577&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=577&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=725&fit=crop&dpr=1 754w, https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=725&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/106207/original/image-20151216-25600-14x8czz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=725&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">The Conversation</span></span>
</figcaption>
</figure>
<p>Spiders deliver venom by injection, using mouth parts called <a href="https://en.wikipedia.org/wiki/Chelicerae">chelicerae</a>, which are informally known as fangs. The chelicerae are found on the front body segment, the cephalothorax, and that’s also where its eight legs are attached. </p>
<p>The abdomen is the other spider body segment, and that’s where the spinnerets, used to weave the web, are found.</p>
<p>Spiders sometimes appear hairy, but those are actually <a href="https://en.wikipedia.org/wiki/Seta">sensory setae</a> that are used to collect detailed information about the nearby environment. Depending on the spider species that could include temperature, humidity, and wind direction, and chemical information, such as the source of pheromones used in mating.</p>
<p>So leave your fear behind and go ahead, embrace the majesty of spiders. But pick your species carefully – <a href="http://www.abc.net.au/news/2015-11-27/police-respond-to-domestic-after-man-screams-over-spider/6979724">and try not to get the police involved</a>.</p>
<p><em>This article is part of our series <a href="https://theconversation.com/au/topics/deadly-australia">Deadly Australia</a>. Stay tuned for more pieces on the topic in the coming days.</em></p><img src="https://counter.theconversation.com/content/51048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maggie Hardy receives funding from The University of Queensland and UniQuest Pty Ltd.</span></em></p>Only two Australian spiders can kill you, but the rest are a pretty fascinating bunch.Maggie Hardy, Postdoctoral Research Fellow, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/492322015-10-26T05:11:52Z2015-10-26T05:11:52ZHealth Check: what should you do if you’re bitten by a spider?<figure><img src="https://images.theconversation.com/files/98720/original/image-20151017-25138-1uavcra.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Spiders such as this funnel-web (Hadronyche infensa) will only bite if threatened.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p><em>This article is about spider bites in Australia, but doesn’t constitute medical advice. Always see a medical professional if you believe you’ve been bitten or stung by a venomous animal.</em></p>
<p>I work with spiders for a living, and I’ve never been bitten by one.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=628&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=628&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=628&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=789&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=789&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98730/original/image-20151017-25117-zzxdt9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=789&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author milking a tarantula.</span>
<span class="attribution"><span class="source">@DrMaggieHardy/author provided</span></span>
</figcaption>
</figure>
<p>There are <a href="http://www.wsc.nmbe.ch/">more than 45,000 species of spiders</a>, but only a handful are potentially dangerous to humans. </p>
<p>Only two spiders in Australia are of medical concern: funnel-web spiders (in the family Hexathelidae) and redback spiders (<em>Latrodectus</em>, in the family Theridiidae). </p>
<p>A <a href="https://www.mja.com.au/journal/2003/179/4/white-tail-spider-bite-prospective-study-130-definite-bites-lampona-species?0=ip_login_no_cache%3D71b017124538a7aa5b6e5b2ea8f157c4">review of 130 confirmed white-tail spider bites</a> showed no cases of flesh-eating ulcers or confirmed infections, so those spiders are not considered dangerous to humans.</p>
<p>Most “spider bites” that doctors see are <a href="http://www.sciencedirect.com/science/article/pii/S0736467909007926">actually skin and soft tissue infections</a>. </p>
<p>The myth that spider bites cause secondary infection <a href="http://www.sciencedirect.com/science/article/pii/S004101011400600X">has also been busted</a>, although – as for any wound – disinfecting and cleaning is necessary. </p>
<p>In the course of your life you’ll see many spiders (and there are <a href="http://www.burkemuseum.org/spidermyth/myths/3feet.html">many more</a> you won’t see), but only if they feel threatened will they bite you. Generally a spider tries to warn you, but unfortunately you might not always see (or hear) the spider.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/NlIRJRm64GA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Please, do not do this to your pet tarantula. Most spiders don’t want to bite you.</span></figcaption>
</figure>
<p>Venoms are energetically expensive for the animal to make, and the spider <a href="http://www.sciencedirect.com/science/article/pii/S0041010112008173">doesn’t want to waste venom</a> if it’s not needed for defence or to catch its food. </p>
<p>Funnel-web spider venom is one of the few that is lethal to humans (and other primates). It’s deadly because of a single component (<a href="http://www.arachnoserver.org/toxincard.html?id=307">δ‑hexatoxin‑Hv1a</a>) out of the hundreds of different molecules in the venom.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98733/original/image-20151017-25125-1obmenw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The three-dimensional structure of the vertebrate-active toxin from funnel-web spider venom. The red lines indicate the molecular bonds that confer extreme stability to the peptide.</span>
<span class="attribution"><span class="source">@DrMaggieHardy using PDB structure/author provided</span></span>
</figcaption>
</figure>
<p>Redback spiders are the most commonly encountered spider of medical concern, but <a href="http://www.toxinology.com/generic_static_files/cslavh_antivenom_redback.html">less than 20% of all bites</a> cause significant medical symptoms. While unpleasant, the symptoms (which may include muscle pain, vomiting and sweating within 12 to 24 hours) are generally <a href="http://www.sciencedirect.com/science/article/pii/S0140673610622301">not lethal</a>. </p>
<p>Bites from funnel-web spiders are also rare and, again, the amount of venom injected is not always enough to cause significant medical symptoms. </p>
<p>After the antivenom was created in the early 1980s, recovery from nonfatal bites changed from several weeks to <a href="http://www.ncbi.nlm.nih.gov/pubmed/6503783?dopt=Abstract">one to three days</a>, and no one has died since. </p>
<p>Symptoms of exposure to a lethal dose of funnel-web spider venom include tingling around the lips, tongue twitching, salivation and muscle spasms, which may lead to convulsions. Subsequent high blood pressure, rapid heartbeat and respiratory distress are why the venom is potentially lethal. </p>
<p>When a funnel-web injects a lethal amount of venom, without the antivenom, <a href="http://www.toxinology.com/generic_static_files/cslavh_antivenom_funweb.html">death can occur within an hour</a>. </p>
<h2>Know your spiders</h2>
<p>Tarantulas can climb glass and plastic; funnel-web spiders cannot. Funnel-web spiders have a classic strike pose to threaten off predators, in which they rear up on their back legs.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/a-dGVqqN6i8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The author, milking a funnel-web spider. This spider is being handled by an expert for research purposes; do not try this at home.</span></figcaption>
</figure>
<p>Despite the distinctive look of a funnel-web spider, a number of spiders look similar. Male and female funnel-web spiders are large (on average body length of one to five centimetres), with a brown or black body. The front of the body is glossy and may be covered in some dark hairs; the spinnerets at the back of the abdomen are easily visible. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=441&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=441&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=441&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=554&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=554&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98731/original/image-20151017-25112-10blplx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=554&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">All these spiders are potentially dangerous, but only two are funnel-web spiders. Clockwise from top left: male Sydney funnel-web spider (<em>Atrax robustus</em>); male mouse spider (<em>Missulena bradleyi</em>); female mouse spider (<em>Missulena</em> spp), and female Blue Mountains funnel-web spider (<em>Hadronyche versuta</em>).</span>
<span class="attribution"><span class="source">Photos from the Australian Museum.</span></span>
</figcaption>
</figure>
<p>Redback spiders are small (1cm for females, 0.4cm for males), and are black or sometimes brownish in colour. Females have an obvious orange or red stripe (which may be vaguely hourglass) on the underside of the abdomen. Males have similar, but less distinct, markings.</p>
<h2>Step 1: Don’t panic</h2>
<p>If a spider bites you, keep a cool head. Treat each bite as though it could be deadly, since it takes an expert to tell a funnel-web spider from any of the other large, black spiders found in Australia. </p>
<p>See a medical professional immediately if you think you may have been bitten.</p>
<p>For funnel-web and mouse spider bites, experts <a href="http://www.sciencedirect.com/science/article/pii/S0041010199001713">recommend</a> using a <a href="https://en.wikipedia.org/wiki/Pressure_immobilisation_technique">pressure-immobilisation bandage</a> before seeking medical help, to slow the progress of venom into your circulatory system and around the body. </p>
<p>Proceed immediately to a medical professional who can monitor your symptoms and determine whether the antivenom is required (most hospitals stock it).</p>
<p>There is no proven first aid treatment for redback spider bites. However, according to Associate Professor Julian White, a clinical spider bite expert at the Women’s and Children’s Hospital in North Adelaide, the immobilisation method is not appropriate for redback spider bites. </p>
<p>You should go immediately to a medical professional who can monitor your symptoms and determine whether the antivenom is necessary.</p>
<h2>Step 2: What bit you?</h2>
<p>If it’s safe to, collect the spider. If you don’t want to collect it, try to get a clear photo of the spider’s face, and another of its body from above; try to realistically remember the size of the spider.</p>
<p>Not all spiders live everywhere, so an expert is needed to identify which spider you’ve encountered. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=222&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=222&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=222&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=279&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=279&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98734/original/image-20151017-25112-1ug0uha.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=279&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Occurrence record map of funnel-webs (left, spiders from the family Hexathelidae) and redbacks (right, spiders in the genus <em>Latrodectus</em>).</span>
<span class="attribution"><span class="source">Maps from the Atlas of Living Australia.</span></span>
</figcaption>
</figure>
<p>Once experts identify which spider is responsible for the bite, doctors can determine what treatment is needed.</p>
<h2>Step 3: Treatment</h2>
<p>Spider venoms are complex chemical cocktails consisting of hundreds of different components. Each component has a unique role to play in the venom, and the activity of each individual component is very specific. </p>
<p>The individual components in spider venoms that are responsible for most of the activity are small proteins, or peptides, that contain a specific, highly structured three-dimensional scaffolding. We call those structured peptides toxins.</p>
<p>Antivenom is designed to neutralise the individual venom components that are dangerous. The <a href="http://www.csl.com.au/docs/822/652/Funnel%20Web%20Spider%20AV%20PI%20V6%20clean%20TGA%20approved%2018%20Sept%202013.pdf">antivenom</a> consists of purified immunoglobulins, which bind the venom toxins while they circulate in your blood. </p>
<p>Because the antivenom is designed to bind the toxins, not to treat by age or weight, the amount administered <a href="http://jnnp.bmj.com/content/75/suppl_3/iii40.full">will be the same</a> regardless of the size or age of the patient. </p>
<h2>Be prepared</h2>
<p>Try to avoid being bitten in the first place. In the case of redbacks, learn to recognise and avoid their <a href="http://australianmuseum.net.au/redback-spider">distinct webs</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/tvjhc6BXQDM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This video outlines the finer points of redback spider web design.</span></figcaption>
</figure>
<p>In the case of funnel-web spiders, be alert during their mating season (November to February) when males are likely to be out of their burrows. Their burrows also have a distinctive web, and generally you’ll be able to detect a funnel shape in the above-ground part of the web.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98732/original/image-20151017-25112-s475un.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A funnel-web spider burrow on Fraser Island.</span>
<span class="attribution"><span class="source">@DrMaggieHardy/author provided</span></span>
</figcaption>
</figure>
<p>If you are planning a trip and are concerned you’ll be in the same environment as these beautiful and rare animals, consider completing <a href="https://training.gov.au/Training/Details/HLTFA302B">a first aid course for remote situations</a>.</p>
<p><em>For more information about spider bites and clinical toxicology, visit <a href="http://www.toxinology.com">www.toxinology.com</a>.</em></p><img src="https://counter.theconversation.com/content/49232/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maggie Hardy receives funding from The University of Queensland and UniQuest Pty Ltd.</span></em></p>There are more than 45,000 species of spider, but only a handful are potentially dangerous to humans.Maggie Hardy, Postdoctoral Research Fellow, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/206032013-12-03T03:46:23Z2013-12-03T03:46:23ZSome things to know about the redback spider antivenom<figure><img src="https://images.theconversation.com/files/36028/original/bcr2jv49-1385354224.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Past studies have indicated the redback spider antivenom is effective.</span> <span class="attribution"><span class="source">Cathy/Flickr</span></span></figcaption></figure><p><a href="http://www.abc.net.au/news/2013-11-20/redback-anti-venom-doesn27t-work3a-new-research/5104048">Media reports</a> about the redback spider antivenom being ineffective caused a bit of a stir recently. <a href="http://www.smh.com.au/national/redback-antivenom-study-divides-australian-doctors-20131120-2xvt5.html">The articles</a> were based on research presented at a major toxinology conference in Dubai.</p>
<p>To understand how and why this could be and whether you should be worried, you will need some information about venoms and how antivenoms are made first.</p>
<p>Venoms are not only produced by snakes and spiders, but also by bees, scorpions, ants, fish, shellfish, the male platypus and other creatures. They’re used for a variety of functions including the immobilisation of prey, digestion and defence, and are a complex mixture of biologically active molecules. </p>
<p>Antivenoms work by binding to components of venom and neutralising them, and were first made to combat snake bites because they often have fatal consequences. </p>
<p>We now have antivenoms to combat bites and stings by snakes, spiders, jellyfish and other creatures, especially for those that may be fatal or debilitating. </p>
<p>Venoms from different species of snake are usually different mixtures of toxic components and venoms from spiders are different again, so we need to make different antivenoms for each one.</p>
<h2>How antivenoms are made and tested</h2>
<p>Antivenoms used in Australia are usually made by injecting small, sub-lethal doses of venom into horses. The immune systems of these horses then produce antibodies against components of the venoms. </p>
<p>A small amount of blood containing these antibodies is taken from the horse (the horse easily replaces this blood, just like when you donate blood), and the antibodies are separated from it.</p>
<p>The antibodies are then processed to make them more effective at binding to venom components, and less likely to produce allergic responses in the treated bitten person. </p>
<p>It’s thought the antivenom for one snake species may also be effective in neutralising venoms from other, unrelated species. This may be due to the fact that horses are used to produce antivenoms against different types of snakes at different times and may retain antibodies from previous immunisations for some period of time.</p>
<p>Testing antivenom is problematic. </p>
<p>There are ethical issues with gathering the highest level of evidence – double-blind, placebo controlled studies in which people are injected with venom, and some are treated with antivenom but others are not. </p>
<p>So, most of the antivenoms we currently use have been tested using animals. And there are extensive studies of instances where antivenoms have been used in people. </p>
<p>It’s also possible to do venom-antivenom binding studies in the laboratory. Antivenoms, you will recall, work by binding to and neutralising certain toxic components found in venoms. </p>
<p>Ideally, an antivenom neutralises the lethal components of the venom. But antivenoms don’t necessarily bind to all components of the venom, so not all its effects may be neutralised.</p>
<p>What’s more, as they are remnants of molecules made by a horse, antivenoms may result in severe allergic reactions in people. So, while antivenoms can save lives, they can cause problems in their own right as well.</p>
<h2>Redback antivenom</h2>
<p>Redback spider bites are not usually fatal in adults but tend to be more dangerous in children as the spider doesn’t necessarily inject a smaller amount of venom into a smaller person. </p>
<p>Redback spider antivenom is made by the pharmaceutical company CSL, which makes most antivenoms used in Australia. The company claims its antivenom is <a href="http://www.toxinology.com/generic_static_files/cslavh_antivenom_redback.html">effective against</a> all black widow spiders (the family of spiders to which the redback belongs), as well as some others. </p>
<p>But what of the news that this is not so?</p>
<p>The research the reports were based on was done by Geoff Isbister, a toxinologist at Newcastle’s Calvary Mater Hospital. He treated redback bite victims with analgesic drugs, but only gave half of them redback antivenom; the other half got a placebo. </p>
<p>Compared with the placebo group, the antivenom had very little effect, but it caused allergic reactions in 4% of those receiving it (remember the risk of this comes from the fact that we’re using antibodies made by horses as the basis of the antivenom). </p>
<p>Based on this, Isbister says the treatment of redback spider bites should be re-evaluated. But other toxinologists quoted in the news reports highlighted that past studies have indicated the antivenom was effective. </p>
<p>Where does this leave the concerned reader with a shed full of redback spiders? </p>
<p>Well, the best thing you can do for now is avoid getting bitten. Being careful where you put you hands and if you can’t see where you are putting them, wear gloves. </p>
<p>If you do get bitten, seek medical advice quickly, preferably at hospital as that’s where the antivenom is likely to be.</p>
<p>Meanwhile, the continual challenging of current knowledge is good science.</p><img src="https://counter.theconversation.com/content/20603/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Venning does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Media reports about the redback spider antivenom being ineffective caused a bit of a stir recently. The articles were based on research presented at a major toxinology conference in Dubai. To understand…Michael Venning, Adjunct Senior Lecturer in Health Sciences, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.