World's Most Dangerous Spider on Coin|
July 01, 2013
The exciting series of Australia’s “Deadly and Dangerous” animals on coins struck by the Perth Mint and issued as legal tender under the authority of the Government of Tuvalu continues with a species of the deadly funnel-web spider, but regrettably the species name is not on the coin. Because of its notoriety, I am assuming the species on the coin represents the ground-dwelling Sydney species (Atrax robustus), which many consider to be the world’s most dangerous spider.
Also issued in this series is the yellow-bellied sea snake (Pelamis platura) coin, which will be covered in a forthcoming article. The sea snake is of special interest to me because sight records have been recorded near my home in Long Beach, Calif. There are sight records in 1961 in L.A. Bay (Los Angeles?), 1983 in San Clemente and 1985 in the San Diego area. The local university where I taught had a preserved specimen in its Vertebrate Collections.
Sydney funnel-web spider
There are 31 species of Australian funnel-web spiders in three genera. All occur in eastern Australia. The male Sydney funnel-web spider has accounted for all known 13 human fatalities and many of non-fatal bites in Australia. It dwells within a 100 mile radius of Sydney, New South Wales.
Bites from any species of funnel-web spiders should be considered potentially dangerous, but three species in addition to the Sydney species are considered life-threatening. These are: Blue Mountains funnel-web spider (Hadronyche versuta) southern and northern tree-dwelling funnel-web spiders (H. cerberea and H. formidabilis). All three are found mainly in northeastern New South Wales, but the northern species also extends into southeast Queensland. The northern species is the largest species, attaining a length of about 2 inches! The Sydney and southern tree dwelling species are common around Sydney.
Funnel-web spiders are big spiders. The body is divided into a front black part where four pairs of legs (all spiders have four pairs of legs) and other movable parts originate and a bulbous rear abdomen (dark brown). The size range is 0.5 inch to almost 1.5 inches. Females are larger than the more dangerous males. Both sexes are very aggressive and if approached will rear up, exposing their very long fangs in a striking position. This maneuver probably will cause many people to hastily back off. The fangs are quite hard and are said to be capable of penetrating a child’s fingernail.
In Sydney suburbia, this species prefers moist, cool habitats and constructs its white funnel-shaped web underneath rocks, crevices, in and under rotted logs, or digs a burrow that may be 12 inches deep. Around human dwellings they like dense shrubs or rocks in gardens to dig their burrows, and people working in their gardens may find them anytime. It is said the way to recognize a funnel-web spider’s web is the presence of several web trip-lines extending out from the entrance. If prey walks into these lines the spider rushes out and injects venom from its large fangs. What is scary is sometimes this spider is found in colonies of as many as 100 individuals.
What do these spiders eat? It may surprise you that a food item may be a lizard. Picture a small lizard stepping on one of the spider’s trip-lines. The spider that has been waiting at the entrance to its burrow rushes out and stabs the lizard, maybe repeatedly, with its stout fangs injecting lethal venom, which immediately paralyzes or kills the lizard. But the spider has no teeth or moving jaws, so how does it eat the lizard? The lizard is dragged into the burrow, and the spider punctures it with its fangs allowing digestive enzymes from the mouth (not from fangs) to flow into the lizard’s tissues, which rather quickly liquefy. Then, it sucks the liquefied tissue into its stomach and repeats this until the lizard is just skin and bones. Small frogs and snails but mainly just about any insect is eaten.
It takes a few years for males to sexually mature, and they tend then to leave their burrows to become wanderers chiefly in summer and autumn. They search for females who remain in their burrows, and often these males enter human dwellings especially during rainstorms. During their wanderings, they may aggressively prey on mainly insects for food. In preparation for mating, the male spins a specialized web and deposits on it a small drop of sperm. This is then moved to a mating organ on one of the appendages near the mouth. The search begins. Chemicals in a female’s trip line aid a male in locating females. When the male finds a female, both rear up and begin to spar. The male uses spurs on his front legs to prevent the female from stabbing and eating him. He then manages to deposit the drop of sperm into her genital opening and flees. She then spins an egg sac and deposits perhaps 100 eggs to be fertilized. The male dies after about nine months, but females can live to be 10 years old.
You will notice I stated earlier that the male Sydney spider is the most dangerous. The dangerous red-backed spider in Australia and the black widow spider in the U.S. are females. The male funnel-web is the most dangerous but not because of size since males are smaller than females. It is due to the venom of the male being five times more toxic than the female. Curiously, humans and monkeys are the most susceptible of any mammal. For example, the venom does not affect rabbits. According to an account of this spider from the Australian Museum website, “The answer lies in a combination of spider behavior, venom chemistry, and even colonial politics.”
I indicated above that an aspect of male behavior is that they are wanderers. All it takes is a small amount of male venom in a human and the nervous system causes twitching of muscles and also produces profuse perspiration, tears and saliva. But the toxic effects are just getting started. Blood vessels are effected that can lead to shock and a coma due to brain damage. Death may follow if first aid and/or antivenom are not given.
These reactions are due to a toxin in the venom called “Robustoxin” that is absent from female venom. (Another source called the toxic element “Atraxotoxin.”) If immediate treatment is given, the effects are said to subside after few hours. The antivenom has been available since 1981 and is now widely available in hospitals. No deaths have been recorded since its introduction.
What kind of first aid is most effective? It is termed the “Pressure/Immobilization method” that slows spread of venom throughout the body, but it must be applied quickly. This method is used only for funnel-web bites and not for red-backed spider bites. Let’s say the bite is on the ankle area. A pressure bandage and a rigid splint for immobilization should be used. Starting at the bitten area, wrap the bandage firmly but not too tightly up the entire length of the leg to the groin area. The victim should remain calm and transported to a hospital by ambulance if possible to minimize movement. (I wonder how many victims can remain calm?) How does “colonial politics” play a role in these dramas? Some 4 million people live in the Sydney area, which is the center of the spider’s distribution, and the likelihood of a run-in with a spider is greater than in rural regions.
“This situation, of course, stems from a political decision made in London more that 220 years ago, to establish a colony in ‘New South Wales’ at Sydney Cove, a site nominated by Captain James Cook after his voyage of exploration,” according to the Australian Museum site.
So, a spider bite victim can blame Captain Cook for his misfortune!
The online site for the Australian Museum’s account of funnel-web spiders is http://australianmuseum.net.au/Funnel-web-Spiders-Group.
Questions and comments are welcomed. Contact me at firstname.lastname@example.org.
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