It is said that arachnophobia, or the fear of spiders, is common among people around the world who have an inherent aversion to these creepy crawlies. Just the thought of coming into contact with one is something most of us dread.
Lawn wolf spider in Huai Kha Khaeng.
But there are a few souls out there who love them and even keep spiders as pets. The vast majority of us, however, tend to just stay out of their way. Some spiders can give a nasty bite, although fatalities are rare.
Like all creatures, spiders have to face life's difficulties such as finding food and mates, producing offspring and fending off danger. However, spiders are the ultimate predator, and have been on the planet for a very long time.
Many people mistake spiders for bugs, but the ancestry and anatomy of spiders are different from those of insects. Spiders have eight legs not six, and their bodies are divided into just two parts rather than three.
The family tree of spiders is as follows: Jumping spiders, the largest and most highly evolved family, together with hunting spiders and web spinners make up the main group. Tarantulas and trapdoor spiders and others in this group plus "six-eyed" spiders make up modern-day creatures.
Spiders are a very ancient group that first appeared during the Devonian period, almost 400 million years ago. By the Carboniferous period (300 million years ago), when insects were still relatively little developed, many highly evolved spiders already existed. These arthropods appeared about 100 million years before the first vertebrates or back-boned animals.
Scientists have identified some 43,244 species around the world. More than 230 species have been recorded in Thailand with many more to follow. There are only a few people researching spiders here and so knowledge about them is rather limited.
Dr Patchanee Vichuitbhun and Prasit Wongprom of Kasetsart University in Bangkok are the country's leading arachnologists. Five graduate students are also working on spiders.
Ornamental tree-trunk spiders in Lampang. The male is the one seen at top left.
Together with their eight-legged relatives such as scorpions, harvestmen, mites and ticks, spiders form the class Arachinda. Spiders alone represent the order Araneae and are classified in a family tree that numbers three sub-orders and 111 families.
Spiders are found virtually everywhere: in the house, in the garden, in forests, in caves, and in most other terrestrial habitats throughout the world. A few species live under water and some even in the marine tidal zone. The only place with no spiders is Antarctica.
While the greatest diversity of species occurs in tropical rainforests, spiders are also very well represented in temperate woodlands and grasslands. Spiders thrive wherever there is rich vegetation and plenty of insects or other arthropods.
Thailand has plenty of big scary-looking spiders but only a few species will actually bite a human. Luckily, deaths from spider bites are very rare _ less than three per year across the whole world and these are generally the result of allergic reactions.
Although virtually all spiders possess venom, only a small number of species, probably fewer than a hundred, have a sufficiently potent and effective bite to be of medical importance. Spiders use venom to quickly immobilise or kill their prey. It is also used in defence against animals, including man, but this is only a secondary purpose.
Thailand is home to very few spiders that are dangerous to people. However, the brown widow is the most venomous. Tarantulas and golden orb weavers attract notoriety more for their size than their bites. But you must monitor all spider bites carefully to avoid the development of secondary infections.
The spiders of medical importance in Asia include widow and cupboard spiders, also called brown house spiders or false widows (family Theridiidae) whose venom contains neurotoxins. Though not especially venomous, a number of Asian tarantulas or bird-eating spiders can also be regarded as potentially dangerous.
In many countries around the world, the practice of keeping spiders as pets seems a bit extreme to most of us, especially if it is highly poisonous. A few years ago, a brown widow escaped from someone's house and it made front-page news in some newspapers here.
A trip to Chatuchak Market's pet section can provide one with a spider. There are rows and rows of shops catering to anyone who wants one. Most species on display are tarantulas from South America, however there are some Asian ones too.
It seems most of these shops act with impunity and no matter how many raids the Department of National Parks makes, they just pop back up and carry on. It is really disheartening to see how these mafia-type groups continue to operate.
Most people are not aware of the dangers of keeping a tarantula that will flick off barbed hairs when alarmed, causing hairs to become imbedded in the eyes and hands of the pet owner. Eye surgeons might be able to remove some hairs from an eye but many are likely to remain, causing a serious medical ailment.
Something else the public needs to worry about is the brown widow, an invasive species from North America related to the very famous and notorious black widow. The brown species is now confirmed in 20 provinces in Thailand, and probably came over on ships. The bite from one of these is extremely painful but there have been no fatalities here yet. There is no antivenin for this species. Probably the most remarkable thing about spiders is the silk they make.
We humans have not produced anything as strong, light and elastic. Spider silk is twice as strong as the silk produced by insects like the silkworm moth.
Besides the construction of webs, spiders have many other uses for their silk such as making nests, attaching trapdoors, furnishing burrows and constructing egg cocoons. Other uses are to wrap and mummify their prey. It truly is amazing stuff.
The coupling of two predatory and often shortsighted creatures can be a hazardous affair, particularly for the smaller male. In spiders, the battle of the sexes is very intense and in some species, the male ends up being eaten after mating with the female. The size difference between the male and female can be seen in the photograph of the ornamental spider.
Spiders are extremely important in the balance of nature and play a big role in the elimination of vast numbers of pest insects. These unique creatures are allies of farmers and growers.
Yet even if they were not useful, spiders would still deserve our whole-hearted respect as one of the most diverse and fascinating animal groups in the natural world.
Some people may disagree but if you bump into a spider, please let it go. These ancient creatures really need our protection.
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FROM LEFT - Argiope sp. spider in Thung Yai - Bird-eating spider - Orb-web spider in Angkor Wat - St Andrews cross spider in Chiang Mai.
Decoy spider in Chiang Mai.
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About the author
Writer: L. Bruce KekulePosition: Writer
Article source: http://www.thethailandlinks.com/2012/11/29/web-of-intrigue/
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