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It's a Spider's World! (and Introducing Poecilotheria rajaei)
Arachnids never lose power to fascinateClick thumbnail to view full-size
Arachnids are an evolutionary success story.
This contributor has published many articles on Hubpages and elsewhere about insects and "creepie-crawlies, in particular, arachnids. They, like snakes, have been interesting because many of them have unecessarilly aroused fear in people who should really know better.
Spiders have a lot of misinformation spouted and published about them. One sobriquet designed to confuse is "dangerous." I suppose one could divide this into dangerous and potentially dangerous. Whether any wild creature is dangerous depends unsually in large part to whether the victim was stupid or genuinely attacked for one of two main reasons: They are 1) Defense or 2) Seen as Prey. Some creatures on the planet are the most dangerous because they always, given the right conditions, see mankind as prey. This includes crocodiles, polar bears and, to a lesser extent, sharks. Other large predators such as lions, tigers, other bears, etc., are sometimes predatory towards man, but more often maul and kill for defense and otherwise ignore us or shy away from our guns.
When we get into the world of the insect and the arachnid, only biting insects like mozzies see us as a meal on the hoof. We might include reduuvid bugs (Chagas) and vampire bats here and there are a few more blood suckers. But no spider to my knowledge sees the giant, man, as prey; same for scorpions and tarantulas. So their attack will be defensive, with the possible exception of the Brazilian Wandering Spider who does have a nasty disposition and the worst venom to go with it. (Check your Tesco bananas!). But of the handful of truly venomous spiders that remain, they won't bite you if you don't compromise their safety or otherwise annoy them.
Of course, where creatures are concerned laws are like piecrusts, made to be broken; in the tiny organ that serves as a brain for these simple creatures, mistakes are made. Brown Recluse spiders will get in your bed and your shoes and might bite you if you move over them or lower a large foot on top of them...Black Widows resent being moved from behind the water tank! But this is still really covered by defensive biting.
Tarantulas can be mostly handled with impunity and won't think of biting...even if they do, it may be a "dry" warning nip from those large fangs, no venom injected. We have found that about one half of tarantula bites are of this kind; of the other 50%, venom is injected with some mild to fairly serious symptoms being experienced (but no reported deaths to date). Usually, a greater menace is their ability to throw-off "urticating hairs" which can get in an aggressor's eyes, painful and even blinding. The New World 'taras are the worst urticators, Old World tarantulas have stronger venom and less ability to urticate.
Snakes are also capable of witholding venom from a strike and rattlesnakes often use this option if they were not unduly threatened. They don't want to kill us, just get us to "walk on by" and leave them alone.
The terms dangerous and venomous are interchangeable. But some large spiders, particularly the Brazilian and the Sydney Funnel Web should be seen as extremely dangerous because if they do bite with malice aforethought you might well be dead in short order. You only have to see a large female funnel web, 3/4 inch fangs dripping with venom as she rears to strike to know that your health is in danger if you don't move out of range quickly. The Brazilian is reported to have chased people or their pets round their houses! And most spiders can also jump!
But Black Widows and Recluses, among many smaller yet venomous spiders, once located, can't be thought of as dangerous...and the same applies to the less intelligent scorpions who never attack man if not seriously molested.
In the UK, all the house spiders and wolf spiders who visit or live in your homes are completely harmless and should be either left alone or removed carefully and released some distance from your house.
A New Species
It's quite extraordinary, but we are finding new species of arachnids all the time. Like the Poecilotheria rajaei, found in Shri Lanka recently. This tarantula is one of the world's largest, positively huge with an 8-inch leg span. (that about covers your face!). It is also one of the fastest moving and most venomous, its bite has made some human victims ill, but it is still not seen as fatal to man, but a killer to all small mammals, reptiles and birds, etc.; some reports have it killing small pets.
Rajeai is related to the world's largest tarantula, the South American Goliath, often misleadingly called the "bird-eating tarantula." Actually, rajeai probably puts paid to more birds than does poor old Goliath, as it is mainly aboreal, only abandoning its usual habit due to forestation and man's destruction of its habitat as villages and towns expand. This why it has been such a long time waiting discovery, but several family members have now been found in Shri Lanka and India.
In fact, spiders are predators of many small animal groups. Every continent apart from Antarctica has bat-catching and consuming spiders. Many countries (including the UK) have fish-eating spiders. They can immobolise fish twice their weight and do so fast with a powerful neurotoxin. None of these arachnids are a danger to man which may be a good thing as their venom must be some powerful substance to stop fish and bats in seconds! Many fish were probably investigating the spider's tantalising front legs in order to eat them...a real case of Shakespeare's the "Biter was Bit!"