World's Biggest Spider
The greatest spiders in the world by size include: tarantulas, orb weavers, wolf spiders, raft spiders, and Brazilian wandering spiders.
This site contains a short description of each. For those visitors only looking for information about the world's biggest spider, the answer is that it is the bird-eating tarantula.
The Bird-Eating Tarantula
The Latin name of the spider is Theraphosa Blondi. It is not aggressive, and in fact, it is a shy and timid spider. For some people, its hairs cause an allergic reaction that can be more severe than anything else the spider could do to a person.
Due to its size, it is also called the goliath bird eating tarantula.
In Brazil the biggest spider is the wandering spider. It can reach a length of 4-5 inches. The name wandering comes from the fact that, during the night, they walk on the jungle floor searching for prey rather than hiding in a burrow waiting for prey to come by. The name of the genus is Phoneutra which means murderess. Not only are wandering spiders enormous, they are also highly dangerous and should be avoided at all costs.
The raft spider, Latin: Dolomedes fimbriatus, is the most sizeable spider found in the United Kingdom. The size of these spiders is approximately one inch. They are very stout spiders capable of capturing relatively large prey, such as damselflies.
Golden Orb Weavers
The golden orb weaver (Nephila edulis) is one of the biggest spiders found in Australia. Their webs are so large that they can be spotted at a long distance both because of their size but also because of their yellow-golden color. Females are much larger than males and can reach a length of 4.5 cm or 1.3 inches.
Ancient fossils show a record of gigantic spiders million of years ago.
Recently a team lead by the Kansas-based scientist, Paul Selden, found a fossil of a large spider with legs of about 6 inches, or 15 cm. The scientists believe that the spider was large enough to catch small birds and bats.
The fossil was so well preserved that the scientist could see that it had bundles of hairs on its legs.
The spider lived 165 million years ago, which is more than the 6,000 years which according to creatonist, is the age of the world.
As spiders are invertebrates and have no bones and are rather fragile, they are not well preserved in the fossil record. Therefore, scientists have to evaluate if various structures of spiders of today are present or not. Only in amber inclusions (spiders caught in resin) can structures be observed with greater accuracy.
For some reason, many invertebrates are attracted to resin and are occasionally caught. Invertebrates in amber can be studied by scanning methods, also known as electron and transmission microscopy. However, spiders caught in amber are limited to forested areas. Spiders that lived elsewhere, and in places with limited vegetation and forests, were not caught in resin.
The scientist that found the gigantic 165 million year old fossil, Paul Selden, is the author of several articles about fossilized spiders.
The structures most often studied in fossils are: carapace shape and relative length and width of the legs.
Currently there are more than 1,099 different types of fossilized spider species1.
To some extent, classification 30-40 years ago was perhaps based a little too much on uncertain scientific information, such as juvenile structures in fossils that were not well preserved compared to some of the fossils found within the last 25 years, which are much better. Furthermore, a lot of findings were published in journals that were not peer-reviewed.
1. Selden, P.A. and Penney, D. Fossil spiders Biological Review (2010), Vol. 85, pp. 171-206.