Top 10 World's Biggest Type of Spiders

27/08/2014 23:29

Top 10 World's Biggest Type of Spiders

10. Tegenaria Parietina

Tegenaria parietina is a rather rare European spider with a distribution from Northern Africa to Central Asia and has also been found in Uruguay and Argentina. In the UK it is sometimes known as the cardinal spider because of the legend that Cardinal Woolsey was terrified by this species at Hampton Court.
 

9. Nephila Edulis

Nephila edulis is a species of large spider of the Nephilidae family. It is referred to the common name edible golden silk spider or golden silk orb-weaver. They are commonly found in Australia, where it is found in both tropical and temperate regions, and in parts of New Guinea and New Caledonia. It has a large body size variability, females can reach a body length of about 23 millimetres, males about 6 mm. The cephalothorax is black with a white pattern on the back, and a yellow underside; the abdomen is grey to brown. The web is about 1 metre in diameter and protected on one or both sides by a strong "barrier" web. N. edulis breeds from February to May, and produces an average of 380 eggs.

 

8. Cerbalus Aravaensis

Cerbalus aravaensis is a huntsman found in the southern Arava Valley of Israel and Jordan. The species was first described by Gorshom Levy of the Hebrew University of Jerusalem in 2007, though news agencies later reported it in 2010 as a new discovery (with a slightly different spelling) by a team of biologists from the University of Haifa. The spider has a leg span of 14 centimetres (5.5 in), making it the largest member of the Sparassidae family in the Middle East. Males have a body length of 18.5–24.0 millimetres (0.73–0.94 in), while females' body length is 22.0–26.5 millimetres (0.87–1.04 in).
 
 

7. Phoneutria

Phoneutria has probably the worst reputation among the araneomorph spiders. In almost every published text, even in some non-fiction books covering this subject, they are described as "extremely dangerous", "extremely aggressive" and "(most-) toxic", "highly venomous", or just "deadly". There are also dozens of "true" field reports giving the impression that these spiders must be the pure evil. But this is actually just half the truth.

Talking about Phoneutria, we have to be aware that there are eight (valid) species, with different genetics, geographic distribution, habitat preferences, biology and natural history traits and that information we find just under “Phoneutria” is indiscriminately generalized (undifferentiated) information and might not be true for all the species in the genus.

Most Phoneutria species are quite large, and as a matter of fact the genus comprises the largest known araneomorph spiders. With a total body length of about 5 cm and a leg span of about 18 cm, some Phoneutria species earn the record of world's largest true spider, at least regarding body weight and body size (some sparassids and some Ancylometes have a greater leg span).

Phoneutria species show a distinctive defence behaviour (full thread display, see picture below), when they feel threatened. This behaviour is a "back-off"-signal that (if being ignored) will sooner or later lead to a biting attempt of the spider.

However, it should be emphasised here, that this behaviour is primarily defensive, although often mistaken for aggression. In rational terms, Phoneutria spiders only do the same as many other animals: They try to defend themselves when being threatened. At most some have a very low threshold to feel disturbed or threatened.

Important is that the spiders do not (attempt to) bite people by chance. Rather the opposite - from a spider's perspective it is quite costly to "waste" venom on humans. It takes time and energy to produce the venom which primarily serves to immobilize and eventually kill the prey and a spider that spent its venom on uneatable things may be unable to overcome prey soon after and may therefore have to hunger for a while. So, a spider should only be "willing" to give a "full bite", with venom injection, when it really feels threatened, like when it seems to be a matter of life and death (from the spider's perspective). And this is how biting accidents happen: People unaware of the spider's presence, make movements towards the spider, or even get a hold of them accidently, while e.g. sorting bananas. The nocturnal spider that seconds before was sitting in a banana stalk, hiding from the daylight, now finds itself in a stressful situation, threatened to be crushed/killed by the five-fingered predator that is now having the spider in its grip. The natural response of the spider to such a situation is a bite.

There is no doubt that the venom of some of the species is quite potent for mammals, including humans. Since there is not much information available about the evolution of these spiders, e.g. what triggered their defensiveness or their venom composition, we have to keep in mind that it may be a result of co-evolution of prey-predator interactions. Due to their size and the abundance of small amphibians, reptiles and mammals in their tropical environment it might have been an evolutionary advantage to have venom components effective on vertebrates. In combination with colour signals and defence behaviour (typical alarming ofPhoneutria), an effect of the venom on mammals was maybe evolutionarily “requested”. In fact there are mammalian predators of large wandering spiders, not us, but the coatis (Procyonidae - raccoons) and other small insectivore mammals. Hence, our “sensitivity” to the spider’s venom is probably just a coincidence.

 
 
 
 
 
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