h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I haven't been able to find any proof of the spider in question, but I did however read that it was discovered by scientists. Unfortunately, they did not elaborate where, when and how it was discovered.

My suggestion would be to leave that part out until you have evidence.

Then concentrate on the business of explaining the 'natural causes' question in a way that makes sense to a layman.

When it comes to finding the world's largest spider, I'm thinking that National Geographic might be a good source:

http://video.nationalgeographic.com/video/player/animals/bugs-animals/spiders-and-scorpions/tarantula_goliath.html

While large (Elektra is still shuddering), this spider is hardly 500 pounds.

The only ones that size appear to dwell on Gilligan's Island, which I believe to be a fictional place (until corrected by USGS or the CIA Factbook).

Hi there, I've taken my gloves off to answer this! No spider of 500 pounds has ever lived on this planet or is ever likely to. In fact I don't know of any fossil spiders known to be any bigger than the biggest ones currently living, and they are the bird-eating spiders, Teraphosa blondi, as is mentioned in this article. But they are very, very far from 500 pounds/225 kg ... in fact they are only known to reach 170 grams/ 6 ounces.

Similarly there are no 'giant water spiders' that have 8-ft leg spans. The diving-bell spider, which is the only fully aquatic spider, is a fairly normal-sized spider ... I am not sure but I'd be surprised if its leg span exceeds 2 inches.

Now for perspective on this. Spiders are arthropods - animals with jointed limbs and 'exoskeletons', i.e. their skeletal support is on the outside rather than in the middle of the limbs as those of vertebrates (backboned animals) like ourselves. This immediatly puts constraints on their size. The muscles have to be on the *inside* of the skeleton, which isn't the optimal arrangement, giving them a muscle-strength to weight ration that is unfavorable compared to vertebrates. So, a very big arthropod is relatively weak for its size.

Also, the breathing system of arthropods is not as efficient as our lungs are. So, very big arthropods cannot take in as much oxygen, relatively, as vertebrates can. This, too, limits their size.

OK so how big CAN arthropods get? Note, not spiders. The biggest arthropods alive are members of the Crustacea, namely the Japanese giant spider crab, and the American lobster. The spider crab can reach a width (claw-to-claw) of 3.6 m/12 ft ... but it has exceptionally long claws, and its body is small for its size. It is known to reach 19 kg/40 lbs in weight. It is exceeded in mass by the American lobster, which has been known to reach 20 kg /44 lbs, making it the heaviest known crustacean as well as the heaviest (known) living arthropod.

Both these are living in the oceans, where water buoys up their weight. They would have a hard time walking or in any way moving about on dry land.

But there is a very big arthropod living on land: the Coconut Crab, also known as the Robber Crab. They occur on islands, and climb coconut palms, cutting down the coconuts with their huge claws. They're actually not crabs, but relatives of the Hermit Crab which itself is not a crab either but a kind of lobster. The coconut crabs are known to reach weights of 4 kg/9 lbs although there are unverified claims of ones of 14 kg/30 lbs.

In the past there were bigger arthropods. The biggest ones living in the sea were the Eurypterids, called sea scorpions, though they were not scorpions but a different, now extinct group. The biggest ones reached 2.5m/a bit over 8 ft in length. I don't know what they weighted ... but they were flattish, so I don't think much over 50 kg. On land the biggest known arthropod EVER was the Arthropleura, a millipede-like creature that also reached 2.5 m/8 ft. It, too, was flattish, and long-bodies, and I'd be surprised if it got to much over 20 kg ... but still, that is enormous for a land-living arthropod.

At roughly the same time, there existed dragonflies as big as pigeons ... insects that big are completely impossible today. Scientists today still aren't sure why giant arthropods lived back in the Carboniferous. One theory is that the oxygen content of the atmosphere was significantly higher, meaning that their breathing and muscular action would have been more efficient.

OK so that is more or less what is known about giant arthropods, for perspective on the likelihood of a 500-lb spider.

Thanks for that buddy, I did however see on google, a site that claimed scientists discovered a 500Lb spider, but obviously, thanks to your insight, that was just not the case, I had a feeling that it wasn't true, but who was I to argue with someone else's so called research on that site. Anyway, thank you so much for clearing that up for us.

Thank you, thank you, Willem.

Elektra is hugely relieved. She is NOT a fan of spiders.

It's a pleasure! Anything else?

If there is, you'll be the first to know, thanks again

Sorry, what you actually read was a 'headline' in google about a 500lb 'spider'

It was a photograph of a 500lb girder being held up by a 'spider' wire.

I do hope you are being more careful with the rest of your research, as your article will be checked closely for plagiarism

lil x

Yes, been very careful with it. Thanks for that