1
Giant spider fossil found in Mongolia
20 April 2011
I developed an appreciation of spiders around age 10. I came down with one of those childhood diseases - chicken pox, mumps, or measles, I forget which now - and spent a week in bed. I was a voracious reader even then, but I had only one unread book on hand, a library title taken out for some school project. It was Jean Henri Fabre's 1912 work, The Life of the Spider. So that's what I read all week. It was the first 'adult' book I read in its entirety. And I relished it.
Fabre begins his book by writing, "The Spider has a bad name: to most of us, she represents an odious, noxious animal, which every one hastens to crush under foot. Against this summary verdict the observer sets the beast’s industry, its talent as a weaver, its wiliness in the chase, its tragic nuptials and other characteristics of great interest. Yes, the Spider is well worth studying, apart from any scientific reasons; but she is said to be poisonous and that is her crime and the primary cause of the repugnance wherewith she inspires us. Poisonous, I agree, if by that we understand that the animal is armed with two fangs which cause the immediate death of the little victims which it catches; but there is a wide difference between killing a Midge and harming a man. However immediate in its effects upon the insect entangled in the fatal web, the Spider’s poison is not serious for us and causes less inconvenience than a Gnat-bite. That, at least, is what we can safely say as regards the great majority of the Spiders of our regions."
Fabre was, as Wikipedia notes, one of those keen naturalists of the late 19th and early 20th centuries who, like Darwin before him, have a fascination for the natural world and learn about it through both keen observation and scientific research. Fabre had the talent of writing in an engaging, colloquial manner that made his works accessible to those who eschewed the more clinically detached, journalistic mode of his contemporaries.recording. His passion for his subjects come across in his written works.
His work, now almost 100 years old, inspired my interest that has lasted the latter half of that century. I am also keenly interested in paleontology.
So it was with delight and astonishment that I read on the BBC Web site about the discovery of a giant spider, 165 million years old, found in Mongolia. Nephila jurassica, as she has been named, would have had a leg span of some 15cm and is the largest known fossil spider yet found. For those of us on imperial, that's six inches. Fossil insects are rare simply because soft body parts do not fossilize as well as bones and teeth. Spider fossils are generally very rare.
This fossil spider is larger than the giant spider recently discovered in the Israeli desert, Cerbalus aravensis. It's as big as the giant camel spiders that got widespread coverage during the Iraqi war (despite the scary stories, camel spiders are fast and aggressive, and have a nasty bite, but are not very dangerous). Some of the media reports about camel spiders have greatly exagerrated their size, speed and diet.
These are big, but not the maximum size for spiders in the post-Carboniferous* world. The nature of their physiology places limits on physical size, but they can get pretty big in the right environment. Most spiders have soft bodies, and the larger they grow, the more vulnerable their bodies are to damage, especially from falls. Many spiders breathe with a primitve 'book lung' that is inefficient for any body much larger than these examples (related arachnids, mites and harvestmen, and some spiders, breathe solely through tracheae). The size of a spider is often mistaken by the viewer since the leg span can be very large compared to the body size.
The two largest spiders known are both living species from tropical lands. The smallest of the two is the Amazonian Goliath birdeater, a tarantula with a leg span up to 30cm (12 inches). This also seems to be reaching the maximum size for the body of a spider. Slightly bigger than that (although with a lighter, smaller body) is the Vietnamese Giant hunstman. Neither are particularly dangerous to humans and will not normally attack or bite humans unless threatened or hurt. Most live on invertebrates, but may also eat small vertebrates like rodents and reptiles.
Despite what cryptozoologists or wacky Web sites claim, there are no five-foot spiders simply don't exist because their physiology would not permit such growth in today's atmosphere. And what was once thought to be a real giant spider from the Carboniferous - Megarachne, with a 34cm body and 50 leg span - has been more recently identified as a eurypterid, a species of water scorpion.**
The largest spiders in Ontario are the 'dock spiders' or Dolomedes scriptus which can have a leg span of 10cm. While big, and the females are often very protective, these semi-aquatic, nocturnal hunters are again not very dangerous. Most people encounter them when humans inadvertantly approach one, and a female guarding her eggs may make aggressive displays, even charge a perceived threat.
None of these giants are as dangerous as the much smaller brown recluse spider which, again, is not very aggressive, although its venom can be potentially be necrotic (although rarely despite its bad reputation).
This fossil Nephila is also the oldest specimen of her species, and makes Nephila the oldest know spider group still extant. Spiders are at least 300 million years old, from the Carboniferous, although there are earlier, related arachnids, dating from the Devonian.
Nephila belongs to an existing family of orb web spinners, found around the globe today in both tropical and sub-tropical regions. Nephila females - this fossil is a female - are the web spinners and can grown quite large. Some of her modern counterparts weave orb webs up to 1.5m in diameter. Males of the species are diminutive and like many spiders, do not weave, but mostly exist for mating. This fossil shows that this sexual dimorphism may have existed since the Jurassic age, although a Cretaceous example of the species suggests males were of a similar size to females.
Orb web spinners generally feed on insects that get caught in their webs, although there have been documented reports of the larger ones in Australia eating birds that got caught in their web. Small reptiles, fish and small mammals have also been identified as spider prey. None are large enough to prey on your family pets, however.
Spiders may repulse or frighten us, but they're seldom dangerous and generally beneficial. Most are shy and not aggressive. I prefer the predator over their prey. But then I don't suffer from arachnophobia, in part thanks to reading Fabre's entertaining work at a young age. Perhaps we could cure more people of this in future by teaching our children to better value and respect nature before they develop their adult phobias and habits.
~~~~~
* During the oxygen-rich Carboniferous period, many insects and other arthropods grew to gargantuan size. The dragonfly, Meganeura, had a 75cm (30in) wingspan.
** Spiders pale in comparison to their size their hardshelled arthropod cousins can grow to. Even crayfish are usually bigger than most spiders, but there are much larger lobsters and crabs. The giant Japanese spider crab can have a leg span of 3.7m (12 ft)! It's odd that lobsters and crabs do not generate the same sort of fear as spiders in most people.
Fabre begins his book by writing, "The Spider has a bad name: to most of us, she represents an odious, noxious animal, which every one hastens to crush under foot. Against this summary verdict the observer sets the beast’s industry, its talent as a weaver, its wiliness in the chase, its tragic nuptials and other characteristics of great interest. Yes, the Spider is well worth studying, apart from any scientific reasons; but she is said to be poisonous and that is her crime and the primary cause of the repugnance wherewith she inspires us. Poisonous, I agree, if by that we understand that the animal is armed with two fangs which cause the immediate death of the little victims which it catches; but there is a wide difference between killing a Midge and harming a man. However immediate in its effects upon the insect entangled in the fatal web, the Spider’s poison is not serious for us and causes less inconvenience than a Gnat-bite. That, at least, is what we can safely say as regards the great majority of the Spiders of our regions."
Fabre was, as Wikipedia notes, one of those keen naturalists of the late 19th and early 20th centuries who, like Darwin before him, have a fascination for the natural world and learn about it through both keen observation and scientific research. Fabre had the talent of writing in an engaging, colloquial manner that made his works accessible to those who eschewed the more clinically detached, journalistic mode of his contemporaries.recording. His passion for his subjects come across in his written works.
His work, now almost 100 years old, inspired my interest that has lasted the latter half of that century. I am also keenly interested in paleontology.
This fossil spider is larger than the giant spider recently discovered in the Israeli desert, Cerbalus aravensis. It's as big as the giant camel spiders that got widespread coverage during the Iraqi war (despite the scary stories, camel spiders are fast and aggressive, and have a nasty bite, but are not very dangerous). Some of the media reports about camel spiders have greatly exagerrated their size, speed and diet.
These are big, but not the maximum size for spiders in the post-Carboniferous* world. The nature of their physiology places limits on physical size, but they can get pretty big in the right environment. Most spiders have soft bodies, and the larger they grow, the more vulnerable their bodies are to damage, especially from falls. Many spiders breathe with a primitve 'book lung' that is inefficient for any body much larger than these examples (related arachnids, mites and harvestmen, and some spiders, breathe solely through tracheae). The size of a spider is often mistaken by the viewer since the leg span can be very large compared to the body size.
The two largest spiders known are both living species from tropical lands. The smallest of the two is the Amazonian Goliath birdeater, a tarantula with a leg span up to 30cm (12 inches). This also seems to be reaching the maximum size for the body of a spider. Slightly bigger than that (although with a lighter, smaller body) is the Vietnamese Giant hunstman. Neither are particularly dangerous to humans and will not normally attack or bite humans unless threatened or hurt. Most live on invertebrates, but may also eat small vertebrates like rodents and reptiles.
Despite what cryptozoologists or wacky Web sites claim, there are no five-foot spiders simply don't exist because their physiology would not permit such growth in today's atmosphere. And what was once thought to be a real giant spider from the Carboniferous - Megarachne, with a 34cm body and 50 leg span - has been more recently identified as a eurypterid, a species of water scorpion.**
The largest spiders in Ontario are the 'dock spiders' or Dolomedes scriptus which can have a leg span of 10cm. While big, and the females are often very protective, these semi-aquatic, nocturnal hunters are again not very dangerous. Most people encounter them when humans inadvertantly approach one, and a female guarding her eggs may make aggressive displays, even charge a perceived threat.
None of these giants are as dangerous as the much smaller brown recluse spider which, again, is not very aggressive, although its venom can be potentially be necrotic (although rarely despite its bad reputation).
This fossil Nephila is also the oldest specimen of her species, and makes Nephila the oldest know spider group still extant. Spiders are at least 300 million years old, from the Carboniferous, although there are earlier, related arachnids, dating from the Devonian.
Nephila belongs to an existing family of orb web spinners, found around the globe today in both tropical and sub-tropical regions. Nephila females - this fossil is a female - are the web spinners and can grown quite large. Some of her modern counterparts weave orb webs up to 1.5m in diameter. Males of the species are diminutive and like many spiders, do not weave, but mostly exist for mating. This fossil shows that this sexual dimorphism may have existed since the Jurassic age, although a Cretaceous example of the species suggests males were of a similar size to females.
Orb web spinners generally feed on insects that get caught in their webs, although there have been documented reports of the larger ones in Australia eating birds that got caught in their web. Small reptiles, fish and small mammals have also been identified as spider prey. None are large enough to prey on your family pets, however.
Spiders may repulse or frighten us, but they're seldom dangerous and generally beneficial. Most are shy and not aggressive. I prefer the predator over their prey. But then I don't suffer from arachnophobia, in part thanks to reading Fabre's entertaining work at a young age. Perhaps we could cure more people of this in future by teaching our children to better value and respect nature before they develop their adult phobias and habits.
~~~~~
* During the oxygen-rich Carboniferous period, many insects and other arthropods grew to gargantuan size. The dragonfly, Meganeura, had a 75cm (30in) wingspan.
** Spiders pale in comparison to their size their hardshelled arthropod cousins can grow to. Even crayfish are usually bigger than most spiders, but there are much larger lobsters and crabs. The giant Japanese spider crab can have a leg span of 3.7m (12 ft)! It's odd that lobsters and crabs do not generate the same sort of fear as spiders in most people.
