Recently there has been a surge in the spider population in my area and I've had the opportunity to observe numerous specimens of tegenaria agrestis
(aka the hobo spider), tegenaria gigantea
(giant house spider which is closely related), a number of wolf spiders and of course the ubiquitous orb weavers which hang in groups of three or four from every tree and post.
This has got me thinking about how much irrational worrying some people do about these little eight-legged dudes and dudettes and how such generally docile and harmless creatures can be so reviled and misunderstood, to the point of being killed on sight in many instances.
So lets get right down to it and start to replace spider anxiety with spider fascination. First up; crab spiders:
Similar in body shape to the crustaceans after which they are named, these spiders can crab-walk around sideways and backward and all that. They are active hunters and catch prey by hiding wherever it can be found, such as on plants, and striking when prey draws close. A number of species make use of camouflage to remain undetected:
Some south american species take it a step further and mimic the Cephalotes
ant, an arboreal gliding ant which is the exclusive diet of a crab spider species:
(Note in the above how the spider carries its catch in the manner of an ant carrying a dead fellow, so as not to alarm future meals)
This next picture is not a crab spider (it is a salticid or jumping spider) but related to the above, notice how the spider uses its forwardmost pair of legs to imitate antennae:
Lastly we have Sicarius
, a genus of spider which resembles a crab spider but is actually more closely related to the recluse and lives in arid deserts in Africa and South America. Known for their burrowing behavior, this spider carries potent necrotic venom which can cause painful lesions, however these spiders are unlikely to come into contact with humans because of their distribution and only bite if threatened and cornered or in defense of young spiderlings. This spider is known colloquially as the six-eyed sand spider:ON THE TOPIC OF THE BROWN RECLUSE, HOBO SPIDERS, WIDOW SPIDERS, AND THAT HELLHOLE CALLED AUSTRALIA
Now I'd be remiss to avoid mention of the few species of spider which can deliver bites considered medically significant. I will be focusing on widows, the recluse, hobo spiders and the Sydney funnel-web spider, as these are the spiders most often in contact with people which one might be concerned about.
The Sydney funnel-web (Atrax robustus
These guys are major league assholes (the males in particular) and should be exterminated if found to be living near human populations. As their name might suggest they live in a densely populated part of Australia and can be found wandering freely like they own the place during their mating season, in this case almost every spider encountered will be male since the females do not wander and tend to camp the tubular web burrow (hence the other part of their name). What makes these spiders very unusual (and I stress this because this is a very rare characteristic) is that these spiders mount a very aggressive defense with little provocation. They will initially assume the "warning stance" pictured above and if the intruding human moves closer the spider will strike and deliver a "wet" (using venom) bite almost every time. Also unusual for spider self-defense, these spiders will strike multiple times with their large chitinous fangs, which guarantees a large dose of the compound atraxotoxin which is very harmful to primates.
Australia is also home to the Northern Tree funnel-web spider Hadronyche formidabilis
, which is more dangerous than Atrax robustus
but isn't as agressive or generally found near population centers.
Although these spider species should not be taken lightly, they speak more to the fact that Australia is a primordial hellhole of giant biting, stinging, and people maimin' flora and fauna than to any general trends among spiders. I mean shit, even the fucking trees in Australia will get you!
Widow spiders:U.S.A! U.S.A!
Widows are spiders of the genus Latrodectus
, they are distributed worldwide and take on a stunning array of appearances. However the ones you're thinking of are almost all found in wram parts of the US of A, where they have acquired a fearsome reputation that is only partially deserved. The reason these spiders can deliver very potent bites is the very large venom sacs of the female, which can cause Latrodectism, a clinical syndrome caused by the neurotoxic venom Latrotoxin. This condition can cause you to have a shitty couple months before it clears but its rarely life-threatening (ie cases of allergic reaction to spider venom), therefore Antivenom is generally reserved for use only when absolutely necessary. Due to the low mortality rate, the risk of major injuries or death due to anaphylaxis or serum sickness are greater than the risk of death due to the venom itself.
Except in australia where they use antivenom more liberally, not a big suprise all things considered.
However the bite of the female black widow is basically the only reason widows should be considered dangerous, as the males venom is as harmless as that of the majority of spiders. Likewise almost all other widow spider species can deliver bites which are midly irritating at worst, and most spiders will deliver "dry" (non-venomous) bites when acting in self defense the majority of the time. Of course this is only if they are trapped/pinched somehow in such a way that running away is no longer an option. I recommend wearing gloves when taking wood piles in from outside if you live in areas known to have black widow populations, as they are known to make their homes among these and therefore pose a risk if pinched against the wood by a hand.
The brown recluse (Loxosceles reclusa
) aka the "violin spider":
This one has a fearsome reputation too, but the actual actual danger posed by its venom has been called into question
. As its name might suggest, the recluse is a shy and passive spider that will avoid humans with gusto. Like most spiders, the recluse will attempt to run for cover if threatened and if unable to to escape will begin fast zig-zagging movement to confuse the pursuer. Actual bites are rare and typically only occur in cases where the spider is completely cornered or pressed against the skin, these bites are dry more often than not. Despite these inclinations, these spider are frequently found indoors and therefore do sometimes bite humans who blunder into their hidey-holes. The bites are generally mild however a small percentage result in lesions caused by apparent necrotic properties in the spiders venom, these lesions can become large and cause complications that can damage the nervous system, therefore suspected recluse bites should be watched carefully if you are the unlucky type, but spider bite should not be the front-runner suspect in cases of dermonecrotic lesions as g pyoderma gangrenosum, bacterial infections by Staphylococcus and Streptococcus, herpes, diabetic ulcer, fungal infections, chemical burns, toxicodendron dermatitis, squamous cell carcinoma, localized vasculitis, syphilis, toxic epidermal necrolysis, sporotrichosis, and Lyme disease are some of the things which can be (and very often are) misdiagnosed as a spider bite.
The brown recluse gained the nickname "violin spider" because of the violin looking pattern on the cephalothorax, but this alone is not unique to the recluse and therefore the spider must also possess six eyes arranged in pairs at three seperate points on the head to be properly ID'd.
The hobo spider (Tegenaria agrestis
This lil guy lives in and around my house and is closely related to Tegenaria domestica
and Tegenaria duellica
(the giant house spider, we have those around too). This spider is nicknamed the "Hobo Spider" and has gained an undeserved reputation as a dangerous spider, partly because agrestis
is frequently mistaken to mean "aggressive" while it actually means "of the fields". This misconception has given rise to the nickname "aggressive house spider" despite the fact that T agrestis
is no more ill-tempered than the brown recluse.
Excerpted from wiki excerpted from citations:
"In the United States, the hobo spider has been considered to be a dangerous species based on a toxicology study on rabbits where lesions appeared after spiders were induced to bite the rabbits,. This laboratory study has led to the proposal that in some parts of the U.S. nearly all bites imputed to the brown recluse spider are in reality the hobo spider's bite. The CDC and other U.S. government agencies (e.g. ) have also used this same study as the basis for a report claiming that the hobo spider bite causes necrosis in humans, despite the absence of any confirmed cases. Subsequent attempts to replicate the study by injecting sufficient venom to ensure envenomation have failed to produce necrotic lesions, and there is even question as to whether the lesions observed in the original study were necrotic."
And let me just touch on tarantulas for a moment, despite their fearsome appearance tarantulas are only dangerous to people who are allergic to the small fine hairs they can spray at you in self-defense (think stinging nettles). The venom of tarantulas is weak although the large fangs can deliver a painful physical bite. Tarantulas are an increasingly common pet because of their docile nature (just mind the hairs) although I personally don't like them because I love anoles and no invertebrate should ever eat something with a spine imo.In conclusion
, although spiders with medically significant bites do exist, the fact that there are few of them and the majority are quite docile (unless you live in that hellscape Australia) makes the presence of spiders around the home and garden overwhelmingly beneficial, as they prey on unwanted guests while not bothering anybody themselves. Having a large orb-weaver population around your house can also keep the air much clearer of mosquitoes and other flying pests and potential disease vectors, some species of domestic spider will also prey on other spiders that produce unsightly cobwebs or drive them out by out-competing them over shared a shared food supply.
The following are also points of consideration regarding spiders:
* Firstly, it is often the case that a spider bite is "dry" – the skin may be pierced, but little or no venom is injected into the victim. In such an instance, little or none of the spider's dangerous potential for harm is manifested.
* Secondly, there have been reports of spider bites (by spiders considered otherwise harmless) causing allergic reactions in some individuals, up to and including anaphylactic shock, a life-threatening condition (much the same as a sting from an ant, bee, or wasp may produce a harmful effect apart from the toxic quality of its venom).
* Thirdly, many spiders listed as dangerous are seldom encountered, or have dispositions that make them unlikely to bite despite the high toxicity of their venom.
* Finally, little is known about the toxicity of many spiders, due to their infrequent encounters with humans; the list of venomous spiders is limited to those that are linked to medical events in humans or who otherwise have been extensively studied.Phew, now that we've looked critically at these myths surrounding "deadly" spiders, we can move on to the best part. The really interesting spiders that make me wanna be an arachnologist!
Hey! Bagheera kiplingi
is a vegetarian, and it's named after a jungle book character!http://www.zmescience.com/research/studies/first-mainly-vegetarian-spider-found/
The type of plants it enjoys is called Beltian bodies, and it basically represents leaf-tip structures that are produced by acacia. What’s really interesting is that another animal that fancies the same food is the ant. Some ants have an almost symbiotic relationship with the acacia shrubs, living in the hollow spines and eating an amount that also allows the acacia to thrive, and protecting the plants from other invaders. This relationship has been studied and described in numerous studies.Jumping Spiders
*Female Phidippus mystaceus
Jumping spiders book lungs tracheal system are well-developed, as they depend on both systems (bimodal breathing). Oh, did I mention that spiders move their limbs hydraulically by adjusting the pressure of their bodily fluids in limbs? This is how jumpers jump 50 times their own body length.
"Jumping spiders are known for their curiosity. If approached by a human hand, instead of scuttling away to safety as most spiders do, the jumping spider will usually leap and turn to face the hand. Further approach may result in the spider jumping backwards while still eyeing the hand. The tiny creature will even raise its forelimbs and hold its ground. It may even jump on the hand. Because of this contrast to other arachnids, the jumping spider is regarded as inquisitive as it is seemingly interested in whatever approaches it.
This behavior can be explained by the jumping spider's reliance on vision. Unlike many spiders, which use their secondary eyes mainly for navigation, the jumping spider also uses its secondary eyes to detect nearby entities (many other spiders rely instead on hairs for proximity detection). Having ascertained the presence of a nearby entity, jumping spiders will turn to examine it with the more accurate anterior median eyes, with which they identify the interloper as prey, natural phenomenon, possible threat, or potential mate. This leads them to behave in a manner suggestive of curiosity: since they are highly visual creatures that use their anterior median eyes to assess objects of interest, they must, by necessity, bring anything of interest into their visual field."Ladies
*even if you don't watch the whole thing at least skip to 50 seconds in.
Love those little guys, we have these around here:
They are pretty sweet.
I also lurv orb weavers:
We have another variety all over the place where I live, tis the season.
"In 1973, Skylab 3 took two orb-web spiders into space to test their web-spinning capabilities in zero gravity. At first both produced rather sloppy webs, but they adapted quickly."SPIDER SILK aka METAL WEB SHOOTERS ARE BULLSHIT
Human uses for spider silk:
Peasants in the southern Carpathian Mountains used to cut up tubes built by Atypus and cover wounds with the inner lining. It reportedly facilitated healing, and even connected with the skin. This is believed to be due to antiseptic properties of spider silk.
Some fishermen in the Indo-Pacific ocean use the web of Nephila to catch small fish.
The silk of Nephila clavipes has recently been used to help in mammalian neuronal regeneration.
At one time, it was common to use spider silk as a thread for crosshairs in telescopes, microscopes and similar optical instruments.
Due to the difficulties in extracting and processing substantial amounts of spider silk, there is currently only one known cloth made of spider silk. It is a 11-by-4-foot (3.4 by 1.2 m) textile with a golden tint that was made in Madagascar in 2009. It required four years to extract silk from over one million golden orb spiders.
So not practical, but awesome!
Spider silk has a higher tensile strength than steel. but mass production, has always been a problem.
Which is why they isolated the gene and put in in fucking goats!
Spider goats with spider-silk proteins in their milk!MORE ON SPIDER SILK
"he spider's highly sophisticated spinneret is instrumental in organizing the silk proteins into strong domains. Specifically, the spinneret creates a gradient of protein concentration, pH, and pressure, which drive the protein solution through liquid crystalline phase transitions, ultimately generating the required silk structure (which is a mixture of crystalline and amorphous biopolymer regions). Replicating these complex conditions in a lab environment has proved difficult. Nexia used wet spinning and squeezed the silk protein solution through small extrusion holes in order to simulate the behavior of the spinneret, but this has so far not been sufficient to replicate the exact properties of the native spider silk."Lets all talk about spiders!Edit: clock spider!
This is a huntsman spider, it has very mild venom and is a good thing to have around the house since it tends to hide and feeds on pest insects. So even if you have no pest insects, the spider won't bother you anyway.
Huntsmans are rad.