What kind of spider is this?

What kind of spider is this?

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Found in my house in a Beltsville Maryland

I'm 90-95% certain that the spider in question is a Trachelas tranquillus, more commonly known as a "Broad-faced Sac Spider".

Broad-faced sac spiders are quite distinct in coloring; they have a dark gray/brown head (cephalothorax) with tan/light-gray abdomen, orange/red legs, and distinct pincers (which can be seen if you look closely). These spiders are also quite common for your area, and aren't a major threat to humans.

EDIT: I would like to mention that the images I provided (most likely) have enhanced lighting, and/or are much closer to the spider, so the leg color is (expected to be) lighter than what's depicted in your image.

I disagree with Trachelas. Two points stand out for me - the chelicerae are forward-projecting, rather than the flat face of the sac spider; and the rather odd knock-kneed appearance of the front pair of legs is a bit unusual for Trachelas. There is another two-toned, red-and-tan spider that also turns up in houses in the spring and fall - the European import Dysdera crocata aka the Woodlouse Hunter. That's what this is, I believe.

Anyone know what kind of spider is this?

Pro tip: you’re wasting your studying when you scroll through Reddit. Use Netflix instead.

The rare spanish spider, they help you learn Spanish within a week or two max you're pretty lucky to find one.

Haha I was going to say this breed of spider is called araña de álgebra

This is like the Bing version of the duolingo owl

If you eat it alive it will auto translate all Spanish while living inside you, it will make a new home and raise its family within.

The slightly boring yet also helpful super power spider

Noté que eres hispano. @Arachno_cosas responde esas preguntas en Twitter, también advierte si es de importancia médica.

Gracias, trataba de saber que araña era para buscar si es peligrosa o no y evitar que mi mamá la matara

This spider is obviously one of Charlotte’s descendants. Literate spiders are the best sort of spiders.

Poor spider was just trying to flee discriminacíon

This is Called a “huge nope”. Found in almost every place in the world it’s 8 legs make it creepy and “unfuckwitable”. I suggest you remove it from where you live by at least 30 miles and burn down your house to be safe.

This is a jumping spider! More specifically Cosmophasis sp. Very beautiful!

Thanks! And yeah it really is beautiful.

try the iNaturalist app! In case anyone doesn’t decipher what kind this is, the app tells the genus and species of pics people post

Seek also works like iNaturalist! I’ve identified a LOT of plants and stuff that way

[Icius hamatus](http://Just got this Icius hamatus identified by Picture Insect. Check it out.

I haven’t seen anyone else comment this yet- r/whatsthisbug

I think it’s a species from the genus littilius bastardus

Hey, be nice. Jumpers are incredibly docile, curious, and intelligent. They eat other spiders, they’re active hunters that don’t leave webs, and they have free head movement so they can look around independent of their bodies. If you offer your hand it might look up at you and hop on to investigate. They’re basically the dogs of the spider world.


Ballooning is a behaviour in which spiders and some other invertebrates use airborne dispersal to move between locations. [4] [5] A spider (usually limited to individuals of a small species), or spiderling after hatching, [6] will climb as high as it can, stand on raised legs with its abdomen pointed upwards ("tiptoeing"), [7] and then release several silk threads from its spinnerets into the air. These automatically form a triangular shaped parachute [8] which carries the spider away on updrafts of winds where even the slightest of breezes will disperse the arachnid. [7] [8] The Earth's static electric field may also provide lift in windless conditions. [9] Ballooning behavior may be triggered by favorable electric fields. [10] [11]

Many spiders use especially fine silk called gossamer [12] to lift themselves off a surface, and silk also may be used by a windblown spider to anchor itself to stop its journey. [8] The term "gossamer" is used metaphorically for any exceedingly fine thread or fabric. Biologists also apply the term "balloon silk" to the threads that mechanically lift and drag systems. [ further explanation needed ]

It is generally thought that most spiders heavier than 1 mg are unlikely to use ballooning. [13] Because many individuals die during ballooning, it is less likely that adults will balloon compared to spiderlings. However, adult females of several social Stegodyphus species (S. dumicola and S. mimosarum) weighing more than 100 mg and with a body size of up to 14 millimetres (0.55 in) have been observed ballooning using rising thermals on hot days without wind. These spiders use tens to hundreds of silk strands, which form a triangular sheet with a length and width of about 1 metre (39 in). [8]

In Australia, in 2012 and in May 2015, millions of spiders were reported to have ballooned into the air, making the ground where they landed seem snow-covered with their silk. [14]

Most ballooning journeys end after just a few meters of travel, although depending on the spider's mass and posture, [15] a spider might be taken up into a jet stream. The trajectory further depends on the convection air currents and the drag of the silk and parachute to float and travel high up into the upper atmosphere. [16]

Many sailors have reported spiders being caught in their ship's sails over 1,600 kilometres (990 mi) [17] from land (Heimer 1988). They have even been detected in atmospheric data balloons collecting air samples at slightly less than 5 kilometres (16,000 ft) above sea level. [18] Evidently, ballooning is the most common way for spiders to invade isolated islands and mountaintops. [17] [19] Spiderlings are known to survive without food while travelling in air currents of jet streams for 25 days or longer. [5]

Some mites and some caterpillars also use silk to disperse through the air. [ citation needed ]

A close association has been found between ballooning behaviors and the ability for a species of spiders to survive afloat on water. Water-repellent legs keep them alive on both fresh and salt water, enabling them to survive waves up to 0.5 metres in height. In wind many species raised their legs or abdomens to use as sails, propelling themselves across the water's surface. Many species of spiders also drop silk to anchor themselves in place while afloat. Said spiders did not show these behaviours on land, suggesting that they are adaptations to water. [20] [21] [22]

More about Spiders

The diverse webs spun by spiders provide a remarkable example of the evolution of instinctive behavior. A spider does not have to learn how to make a web, although the spinning itself can be adapted to unique circumstances, including the webs spun by spiders under zero gravitation in spacecraft. The simplest webs are irregular and generally laid out along the ground. More advanced webs, particularly of orb-weaver spiders, are highly intricate, raised above the ground, and oriented to intercept the paths of flying insects. The spinning itself is a complex process involving the placement and then removal of scaffolding spirals and a combination of sticky and nonsticky strands. In some cases a number of spiders will form a kind of communal web, but spiders in general are not social. Such spiders rely largely on the sense of touch.

Photo by:
P. & W. Ward/Oxford Scientific Films

Spiders have separate sexes, and the eggs have to be fertilized. The genital openings of both male and female are located on the abdomen. The male's copulatory organs, however, are complicated structures located on his pedipalps. He spins a little web and deposits sperm in it, then moves the sperm to the palpal organ. After sperm are transferred to the female, they can be stored in her body for an extended period.

Courtship behavior is often complicated. Males may use draglines to detect and recognize mates, or they may signal their approach by plucking on the female's web. In spiders with well-developed eyes, complex mating displays have evolved that are associated with bright color patterns. Often the male must avoid having the female treat it as food even in species where this is common, however, the male often escapes.

Spider eggs are protected in cocoons. The female may guard the cocoons or carry them about. In some spiders the hatchlings remain with the mother for an extended period and may be carried on its body.

As predators on insects and other small animals, spiders are generally highly beneficial to humans, although some feed on important plant pollinators such as bees. They also serve as food for other animals, most notably for certain wasps that paralyze the spiders and lay eggs to hatch on the paralyzed body. Efforts to utilize spider silk for cloth have not been successful economically, but the silk has been used for the cross hairs of optical instruments. Although spiders have occupied an honored place in various mythologies, their widespread unsavory reputation in modern times probably results from their tendency to lurk in dark places, their often grotesque appearance, and a gross exaggeration of their toxicity.

Scientific classification: Spiders make up the order Araneae in the class Arachnida. About 105 families of spiders are known, plus about 10 that are extinct. Two suborders are widely but not universally recognized. The suborder Mesothelae contains a few primitive, burrowing forms. The suborder Opisthothelae contains the infraorder Mygalomorphae, which consists of the "straight-jawed" forms, usually large, such as the trap-door spiders and the ones called tarantula in the United States, and the infraorder Araneomorphae, the members of which have the chelicerae somewhat modified and more efficient it contains the more common and conspicuous forms, such as orb weavers, wolf spiders, and jumping spiders. The cribellate araneomorphs have a specialized organ, the cribellum, that helps to produce silk.

Circulation of Blood in Spiders

Many people assume that spiders have closed blood circulation and respiratory systems not much different from that of humans except perhaps in size. As the following paragraphs will show, this assumption is largely invalid but there are many parallels between the apparatus used by spiders and the equivalent human cardiopulmonary apparatus. It should also be noted that the circulatory and respiratory systems of only a few spider species have been studied so far so what is stated below may not be entirely true for every species.

What kind of circulatory structures are found in the bodies of spiders?
In mammals the circulatory system is an entirely closed double circuit, blood flowing in an alternating fashion first through the blood vessels of the lungs and then through the larger vascular network that supplies the rest of the body. The mammalian heart is actually a double pump that ensures that blood normally does not accumulate in either the lungs or the rest of the body but perfuses all tissues to the extent necessary to keep them alive and functioning normally at a constant body temperature. Spiders have a very different vascular system. Firstly, it is an open network which means its arteries carry haemolymph, the arthropod equivalent of mammalian blood, out into the tissue spaces where it diffuses past individual cells before being collected back into the heart. There are few, if any, veins in this system and definitely no capillaries.

The spider heart is actually a simple, moderately muscular tube located not in the cephalothorax but just under the upper surface of the abdomen and running along the midline. It can actually be seen in many species that have a pale coloured abdominal cuticle. A thin membrane which is the equivalent of the mammalian pericardium encloses it. The heart pumps much of its haemolymph forward through the pedicel and into the cephalothorax using a large artery that some authors refer to as the anterior aorta. There is also the equivalent of a posterior aorta that delivers oxygenated haemolymph to those abdominal organs that need it. To ensure one-way fluid flow a simple valve may be present at the beginning of each of these major arteries. In those spiders that have been studied so far the heart rate seems to be somewhere in the range 30 - 200 beats per minute, depending on the species involved and on the extent to which it is active.

Return of haemolymph to the heart mostly is by simple negative pressure as the heart relaxes between beats. However, haemolymph that has been pumped into the cephalothorax is believed to be driven back through special channels in the pedicel when the pressure in the cephalothorax is higher than that in the abdomen and this fluid then collects in spaces called lacunae before perfusing the many lamellae (individual leaves) of the book lungs and being drawn up through the tissue spaces to the heart, which it enters through a number of small holes called ostia. This secondary pumping action is appropriate in that there are muscles in the cephalothorax that compress and expand it during leg movements.

Each compression of the cephalothorax will therefore drive oxygen-depleted haemolymph backwards through the pedicle and into the gas exchange areas of the book lungs before returning it to the heart. It is a curious fact that vigorous leg activities tend to cause slowing of the heart rather than an increased heart rate and the proposed explanation for this is that increases in haemolymph pressures within the cephalothorax cause a greater flow of fluid back into the abdomen and inhibit the flow from abdomen to cephalothorax via the anterior aorta. The heart then compensates for these changed pressure gradients by slowing down. As is explained below there is evidence that tarantulas possess a cardioregulatory area in the spider brain that may help regulate these heart rate changes.

What are the major components of spider haemolymph?
Spider 'blood' is just as different from its mammalian equivalent as the circulatory apparatus is. A more correct name for it is haemolymph because it has many features in common with the lymph that diffuses through human tissue spaces before being returned to the circulatory system. It is not red because it does not contain the oxygen-carrying pigment, haemoglobin. Instead, it is a pale blue colour due to the presence in it of haemocyanin, an oxygen-carrying molecule that is blue because it contains copper rather than iron as found in haemoglobin. Both are proteins but haemoblobin is packed into cells called erythrocytes whereas haemocyanin is simply dissolved in the haemolymph despite its large molecular size (1,700,000 daltons compared with 66,000 daltons for haemoglobin). In addition, haemoglobin can carry about 17 times as much oxygen as haemocyanin. The haemolymph of a typical spider also contains some cells but it is much less cellular than human blood, which is about 45 percent cells by volume.

So what role do the cells in haemolymph play if they are not for carrying oxygen around the spider's body? Well, the available evidence indicates that some of them help minimize bleeding from small injuries such as a lost leg and thereby also promote healing. In this respect they probably work in a manner similar to that of the platelets in our blood or the thrombocytes of vertebrates other than mammals. It is for this reason spiders can lose a leg or two without dying, although damage to the more fragile abdomen is almost always rapidly lethal.

But in spiders the cells of haemolymph do more than just inhibit its loss at injury sites. Although the histology of the blood of only a very few spider species has been studied so far, there has been a considerable amount of research on the blood of insects and crustaceans and the available data suggests the blood cells of all of the major arthropod classes do much the same things. The main production site for haemolymph cells seems to be the walls of the spider's heart where there are cells called prohaemocytes. These are the equivalent of the stem cells of the human bone marrow. However, as is true for our primitive bone marrow cells, very few prohaemocytes are present in haemolymph. Instead, they mostly transform into one of at least three different mature cell types before entering the circulation.

The stained appearance of these mature haemolymph cells and their similarities with human blood cells are presnted in the next graphic. The least numerous of these cells are cyanocytes which make haemocyanin and release it into the circulating fluid. Plasmatocytes are the cell type present in the greatest numbers but there are also many granulocytes in haemolymph. Both are said to function as phagocytes, removing pathogens and tissue fragments from injury sites but it is now accepted that plasmatocytes also cause the 'clotting' of haemolymph by a platelet-like action and perhaps also by the release of clotting factors (the biochemical processes involved in haemolymph clotting are still poorly understood). Granulocytes have an even greater phagocytic role and also are believed to release antimicrobial peptides such as gomesin. These peptides presumably serve the same role as the antibodies (immunoglobulins) of mammalian blood but there are no spider cells equivalent to the lymphoid cells of humans. It is also a curious fact that spiders have an innate 'immune' system which can be effective in just a couple of hours of exposure to a pathogen. Also significant is that the response is quite broad, unlike the mammalian immune response which is much more specific but also much slower to develop.

What anatomical structures do spiders use to accumulate oxygen?
Mammals obtain oxygen from the surrounding air by placing blood cells in very close proximity to air that has been drawn into and out of the lungs in a cyclic fashion. This provides a very large gas exchange area so oxygen can enter the blood efficiently and carbon dioxide can leave it with equal ease. While spiders have relatively less need for oxygen than warm-blooded mammals, they cannot survive indefinitely without it and are also first anaesthetized and eventually killed by high concentrations of carbon dioxide. Spiders do not have sponge-like lungs but instead make use of one or two pairs of book lungs which have a close resemblance to the gills of fish.

There is no cyclic movement of air over the individual 'leaves' (lamellae) of the book lungs but there are many of these in each book lung and they are well perfused by haemolymph so the total area for exchange of oxygen and carbon dioxide is quite large. In those species that have only one pair of book lungs the second pair are believed to have gradually changed into a system of fine tubes called tracheae, these having similarities with the trachea and bronchial system of the human lungs although they are kept open by chitin rather than by cartilage as in mammals. They only have one or two openings called spiracles, these being located on the underside of the abdomen between the spinnerets and the book lungs. Although the air in the tracheal system of spiders is not exchanged in a cyclic fashion there may be some incidental replacement of the tracheal air by other movements the spider makes.

What advantages do tracheae have over book lungs? The answer to this question varies with the size, behaviour and habitat of each spider species. Tracheae allow better direction of oxygenated haemolymph to those structures that need it most. Hence, tracheae that extend forwards through the pedicel provide an efficient oxygen supply for the spider brain and those species that have them in the cephalothorax tend to have significantly reduced maximum heart rates. Surprisingly, it appears that not more than ten percent of a spider's tracheal tubes are in the cephalothorax and they do not penetrate the muscles that allow cyclic compression of it although in web-monitoring spiders such as the uloborids they do enter the first segments of the legs. There are two other advantages that tracheoles have over book lungs: they are better for water conservation in spiders such as the salticids that are active during the daylight hours, and they also can store a small but significant amount of air when the spiracles are closed.

To what extent are breathing and the circulation of blood under the control of a spider's nervous system?
Comparatively little research appears to have been done on the circulation of blood in a spider and even less on the regulation of gas exchange within its respiratory apparatus. There is no convincing evidence that air flow in either the book lungs or the tracheae is regulated by deliberate neuromuscular activity but some passive air exchange undoubtedly does occur and the spider may be able to vary the amount of haemolymph perfusing them when necessary. On the other hand, there is research data that suggests there is a circulatory centre within the brain, at least in tarantulas. This centre exerts neural control over a cardiac ganglion located in the first segment of the spider heart. Stimulation of the nerves to this ganglion sometimes leads to either an increase or a decrease in heart rate, suggesting the circulatory centre may have both cardioaccerator and cardioinhibitor areas.

Some related sources of information
The pages on spider movements, growth and reproduction, and silk production contain some information that is related to what is covered in the above paragraphs. In addition, the following articles are worth reading:

Kuhn-Nentwig L and Nentwig W. (2013) "The Immune System of Spiders" pages 81-92 of Spider Ecophysiology Editor W. Nentwig, Springer-Verlag Berlin ISBN: 978-3-642-33985-2

Spider Anatomy

External Structure

Unlike other insects, the most populous type of arthropods – spiders have bodies divided into two segments or tagmata (singular: tagma). These are the cephalothorax, formed by a fusion of the head and thorax (cephalon means head/brain), and the abdomen. These are also called prosoma (front body) and opisthosoma (rear body), respectively. The two tagmata are connected by a thin waist-like structure called pedicel. The pedicel joint allows the spider to move the abdomen without moving the cephalothorax. This is useful especially when spinning webs, when the abdomen needs to move according to the pattern of the web, but the cephalothorax has to remain stationary.

Spiders’ legs, chelicerae, eyes, mandible, claws, etc., are all attached to the cephalothorax, whereas, the abdomen contains most of their internal organs.

Spider eyes are a combination of the compound eyes seen in insects, and the single-lens eyes seen in higher organisms. Spiders have multiple – usually 8 – single eyes, but the configuration of the eyes differs according to the habitat and diet of the particular species. Some spiders even have 6, 4, or 2 eyes.

Some species, especially those specialized to living in caves, lack eyes entirely, since they are useless in their dark environment.

Vision is rarely the primary sensory tool in spiders (the hair on their legs are their crucial sensory organs), but hunting spiders such as jumping spiders and wolf spiders have extremely well-developed vision, and some even have color vision. These spiders don’t weave silk webs, but actively pursue prey by ambushing or chasing them.


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Chelicerae are the mouth parts of spiders, and are also used in most species to inject venom into their victims. Spiders can’t chew their food, and instead suck their food after starting the digestion process outside their body. The fangs are found on the extremity of chelicerae, and are connected to the venom glands, situated behind the chelicerae.

Digestive System

Spiders can’t chew and can only drink semisolid, mashed food. They either use their chelicerae to tenderize their prey, or, in case of spiders with weaker chelicerae, spew digestive juices onto the food, starting the digestion process outside the body. They then proceed to suck up the mashed food. The sucking stomach, which is a muscular pump with valves to ensure one-way movement of the food, lies in the cephalothorax, and leads to the mid-gut, or the intestine. The intestine extends into the abdomen, and gives rise to diverticula. The intestine culminates in the stercoral pocket, which is analogous to the rectum, and the anus.

Circulatory System

Unlike higher organisms, spiders don’t have a network of blood vessels, but possess an open circulatory system. Instead of interconnected mazes of arteries, capillaries, and veins, a spider’s heart pumps blood into the arteries, which deliver the blood in sinuses surrounding internal organs. The blood in arthropods is known as hemolymph, and spider blood is called hemocyanin. It contains copper, and is thus tinted slightly blue.

The heart is situated in the upper abdomen, and is covered by a thin covering known as pericardium. The aorta extends into the prosoma through the pedicel, while several smaller arteries feed the abdomen.

Respiratory System

Different species of spiders have variations in the particular method of respiration, but like all arthropods, spiders don’t have a ‘nose’, and breathe trough diffusion of oxygen into the blood in their breathing organ. Many spiders have book lungs, an organ with alternating layers of sinus and tissues, that allow for the diffusion of oxygen into the hemolymph. Some spiders have developed tracheal systems similar to those seen in many insects. Tracheal systems are more efficient than book lungs, and allows the spider to be more active. Hunting spiders such as jumping spiders and wolf spiders usually have tracheal systems that allow them to actively pursue their prey. Some spiders that live in moist, hydrated habitats, don’t have a specialized respiratory organ, since the diffusion of oxygen through their skin alone is sufficient for their survival. The respiratory organs are situated in the lower abdomen, usually near the pedicel.

Nervous System

Their brains are composed of three main parts – the cheliceral ganglion, subesophageal ganglion, and the brain. The subesophageal ganglion is situated, as the name suggests, below the esophagus, and the brain lies next to the cheliceral ganglion. The brain and the cheliceral ganglion are together called the supraesophageal ganglion, and are located above the subesophageal ganglion, and thus the esophagus. The cheliceral ganglion controls the chelicerae and the venom glands, and the brain is primarily tasked with vision. The nerves that control the abdomen, the cauda equina, originate in the subesophageal ganglion. The sub and supraesophageal ganglions make up the central nervous system of spiders.

Reproductive System

Most spiders reproduce sexually, and have well-developed sexual organs. Male spiders produce semen, and hold it in their pedipalps until they find a female. The semen is inserted into the female through her epigyne. Cannibalism among spiders after copulation is a well-documented phenomenon. Female spiders are larger than males, and can mistake potential mates for a potential meal.


Spinnerets are responsible for the production of spider silk, and are located in the abdomen, below the gonads. The spinnerets produce silk, which is then woven using specialized hair on the fourth pair of legs. Most spiders build webs, but many have evolved to become active hunters. The spinnerets on these spiders are either reduced or poorly developed.

Spider anatomy is a weird mixture of primitive and advanced characteristics. If you are not scared of them, spiders are one of the most interesting and bewildering creatures in the world.

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Spider Myths

As the only spider specialist in a large metropolitan area, I get many spider inquiries from the general public. Since I'm mentioned on the Internet as a spider specialist, some of the public inquiries come from distant places. When I lecture on spiders, adult and child audiences always have questions and comments. So do casual acquaintances when they learn that I work with spiders.

These people's concerns come from a widespread and surprisingly uniform set of assumptions and "general knowledge" about spiders. And almost all of this widespread spider information is false!

I don't really expect that the following, by itself, will make much headway against the flood of spider misinformation. However, I hope that those curious about spiders who find their way here will absorb enough information to ask me some new questions instead of the same old ones. I can hope, can't I?

Questions and Comments. For general spider information go to our resources page . To suggest improvements or additions, or to ask a question, please contact me . But if you hope to show that any of the following myths is actually true, please be prepared with verifiable evidence including actual specimens…

Spider facts

Some commonly asked questions and interesting facts about spiders.

Are huntsman spiders dangerous? They look so large and hairy.

Despite their often large and hairy appearance, huntsman spiders are not considered to be dangerous spiders. As with most spiders, they do possess venom, and a bite may cause some ill effects. However, they are quite reluctant to bite, and will usually try to run away rather than be aggressive. In houses they perform a useful role as natural pest controllers.

Some people may think of huntsman spiders as 'tarantulas'. However, they are not related to the large hairy ground dwelling spiders that are normally called tarantulas. Both huntsman spiders and tarantulas are often portrayed as being dangerous and scary. This usually is the case in films or stories that deliberately present spiders in a frightening and unrealistic way. If you feel frightened of huntsman spiders because of this, perhaps you might like to learn more about their true habits and biology. In this way you might be able to reduce your fears.

Toggle Caption

How do you identify a wolf spider?

One of the diagnostic features of wolf spiders is their eye pattern which comprises three rows at the front of the carapace: four (smaller) eyes in the first row, two above the first and two above the second row. The diagram below (basically) shows this layout, face-on to the spider:

Wolf spiders also have a variegated pattern on their bodies, often including radiating lines on the carapace and scroll-like patterns on the top of the abdomen. The underside of the spider is grey or black, sometimes with white markings. They can have orange spots on the sides of their jaws.

As wolf spiders actively hunt for food they are likely to be found roving along the ground and they are more active at night. When spotlighted at night wolf spider's eyes will glow green. Scientists use this method during invertebrate surveys.

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Does Australia have a bird-eating spider?

The term ɻird-eating spider' usually refers to large spiders from the family Theraphosidae. These spiders are also referred to as tarantulas. In Australia the theraphosids are represented by the whistling spiders (Selenocosmia sp.). These ground-dwelling spiders are big enough to prey on small frogs and reptiles, but are not known to eat birds. They are also known as barking spiders.

Do we have tarantulas in Australia?

It depends on what you mean by the word "tarantula". Some people use it to describe the large hairy spiders of South and Central America. In Australia, the whistling spiders are also called Australian tarantulas, as they are related to the American spiders. However, the word tarantula is also used to refer to huntsman spiders.

Tarantula is derived from the name of a town in Italy, Taranto. This town is the original home of the wild dance called the tarentella. During the Middle Ages, the tarentella was thought to be the way to cure the bite of a particular spider. The symptoms - known as tarantism - included severe pain, swelling, spasms, nausea and vomiting, palpitations, and fainting, along with exhibitionism, melancholia and delirium. It was hard to determine whether an actual bite had occurred or if people were merely displaying some form of madness or hysteria. Scientists later determined that many cases might indeed have been the result of a bite, although much of the fierce dancing and extreme behaviour may reflect more about the social and sexual repression at the time.

The alleged spider that caused all of these symptoms was called a tarantula, but the species was incorrectly identified. The original spider identified by the people of the time was a wolf spider (Lycosa tarantula). However, it was subsequently shown to cause little serious results when it bit people. Finally, it was shown that the real culprit was a Black Widow relative, Latrodectus tredecimguttatus, known in Southern Europe as the "malmignatte". The symptoms of this spider's bite (and of other Latrodectus species, including the Redback Spider) match the whole-body symptoms experienced during tarantism.

Information from: Hillyard, P. 1994. The Book of the Spider. Hutchinson, London.

Do we have scorpions in Australia?

Yes we do. Scorpions are common in gardens and forests throughout eastern Australia and are found under logs, rocks and in shallow burrows in earth banks. They are nocturnal - which is why we rarely see them - but they can be disturbed during the day, especially during the prolonged wet weather. There are also species that live in the desert and others that inhabit tropical rainforests.

What is the world's most dangerous spider?

It is hard to define which spider in the world is the most dangerous to humans. Several spiders could qualify, depending on what you mean by dangerous. Do you mean the spider with the most toxic venom, measured by its effect on newborn mice or other mammals? Or do you mean the spider that has caused the death of the most people? Those that have the strongest venom may not be encountered by humans very often, or may even have trouble piercing human skin and so are not considered to be ⟚ngerous'. Data are usually only kept on bites from spiders that are potentially deadly or cause severe reactions and these data are not recorded consistently at a national or international level. Here, we will define dangerous as �ly'.

In summary, on current evidence the most dangerous spiders in the world are funnel-web spiders (Atrax and Hadronyche species), Redback Spiders and their relations (Latrodectus species), Banana Spiders (Phoneutria species) and Recluse Spiders (Loxosceles species). In Australia, only male Sydney Funnel Web Spiders and Redback Spiders have caused human deaths, but none have occurred since antivenoms were made available in 1981.

The Australian funnel-web spiders are among the deadliest spiders in the world in the effect their bites have on humans and our primate relations (although the bite has little effect on dogs and cats). There are many species of funnel-web spiders in Australia but only male Sydney Funnel-webs have caused human deaths. There have been only 13 deaths recorded from male Sydney Funnel-webs, but up to 30-40 people are bitten by funnel-web spiders each year. Mouse spiders may have venom that is as toxic as that of some funnel-webs, as some patients have had severe reactions to their bites, although no-one has been recorded as having died from the effects of a mouse spider bite. Antivenoms are available for both funnel-web and Redback Spider bites.

A group of spiders that is dangerous in many countries belongs to the genus Latrodectus in the Family Theridiidae. In Australia we have the Redback Spider (Latrodectus hasselti). In America, a common representative of this genus is the Black Widow (Latrodectus mactans). Antivenoms are available for both funnel-web and Redback Spider bites.

A deadly spider which comes from South America is the Banana Spider, Phoneutria species. In south-eastern Brazil between 1970 and 1980, more than 7,000 people were admitted to hospital with bites from this spider. An antivenom also exists for this species.

The Recluse or Fiddleback Spider is a deadly spider belonging to the genus Loxosceles. Recluse spiders are found in many parts of the world and have been introduced into Australia. The venom of this spider can cause severe skin necrosis (eating away of the flesh) and can be fatal although not many deaths have been recorded.

How many dangerous spider bites occur in Australia each year? Has anyone died from a bite recently?

There have been no deaths in Australia from a confirmed spider bite since 1979. An effective antivenom for Redback Spiders was introduced in 1956, and one for funnel-web spiders in 1980. These are the only two spiders that have caused deaths in Australia in the past.

A spider bite is not a notifiable medical emergency, so there are no Australia-wide statistics, but the following figures give an idea of the incidence of reported bites in recent years.

Approximately 2000 people are bitten each year by Redback Spiders

Funnel-web spider antivenom has been given to at least 100 patients since 1980. Antivenom is given only when signs of serious envenomation are observed. Many spider bites are ɻlank', which means that no venom has been injected.

During 2000 the New South Wales Poisons Information Centre received 4,200 calls about spiders. However not all of these would have involved actual bites. Many reported bites are not able to be identified as definitely being from a spider, and it is nearly impossible to work out what species has caused a bite without seeing a specimen of the spider responsible.

Figures are from: Sutherland, S K and Nolch, G (2000) Dangerous Australian Animals. Hyland House, Flemington, Vic. 201 pp. ISBN 86447 076 3

  • Poisons Information Centre
  • The Children's Hospital at Westmead
  • Locked Bag 4001
  • Westmead, NSW 2145
  • Emergency telephone: 131 126 (24 hours, within Australia only)
  • Administrative telephone: +61 2 9845 3111
  • Fax: +61 2 9845 3597

What spiders in Australia may cause ill effects if they bite you?

In Australia, bites from at least two kinds of spiders - wolf spiders and white-tailed spiders - in some cases cause skin necrosis (eating away of the flesh). However, neither spider has caused human deaths. There are also a number of others which are thought to cause the same problem, but research is still being done to find out exactly which species do so.

Bites from many Australian spiders can cause localised reactions, with symptoms such as swelling and local pain at the site of the bite, sweating, nausea and vomiting and headaches. All of these symptoms will vary in severity depending on the age of the victim, their health, and the amount of venom that the spider was able to inject. Have a look at our spider fact sheets to find out more about individual species.

Do white-tailed spiders cause the skin condition known as necrotising arachnidism?

There is an ongoing debate among toxicologists and spider biologists about the effects and dangers of white-tailed spider bites. Most of these bites appear to cause little or no effect beyond transient local pain. However a small number of cases do cause more extensive problems. Whether this is a result of the spiders' venom or to bacteria infecting the wound at or after the time of the bite has not yet been resolved. It is also possible that some people may react badly to white-tailed spider bite, possibly because of immune system susceptibility or a predisposing medical condition.

  • Meier, J. & White, J. (1995) Handbook of Clinical Toxicology. CRC Press, Florida USA.
  • Whitehouse, R. (ed.) (1991) Australia's Dangerous Creatures, Readers Digest Pty Ltd, Surry Hills NSW.
  • Sutherland, S. & Sutherland, J. (1999) Venomous Creatures of Australia, Oxford University Press, South Melbourne.
  • Isbister,G. & Greay,M. (2000). "Acute and recurrent skin ulceration after spider bite" Medical Journal of Australia 172, 20 March 2000, pp.303-304

How do I control white-tailed spiders around the house?

Beyond killing or removing all white-tailed spiders that you encounter, you can try a prey reduction strategy. White-tailed spiders like to feed on Black House Spiders (Badumna insignis) in particular, but will take other spiders too. This means that you should clean up obvious spiders around the house (outside and in). This involves removing spiders from around windows, walls and verandas (by web removal and/or direct pyrethrum spray). The condition of the roof cavity and the underfloor area (if raised) should also be investigated. (from Mike Gray, Arachnologist, Australian Museum)

What is the biggest spider in the world?

The biggest spider in the world is the Goliath Spider, Theraphosa leblondi. It lives in coastal rainforests in northern South America. Its body can grow to 9 cm in length (3.5 inches) and its leg span can be up to 28 cm (11 inches). (from: Carwardine, M. 1995. The Guinness Book of Animal Records. Guinness Publishing.)

What is the biggest spider in Australia?

Australia's biggest spiders belong to the same family as the Goliath Spider. They are the whistling spiders. The northern species Selenocosmia crassipes can grow to 6 cm in body length with a leg span of 16 cm.

What is a Daddy-long-legs?

�y-long-legs' is the common name for a particular group of spiders, but it is also used for a different group of arachnids - the harvestmen or opilionids. As a result, there is a lot of confusion about what people mean when they say �y-long-legs'.

The animal which most biologists call Daddy-long-legs, is a spider, Pholcus phalangioides, which belongs to the spider family Pholcidae, order Araneida, class Arachnida. It has two parts to the body, separated by a narrow waist. It has eight eyes and eight very long thin legs. Pholcids often live in webs in the corners of houses, sometimes in bathrooms. Daddy-long-legs spiders (or pholcids) kill their prey using venom injected through fangs. Digestion is external, with fluids being squirted onto the prey item and the resulting juices sucked up by the spider.

The other eight-legged invertebrates that are sometimes called Daddy-long-legs, are members of the order Opiliones or Opilionida in the class Arachnida. Another common name for these arachnids is 'harvestmen'. Unlike spiders, their bodies do not have a 'waist', they do not produce silk and they normally have only one pair of eyes. They do not have venom glands or fangs, although they may produce noxious defence secretions. Most harvestmen eat smaller invertebrates but some eat fungi or plant material and others feed on carcasses of dead mammals and birds. Digestion is internal and some solid food is taken in, which is uncharacteristic for arachnids. You usually do not find harvestmen inside houses.

Are Daddy-long-legs the most venomous spiders in the world?

There is no evidence in the scientific literature to suggest that Daddy-long-legs spiders are dangerously venomous. Daddy-long-legs have venom glands and fangs but their fangs are very small. The jaw bases are fused together, giving the fangs a narrow gape that would make attempts to bite through human skin ineffective.

However, Daddy-long-legs Spiders can kill and eat other spiders, including Redback Spiders whose venom can be fatal to humans. Perhaps this is the origin of the rumour that Daddy-long-legs are the most venomous spiders in the world. The argument is sometimes put that if they can kill a deadly spider they must be even more deadly themselves. However this is not correct. Behavioural and structural characteristics, such as silk wrapping of prey using their long legs, are very important in the Daddy-long-legs' ability to immobilise and kill Redbacks. Also, the effect of the Daddy-long-legs' venom on spider or insect prey has little bearing on its effect in humans.

What are banana spiders and where are they found?

Banana spider is the common name given to large (3 cm body length) active hunting spiders of the genus Phoneutria (Family: Ctenidae). These spiders live in Central and South American rainforests. They are often found in rubbish around human dwellings, as well as hiding in foliage such as banana leaves where they sometimes bite workers harvesting bananas. They have a reputation for being quite aggressive.

Other names for this spider include: Kammspinne, Bananenspinne, Wandering spider, and Aranha armadeira.

The venom of this spider is neurotoxic - acting on the nervous system - and causes little skin damage. Symptoms of a bite include immediate pain, cold sweat, salivation, priapism, cardiac perturbations and occasional death. Research suggests it is similar in action to a-latrotoxin, which is produced by spiders of the Family Latrodectidae, such as the Redback and Black Widow Spiders.

Another spider that seems to have been given the common name "banana spider" is actually a completely unrelated species of orb weaving spider from Florida. This is a good example of why it is more useful to use scientific names when you are trying to find information on different animals or plants.

How do I find out about spiders in New Zealand?

The following New Zealand arachnologist (spider biologist) has offered to respond to inquiries from people interested in New Zealand spiders:

Dr Phil Sirvid
Entomology Section
Museum of New Zealand Te Papa Tongarewa
PO Box 467
Wellington, New Zealand
ph: +644 381 7362
fax: +644 381 7310

There is a book on New Zealand spiders: Forster, Ray and Lyn. 1999. Spiders of New Zealand and Their Worldwide Kin. University of Otago Press, ISBN 1 877133 79 5

What about white-tailed spiders in New Zealand?

Dr Phil Sirvid has this to say about white-tailed spiders in New Zealand:

"We have two species of white-tails in New Zealand - Lampona cylindrata and Lampona murina. They are both very similar in appearance, and can really only be separated from one another by viewing them under a microscope and examining certain features that aren't apparent to the naked eye.

Both have been introduced from Australia.

L. murina has been in the North Island of New Zealand for [over] 100 years, and has also been introduced to the Kermadecs, Lord Howe Island and Norfolk Island. I wouldn't be surprised if it's in the Chatham Islands as well. In Australia, this species is recorded along the East Coast from northern Queensland down through New South Wales and Victoria.

L. cylindrata had only been found occasionally in the South Island until the 1980s. About this time it seemed to spread rapidly throughout the South Island's main urban centres, and is known to occur as far south as Dunedin. This species is found along the southern part of Australia from Western Australia, through South Australia, Victoria and Tasmania, as well as in New South Wales and Queensland."

How can I find out about spiders in North, South or Central America?

We do not have a scientist at the Australian Museum who is an expert on the spiders of the Americas. However you could look at some US spider web sites to see if they can help you. Or you could contact an American spider expert.

Spider biology facts

What is the function and origin of silk glands and spinnerets in spiders?

The development of spinnerets and silk represents a major evolutionary shift that has defined the biological and ecological uniqueness of spiders within the arachnids. Silk glands produce the silk that the spider uses for a variety of purposes. The spinnerets are the special organs that the spider uses to extract and manipulate the silk as is it is produced from the silk glands.

Spiders evolved from ancestors that had limbs on the abdomen, as did arthropods like crustaceans such as crayfish. In fact, one of their few living marine relatives, Limulus, the so-called 'king crabs', has retained abdominal limbs, which have been lost or greatly modified in terrestrial spiders and other arachnids. The spiders' spinnerets are almost certainly derived from these ancestral abdominal limbs. In the basal (lowest) segments of spiders' limbs are small excretory glands - the coxal glands - that secrete and excrete waste body fluids. It seems that the silk glands may represent highly modified excretory glands that now manufacture silk instead of waste products, just as the spinnerets represent highly modified limbs.

It is possible that an intermediate stage in this process could have been the production of a secretion that included pheromone (scent) chemicals put out by the spider as a primitive 'signal line' by which a spider could find its way back to its retreat burrow. This role was then taken over by the production of silk. The silk then became useful not only as a safety line, but also for prey capture, manufacturing egg sacs and a host of other activities.

[Modified from text by Dr Mike Gray - Principal Research Scientist (Spiders)]

Reference: Foelix, R.F.1996. Biology of Spiders. Oxford Thieme.

Why don't spiders get stuck to their webs like the insects that they catch?

If you look at an orb-weaving spider in its web, you'll notice that the body is held slightly clear of the web, especially when the spider is moving about. The spider has only minimal (but vital) body contact with its web via the claws and bristles at the tip of each leg. Compared to its prey, which crashes or blunders into the web, the spider has only a tiny portion of its surface area in contact with a very small amount of silk at any time. This is obviously an important factor when moving on a sticky web - the less contact the better.

Another important factor is that not all silk lines in a sticky web are sticky. For example, the central part of an orb web (where the spider sits) is made of dry silk, as are the spokes supporting the sticky spiral line, which the spider can use when moving around its web. It's only when the spider makes a quick, direct charge across the sticky spiral to capture prey that it may cause some disruption to the web - but it never gets stuck.

Spiders also spend a lot of time grooming their legs. The spider draws the ends of its legs through its jaws to clean them of debris, which may include silk fragments. This is a very important maintenance activity that contributes to efficient function of the claws and bristles. As well as cleaning them, some secretions from the mouthparts may help make the leg tips less susceptible to sticking.

Why don't orb weavers and other spiders fall off their webs?

Most web-building spiders have three claws on their tarsi (feet) - two combed main claws and a smooth central hook. The web silk is only grasped by the hook, and is pushed against serrated bristles, which snag the silk and hold it. When the hook is released by a special muscle, the elastic silk simply springs away from the hook.

Why can some spiders climb slippery surfaces such as glass or run across ceilings?

Many hunting spiders possess dense hair tufts called scopulae under the claws of their tarsi (feet). These scopulae allow many spiders to walk on smooth vertical surfaces, across ceilings and even window panes. Each individual scopula hair splits into thousands of tiny extensions known as end feet. These end feet increase the number of contact points of the tarsi with the surface, creating great adhesion. This is similar to the adhesion forces at work in vertebrates such as skinks and geckos, which can also walk on ceilings with ease. The scopulae can be erected or laid flat by hydraulic pressure through changes in the pressure of the hemolymph (blood supply).

Do spiders sleep?

It really depends on how you define 'sleep'. All animals have some sort of ɼircadian' rhythm - a daily activity/inactivity pattern. Some are active during the day - diurnal - others are active at night time - nocturnal/crepuscular. The periods of inactivity are characterised by withdrawal (to a shelter perhaps) and a drop in metabolic rate.

This applies to spiders as well, although no studies have been done to measure the period of time spent in such a state or at what times different species do it. It seems that spiders with good eyesight that rely on vision to capture prey may tend to be more active in daylight hours, whereas others that rely on snares/webs could be active at other times, but this is not necessarily the case for all species.

In cold climates, spiders 'overwinter', which means that they have a kind of hibernation period. Overwintering involves a drop in metabolic rate, where the spiders bring their legs into their body and remain huddled in a shelter during the coldest months of the year.

This ability to shut down for a long period of time indicates that they might be able to do it for shorter periods in their everyday cycle, which could be seen as a form of sleep or rest.

Information from: Foelix, R.F. 1996. Biology of Spiders. Oxford Thieme and the Arachnology section, Australian Museum.

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