Venomous Spiders: Are spiders venomous?

We already had enough when we learnt that spiders could listen without an ear and take into the air without flappers. But, that’s actually far from the end for what Mr. creepy spider is really capable of. 

According to one research, all spiders also posses venomous glands which aids in the facilitation of venomous bites. They seem to be the all round package of the animal kingdom don’t they?

In this article, you’ll discover how spider venoms works and what species happen to be the most deadliest of them all.

Are spiders venomous?

Nearly all species of spiders have venom glands which means they are venomous. Regardless of this fact however, very few percentage of them are capable of inflicting toxic bites that can trigger severe reactions in humans. The severity of this reaction of course depends on the species, age and sex of the biting spider and also on the age and current health of the person that is bitten.

Why do spiders produce venom?

Like many venomous arachnids, reptiles and underwater creatures of the animal kingdom, venoms that spiders produce are strictly meant for their feeding.

They inject their preys with neurotoxic venoms after completely wrapping them with silk in order to paralyze or effectively kill them. This makes their dinner very easy to devour at sight or transport to the nest since it prevents them from engaging in any struggle with the prey that could possibly lead to injuries.

The venom gland

The venom gland in spiders is located somewhere within their mouth area and the needle-like fangs they use to inject venoms into preys are located at the front part of the mouth cavity, often retracted.

These fangs have within them a hollow duct that connects directly into the venom bank which acts as narrow pipe for sucking up or bring the venom directly into the tiny opening located at the very tip of the fang. The entire system basically works like a hypodermic needle.

When spiders attack their prey, they wrap them up in silks (not all species do this) and then proceed to swing forth their retracted fangs to pierce through their bodies. Then, they squeeze and force venom out through the tiny opening on the fangs, depositing it into the body of the victim. This effectively paralyses the animal or sometimes kills it instantly. 

Some spiders consume part of their preys by chewing with their serrated teeth located on the chelicerae (or simply mouth area) and then suck up the remains by excreting digestive fluids to liquify it, with the aid of their fangs. Other species simply liquify their prey instead of chewing them.

Spiders can swing their fangs forward like an axe or towards each other like a pincer. Depending on species, age and gender of the spider, venoms may be weak or highly potent when injected into humans.

Venom glands in spiders probably originated as an accessory digestive glands whose secretions aided in the external digestion of prey, as evident in the mode of feeding of many spiders. 

Can spider venom kill humans?

While a majority of spiders are known to produce venoms capable of immobilizing and sometimes killing their preys, these venoms in most cases are simply too weak to cause any adverse reactions in humans.

There are however, some species of spiders like the black widow and the brown recluse spider, that are known to produce toxic venoms capable of exerting severe effects on the nervous system and in extreme cases can lead to respiratory and cardiac arrest.

Most spiders lack the strength in fangs and overall mouth area to be able to inflict bites on humans, and of the species that are able to bite, the bites they administer are usually dry and painful with no venom transferred.

Spiders are wise enough to single out potential prey from an attention seeking human, and therefore know when to use venom and when not to.

Those with impotent venoms that are able to transfer these venoms from a bite, often do so in little quantities that are insufficient to cause any serious or adverse reaction in the bitten party, the side effects mostly suffered are mild pains in the bitten area and inflammation of the region which may cause blisters or lesions.

Symptoms usually subside hours after the bite and individuals usually do not need to seek any medical attention. (Like any other diseases or insect bites however, there are always those individuals that will develop severe reactions that may in some cases lead to premature or sudden death).

For the red marked spiders, those with potent venoms, a single bite from them can trigger serious side effects in the bitten party, often individuals with compromised immune systems, childern, elderly, or those that are allergic to the bite.

The syndromes often suffered include cell and tissue damage which can cause severe skin ulcers and inflammations that can get infected, difficulty in breathing, dizziness, blurred vision and muscle rigidity.

Symptoms can last for as long as five days and victims usually recover with a quick administration of anti-venom. Any unnecessary delay in treatment of bites of this kind can lead to the death of the individual especially if its a child, and elderly person, a perviously sick person or someone that is seriously allergic to spider bite.

Death from spider bites (previous and current records) are very rare, regardless of whether the spider envenoms impotent or potent venom to the party, of specie, and of level of injection. Most victims of severe cases often make it through with just a simple administration of anti-venom.

When do spiders bite?

Like any other species of animals in the wild, an even us humans, spiders dislike being provoked or disturbed unnecessarily.

Most spider will often run away or play dead when you try to reach for them on the ceiling, but some will not hesitate to bite instantly or when cornered. Mother spiders will also not hesitate to charge and bite to protect her eggs.

Most spider bites occur as a result of unintentional contacts or trapping of spiders, for example, when individuals wear cloths or shorts infested with spiders and their bodies or legs begin suffocating or terrify the creatures.

Female spiders often pack more venom and are more defensive compared to their male counterparts. In some species, the females are much more bigger and larger than the males.

What spiders are the most dangerous and where do they live?

Only about a dozen species of spiders out of the possible 40,000 currently discovered pack any venom capable of causing severe illnesses in humans, four of the most dangerous and where they are found include:

  1. Brown recluses spider
  2. Black widow spider
  3. South American wandering spider
  4. Australian funnel-web spider

1) Black widow spider

Are black widow spiders poisonous

A very terrifying creature right from its name, the black window spider has venom that can cause severe neurotoxic effects when administered into the body.

Individuals that suffer the most complications are elderly, children, and those with compromised immune systems.

Their bites usually feels like pin-pricks against the skin and syndromes include severe muscle pain and cramping, nausea, and mild paralysis of the diaphragm which can make breathing difficult.

Symptoms can last for up to 5 days and most people often recover before then with no serious complications at all. Black widow spiders are often found in North America, Latin America and West Indies.

2) Brown recluses spider

Also known as violin spider, brown recluses are one of the most dangerous spiders in the world. Their venoms, when injected into the body at sufficient dose can destroy the walls of the blood vessels surrounding the site of the bite, causing severe skin ulcer.

The wound produced from the bite may take several months to heal, and if not properly treated, can become infected and lead to the victims death. Brown recluses are commonly found in the united states specifically in the southern and western parts.

3) South American wandering spider

Also referred to as banana spider or Brazilian wandering spider, these spiders are one of the most aggressive species of spiders in the world.

They often raise their legs up as a sign of warning when confronted by humans, especially if its a mother protecting her eggs.

Their venoms when injected into the body can be very toxic to the nervous system. Symptoms commonly include salivation, irregular heartbeat, and prolonged, painful erections (priapism) in men. These species are actually investigated by scientists as potential source of cure for erectile disfunction in humans.

4) Australian funnel web spider

Are australian funnel web spiders poisonous

These are another species of spiders that are feared in the southern and eastern part of Australia for their venomous bite. Their bites usually have the same side effects as that of a black widow spider.

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Cite this Article (APA Format)

Bunu. M. (2020, May 14). Venomous Spiders: Are spiders venomous?. Retrieved from

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