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Why Are Spiders In Australia So Big?

Why Are Spiders In Australia So Big?

If you have ever been to Australia and happened to see a spider you may have been surprised by their impressive difference in size from you are used to seeing. This is especially true for many first time travelers from the United States, Canada and the United Kingdom. But what makes spiders in Australia so big?

It’s because Australia’s climate is warm and insects, including spiders, tend to grow bigger in warmer places and nearer to the equator. In addition, the Australian bushlands provide a steady source of food supply that aid in their growth as well. 

Why Is Australia Home to Big Spiders?

Scientists reveal that cold-blooded animals, including insects and crabs, tend to grow bigger in warm places. Anthropods are said to be sensitive to temperature. However, the reverse applies to species found in water. It is said that the lower level of oxygen in water causes animals to reduce their body size compared to those on land. 

Given that Australia generally has an arid climate and is classified as desert or semi-desert, it makes sense why spiders here grow very big. Australia’s northern section is hot and humid in the summer and warm and dry in the winter. The southern areas, meanwhile, tend to be more temperate to warm. The daytime temperatures in the summer are usually between 25 and 30°C. The conditions in the desert in central Australia are more extreme with temperatures sometimes reaching 50°C and no possible rainfall for years.

Aside from the spider body’s sensitivity to temperature, the duration of warm periods also affects how spiders and other insects grow. Shorter warm periods means insects only have little time to reach maturation and grow. This is because most insects can’t survive the cold. However, in places where warm periods are longer, these insects are allowed to grow larger before being able to reproduce.

Warmer Climate Means More Food and Shelter

For insects, including spiders, a warmer climate means more food and better shelter. The warm climate generally offers a favorable combination of higher precipitation and more sunlight, thus making the soil richer in nutrients. This means spiders in Australia enjoy an abundance of nutritional content in soils plus the energy to grow bigger. 

Aside from that, the warm temperature creates denser and larger foliage where spiders can hide in. This gives them more protection from predators, thus increasing their growth and survival rates. 

Large Swathes of Bushland Are Home to More Insects 

Australia is home to swathes of bushland. This is another contributing factor to why spiders here grow big. Spiders enjoy an abundance of smaller insects to prey on because Australia is home to plenty of small fragments of bushland. This means spiders get to feast on insects, even in the urban setting. Adding to this is the warm climate that gives spiders more energy, thus making them more active to hunt for food and grow bigger.

What Are The Biggest Spiders In Australia?

From 25 mm to 180 mm in length, here are some of the biggest spiders in Australia:

 Crab Spider: These spiders are also known as flower spiders. They hunt for prey during the day and are common throughout Australia, but they’re mostly found in tropical and subtropical areas. Crab spiders are called as such because they have laterigrade legs, which allow them to walk sideways as crabs do. Males are smaller with 6 mm in length, while the female crab spiders can reach a length of 10 mm.

Large Crab Spider From Australia

Wolf Spider: Wolf spiders grow to about 25 mm in length, which is about an inch. In Australia, there are about 400 species of this kind of spider. Known for their agile movements and relatively large size, wolf spiders can be a very scary creature to stumble upon.

Scary Looking Wolf Spider From Australia

Australian Bird-Eating Spider: This spider is among the large and aggressive types found in the more arid regions in Australia. The largest bird-eating spider may have a body length of 60 mm, leg length of 160 mm, and fangs that are 10 mm long. Some species of the Australian bird-eating spider are known as whistling or barking spiders because they produce sounds when they rub their palps. The color of this kind of spider varies from reddish to grey-brown.

Australian Bird Eating Spider

The Australian bird-eating spider is not just intimidating and scary due to its size and appearance, but it’s also equally tough as a predator. It can kill a dog or a cat and often go after frogs, rodents, aside from the insects found in the warmer parts of the region.

Huntsman Spider: When it comes to size and massiveness, the huntsman spider sure knows how to impress. The giant of this species boasts 180 mm in length, 30 cm of leg span, which makes it the largest spider by diameter. The size is about that of a dinner plate.

Large Huntsman Spider From Australia

Coming from the Sparassidae family, huntsman spiders are known for their speed and mode of hunting, thus their name. Sometimes, the larger species are called wood spiders because they prefer woody places, such as woodpiles, wooden stacks, forests, and mine shafts. The average-sized huntsman spider may have 1.8 cm length and a leg span of 15 cm. 

Are These Big Spiders Dangerous?

Even though Australia is home to many spiders — with an estimated 10,000 species found in various ecosystems  — most of them are not considered dangerous. In fact, it is said that bees typically pose more threat than these eight-legged creatures. There have been more deaths recorded due to allergic reactions to bees.

Spiders have an excellent reputation of inciting fear, but they don’t attack unless they’re threatened or harmed. Aside from that, only a few of the large species have fangs to bite and puncture the human skin. 

Most Dangerous and Venomous Spiders in Australia

Out of the many kinds of spiders found all over Australia, there are only two you should stay away from — the red-back spiders and the Sydney funnel-web spiders.

Red-Back Spider: This spider is believed to have originated in the South Australian deserts. However, today, they’re all over Australia. The red-back spider is highly venomous but is only life-threatening to a child. Also, since the introduction of its anti-venom in the 1950s, there have been no deaths recorded so far.

venemous redback spider from australia

Redback spiders prefer to live in hot regions. They can survive in very harsh conditions as long as there is plenty of food and enough shelter. These spiders are also said to inhabit close to where humans live. Watch out for them in sheds, outdoor piles, or stack of woods. 
Sydney Funnel-Web Spider: Sydney funnel-web spiders are found in Australia’s moist forest regions, mainly in the east coast and highlands from Tasmania to Northern Queensland. Outside their natural habitat, Sydney funnel-web spiders prefer to live in shady and sheltered spots that are always cool and humid.

Redback spiders prefer to live in hot regions. They can survive in very harsh conditions as long as there is plenty of food and enough shelter. These spiders are also said to inhabit close to where humans live. Watch out for them in sheds, outdoor piles, or stack of woods.

Sydney Funnel-Web Spider: Sydney funnel-web spiders are found in Australia’s moist forest regions, mainly in the east coast and highlands from Tasmania to Northern Queensland. Outside their natural habitat, Sydney funnel-web spiders prefer to live in shady and sheltered spots that are always cool and humid.

dangerous sydney funnel web spider from australia

With its fangs larger than that of a brown snake, this spider is nothing short of powerful.  Its bite can pierce through nails and toenails. Aside from its powerful bite, its venom can attack the nervous system, which can greatly damage the internal organs. It’s also important to note that if the bite comes from a male, it can be lethal. Having said this, the Sydney funnel-web is considered the deadliest spider in Australia. 

What to Do When You Encounter Big Spiders

Australia may have a reputation for being home to some of the most dangerous spiders in the world. But contrary to popular belief, you don’t stare death in the face every single time you see a big spider.

However, if you encounter a big spider, here’s what you can do:  

  • Don’t panic. It may seem hard to suppress a panic attack, especially when faced with a big spider, but keep in mind that most of Australia’s spider species aren’t venomous. In fact, they are even beneficial to your home as spiders keep your house clean of other insects. Also, the Sydney funnel-web and red-back spiders are the only ones that may pose a danger to you.
  • Try to remove the spider. Do this only if you can. Use anything that can push the spider out of your way and out of the house. 

How to Get Rid of a Big Spider at Home:

  • First of all, if you’re sure — or almost confident — that the spider is dangerous, call the nearest pest control center in your area. Never touch a spider or remove it on your own unless you’re sure it’s not the dangerous kind. Utilize our exterminator search tool to help find a qualified professional.
  • If you’re confident that the big spider isn’t dangerous, you can catch it using a container. Seal it and put breathing holes. You can either release it later somewhere far from your place or bring it to an insect or animal center.
  • While it’s not advised to kill a spider, however, if you believe it’s the only way to get out of possible danger, just make sure to hit it or kill it with a bug spray accurately.

How Do Australians Handle Big Spiders? 

Some may find it hard to believe that for a country home to about 10,000 species of spiders, Australians treat spiders with respect. This is true despite the continuously reported cases of spider bites all over the region. 

This can be explained by how Australians view living creatures, including the insects. They believe that every living thing should be allowed to live and that each one has a specific role in this world. Spiders aren’t here to simply scare people; they’re also an essential part of the ecosystem. 

So when Australians encounter big spiders in their homes, don’t expect them to kill it right away. If there’s no one in the house who can confidently capture the spider and relocate it outside where it belongs, they call the experts who can do a better job. 

It’s interesting to learn why Australia is home to big spiders, but what’s even more interesting is how Australians treat them with respect no matter how scary or dangerous they may appear.

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