Spiders with Seven Legs: Unraveling the Mystery

Spiders are fascinating creatures, and you might be surprised to learn that some species even have seven legs. While most spiders have eight legs, there are cases where a spider can lose a leg in its lifetime, leaving it with only seven.

These seven-legged spiders are quite remarkable, as they can still move around efficiently and hunt for their prey. Various species can exhibit this trait, and it’s interesting to explore how these arachnids adapt to life with one less leg. So, get ready to dive into the world of spiders with seven legs and learn about their unique characteristics.

Understanding Spiders

Spiders are part of the arachnid class, a group of joint-legged invertebrates that also includes scorpions, ticks, and mites. They belong to the broader category of arthropods, which consists of insects, crustaceans, and other animals with exoskeletons. Some spiders have a unique feature: they possess seven legs instead of the usual eight.

The origin of seven-legged spiders is often due to injury or a genetic abnormality. While it may seem strange, many spider species are able to adapt and function well even with this variation in their anatomy.

These arachnids can be both beneficial and harmless to humans. For instance, they play a crucial role in controlling insect populations, as they prey on various pests. Their ability to spin silk is another remarkable feature that sets them apart from other arthropods.

Features of spiders include:

• Joint-legged invertebrates
• Part of the arachnid class
• Possess exoskeletons
• Able to produce silk

Characteristics of seven-legged spiders:

• Often due to injury or genetic abnormality
• Can function well despite leg variation
• Contributes to controlling insect populations
• Possess the same remarkable silk-spinning ability as eight-legged spiders

As you explore the fascinating world of spiders, remember that their diversity includes those with seven legs, which are just as capable and interesting as their eight-legged kin.

Anatomy of Seven-Legged Spiders

Key Body Parts

Seven-legged spiders have similar body parts to their eight-legged counterparts. They have a cephalothorax (head and thorax combined), an abdomen, and seven legs. Like other spiders, their mouthparts include chelicerae with fangs, while their head houses the eyes and mouth.

Color and Size

These spiders come in various colors and sizes, ranging from tiny to rather large. For instance, widow spiders are mostly black, while jumping spiders can be colorful and vibrant.

Unique Anatomy Features

A key difference between seven-legged spiders and common spiders is the number of legs. Seven-legged spiders possess one less pair of appendages.

Difference from Eight-Legged Spiders

• Seven-legged spiders have seven legs instead of the usual eight.
• This might be due to a developmental aberration or losing one leg in an accident.

Comparison with Other Arachnids

Seven-legged spiders are still part of the arachnid family, which includes:

• Scorpions
• Mites
• Ticks
• Harvestmen

They share similar features like having a two-part body and jointed appendages.

Types of Seven-Legged Spiders

Some examples of spiders that could be found with seven legs are:

• Wolf spiders
• Black widow
• Brown recluse
• Jumping spider

These species may have individuals that exhibit a missing leg due to various reasons.

Behavior and Survival Tactics

Seven-legged spiders still display the same behavior and survival tactics as other spiders:

• Hunting for prey
• Spinning webs using silk
• Climbing surfaces

Their one less leg doesn’t seem to impair their overall ability to survive.

Significance of Seven Legs

Although having one fewer leg might mean less maneuverability, seven-legged spiders still manage to adapt and function just like their eight-legged relatives.

Interaction with Humans

Seven-legged spiders are generally not dangerous to humans. However, some, like the black widow or brown recluse, could inflict venomous bites if threatened. Be cautious when encountering spiders in their natural habitat.

Artistic Inspiration

The uniqueness of a seven-legged spider may even inspire artists to create artistic representations or include them in stories, celebrating their adaptability and resilience.

Seven-Legged Spiders Across the Globe

These spiders can be found in various habitats, from North America to other continents. While not commonly seen, encountering one is indeed a rarity worth noting.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Hawaiian Argiope

A golden bell spider
Aloha –
Didn’t see these girls on your site, so here you go. These are not that large, yet. Can’t get a ruler near them since they’re rather shy. One has only 7 legs. Their webs don’t have the ususal white zig zag lines which perhaps indicates maturity (just guessing). Haven’t seen any males around them yet. Yes, I have an outdoor shower. Therefore they’re titled that way. Mahalo no (thanks indeed) for your excellent site.
Eliza

Hi Eliza,
A bit of research could probably lead us to a scientific name for your Hawaiian Argiope, but we are satisfied with your common name of Golden Bell Spider for now. thanks for the images to add to our ever growing archive.

Letter 2 – Whip Spider from Peru

Subject:  Strange-Looking Spider
Geographic location of the bug:  Tamshiyacu Tahuayo Regional Conservation Area, Loreto, Peru
Date: 06/15/2018
Time: 10:51 PM EDT
Your letter to the bugman:  Hello-
I was in Peru last month and found this unique-looking spider in my canoe. It is definitely a spider, as it used a silk dropline and had its body divided into two distinct parts (it only had 7 legs, but I suspect it originally had 8 and lost one). I am at an utter loss to what species it is. Would you please be able to help identify it? I apologize for the lack of a better-quality picture.
How you want your letter signed:  Captain Nemesis

Dear Captain Nemesis,
This is quite an unusual looking Spider.  It reminds us of of the Scorpion Tailed Spider from Australia, though we do not believe your individual is in the Orbweaver family.  We are posting your image while we attempt to identify your unusual Spider.  Perhaps Cesar Crash of Insetologia will recognize it.

Update:  Thanks to Karl who submitted a comment identifying this as a Whip Spider in the genus Ariamnes, and providing a link to pBase.  Arachnidos de Centroamerica also has a matching image.