Spider Identification: Easy Shortcuts

As pest managers we regularly get asked to identify spiders. For some spiders, and people, this is an easy task but for many this is a challenge. Formal spider identification typically requires some sort of magnification and a very good understanding of spider anatomy. With so many spider species, you would think this is a task best suited for a professional arachnologist, however, there are a few short cuts or ‘dead giveaways’ to at least help identify the spider at a family level.

As pest managers we regularly get asked to identify spiders. For some spiders, and people, this is an easy task but for many this is a challenge. Formal spider identification typically requires some sort of magnification and a very good understanding of spider anatomy. With so many spider species, you would think this is a task best suited for a professional arachnologist, however, there are a few short cuts or ‘dead giveaways’ to at least help identify the spider at a family level.

One of the biggest mistakes most non-spider people make is underestimate the number of different spider species. There are currently 3300 described species of spiders in Australia with estimates of there being up to potentially 10,000 different species. To put that into perspective, there are currently 165 described members of the wolf spider family Lycosidae with estimates of there being potentially 1000 different species. So, in other words, there are close to 1000 different species of wolf spiders alone.

The average person assumes the identity of the spider is one that they are familiar with, disregarding all the other potential matches. For this reason, it is considered satisfactory to identify spiders at a family level only. For example: Araneidae (orb weavers), Deinopidae (net-casting spiders), Salticidae (jumping spiders), Pisauridae (fishing spiders), Sparassidae (huntsman spiders), Hexathelidae (funnel-web spiders), and Idiopidae (spiny trapdoor spiders) just to name a few.

Some easily seen features will help you identify spiders to at least a family level:

Eyes

This is by far one of the most useful features to help identify spiders, as most spider families have a unique eye arrangement. The general public might struggle to tell the difference between a wolf spider and a huntsman, but the prominent, large eyes on a wolf spider are a dead giveaway.

 

Eye arrangement of a wolf spider
Eye arrangement of a wolf spider (note the large eyes)

Spinnerets

These are the two finger-like attachments at the rear of the spider, used to produce silk. The spinnerets on some spiders are quite distinctive and can be used to differentiate spider families. The spinnerets on funnel-web and curtain-web spiders are significantly longer than that of trapdoor and mouse spiders. The spinnerets of two-tailed spiders are extremely obvious, separating them from other similar-looking species such as huntsman and fishing spiders.

 

Legs

All spiders have eight legs, however leg shape and length can be a handy diagnostic feature, such as the long spines on a lynx spider or the presence of claw tufts on brush-footed trapdoor spiders. The front legs of a huntsman are typically longer and bend laterally rather than upwards when compared to wolf spiders.

 

Two-tailed spider
The unmistakably long spinnerets of a two-tailed spider

Abdomen

This is the ‘bum’ part. Many spiders have uniquely shaped abdomens. The cigar-shaped abdomen of the white-tailed spiders quite familiar to us, but the bizarrely shaped abdomen of the lesser known whip spider or scorpion-tailed spider is unmistakable.

 

Cephalothorax

This is the head or main body part of the spider. The cephalothorax isn’t quite as variable as most other spider body parts but subtle features can be quite useful. The glossy look and lack of hairs on the cephalothorax of the funnel-web spider and the raised arch of the mouse spider can be used to distinguish from other mygalomorph spiders.

 

Chelicerae

These are the fangs of the spider. Many spiders have evolved uniquely shaped chelicerae. Both the ant-mimicking spiders and long-jawed spiders have bizarre-looking chelicerae.

 

Markings

The most obvious example is the hourglass shape on the ventral side of the redback’s abdomen, but there are many other obvious ones that most people are not aware of. The union jack symbol on the cephalothorax of members of the wolf spider genus Tasmanicosa and the coat of arms symbol on the ventral side of the badge huntsmans are really cool quirks of nature. Less subtle markings can also assist with identification; the black house spider, jungle huntsman and swift spider all have distinguishing markings.

As well as the morphological features of a spider, there are many behavioural features that can be confidently used to identify spiders. The list is endless, but the way a spider hunts its prey, sits when resting, constructs its web or burrow, constructs its egg sac or simply moves can potentially be unique amongst spiders and effectively be used to identify a spider – sometimes even without sighting the spider itself.

This is only a small selection of examples used with the limited amount of space I have here, but as you can see it can be a far sight easier to look for a few unique features rather than using a taxonomic key or memorising every key feature of every spider species.

By no means am I suggesting you learn each spider family’s distinguishing features. Simply familiarise yourself with the many different family groups and learn to visually recognise distinguishing features rather than simply looking at a spider and seeing it as simply a critter with eight legs. This is definitely an acquired skill but one we can all constantly build on, so we can be the skilled professionals that we are considered to be.

Back to pest control spiders and more information on types of spiders.

Jay Turner, Laguna Pest Control, Pest Manager of the year 2017

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