[![arachnids_signature.png](https://images.ecency.com/DQmTNZNgS8dAqqonwpFcrzYYUcxzZXS3DQah61burjLWYhS/arachnids_signature.png)](https://ecency.com/created/hive-100750)![arachnids_banner.png](https://images.ecency.com/DQmSYhrch2cW1NuxqZYL68feNDoY2MwQVTnZ8RxsqheVFAF/arachnids_banner.png) Hello, again! First, I want to give a huge thanks to everyone who upvoted and shared the [introduction post](https://ecency.com/hive-100750/@hive-100750/introductions-and-spoods)! I truly, deeply appreciate the support in spreading awareness not only of the [Arachnids community](https://ecency.com/created/hive-100750) but also of the arachnids themselves. It warms my heart to see more arachnid posts on HIVE lately! The first step in spreading knowledge of arachnids is by breaking down what seems to be intimidating or scary. The best way to combat fear is through information, and that's what this account and community is about. Let's set the stage: You see a creepy-crawly with 8 legs and the brain's first instinct is "spider". But how sure are you that it's a spider you're seeing? That's what we're going to break down in this post. What is that arachnid you see, and how can you tell? ![arachnids_divider.png](https://images.ecency.com/DQmVVBKf9YRVSEEnBJysFc7wxmcxzJYBKzZigush5wFN6rZ/arachnids_divider.png) ## TAXON Before we get into it, a quick basic introduction into taxonomy is needed. Arachnida is the "**class**" of animal in the "tree of life", under the "**Phylum**" called Arthropoda (which means joint-legged), and that phylum is under the "**Kingdom**" of Animalia (animals). The arachnid class is then divided into "**Orders**", as I quickly showed in the [introduction post](https://ecency.com/hive-100750/@hive-100750/introductions-and-spoods).

_{An excellent graphic for taxonomy, freely available from Wikimedia Commons along with a version without text for you to fill in yourself and use.}

In each Order, you have "**families**" which are similar types of that animal, for instance all crab spiders belong to the family Thomisidae. Inside the family are "**genera**" ("**genus**" is the singular form of that word) which divide the animals to their closely related types, for instance all widow spiders belong to the genus Latrodectus. Each genus contains the "**species**" that belong together. Species is not a grouping like genus or family, but is the exact animal's name. For instance, the brown widow spider found all around the world is called Latrodectus geometricus. When referring to the scientific name of an arachnid species, the genus is always added. The brown widow spider is not just "geometricus" but is always "Latrodectus geometricus" (or L. geometricus for short). This basic classification is what you'll find across all arachnid Orders. Some Orders may have additional classifications within them, as will some families. But for now, we'll focus on the basic classification system of "Order-Family-Genus-Species". In example, the brown widow spider's taxon is: - Order: Araneae - Family: Theridiidae - Genus and species: Latrodectus geometricus. As is often the case, when we aren't certain about what species an arachnid is, we can list it by its Order, family, or genus name and add "sp." instead of the species name. Most of the time, identifying an arachnid to species is near impossible without stereo microscopes and knowing what to look for in the arachnid's anatomy. So listing only the Order, family, or genus is perfectly fine and common practice. Let's say we find a black widow spider but we're not sure what species of black widow it is but we know she's in the genus Latrodectus. We'll list her as Latrodectus sp. and that lets others know it's a widow specifically, and not a different spider or arachnid. ![arachnids_divider.png](https://images.ecency.com/DQmVVBKf9YRVSEEnBJysFc7wxmcxzJYBKzZigush5wFN6rZ/arachnids_divider.png) ## ORDERS We briefly skimmed over the arachnid Orders in the introduction post, now let's go deeper. Knowing how to identify each Order will go a long way in learning how to identify the family, genus, or species of an arachnid. Firstly, what do all arachnids have in common? They all have: - 8 legs as adults, - **chelicerae** (jaw-like mouth parts), - 2 body parts called **tagmata**: the **cephalothorax** (the front part where the eyes and mouth are) and the **abdomen** (the back part, usually the largest part), - and they all have **pedipalps** (special leg-like appendages that are used for various things like sensing, mating, and defence). --- #### 1. ARANEAE (SPIDERS)

_{Graphic made by @anikekirsten for personal use only. For a more detailed spider anatomy image, click here .}

We'll start with spiders, because they're more commonly known and mostly confused with other arachnids. Spiders have fangs, which can't easily be seen in small spiders. Another iconic feature of spiders are the **spinnerets**, an organ near or at the base tip of the abdomen that produces and excretes silk, which spiders use for building webs and egg sacs or for throwing or spitting at prey. The pedipalps of spiders look like their legs, and can sometimes be long enough to look like extra legs. In summary, to identify if an arachnid is a spider you need to see: - 2 fangs (if the spider is large enough) - 2 leg-like pedipalps - spinnerets (or at least silk / webbing if the spider is small). **Araneae** currently has 131 families, and you can explore the families in the [World Spider Catalog](https://wsc.nmbe.ch/families). --- #### 2. SCORPIONES (SCORPIONS)

_{Graphic made by @anikekirsten for personal use only. For a more detailed scorpion anatomy image, click here .}

Next up, let's take a look at what defines a scorpion. This Order is perhaps the easiest to identify because the physical characteristics are very easy to see, even in small scorpions. Unlike spiders, scorpions have a tail. Seeing the division between the cephalothorax and abdomen is not so easy and can look like it's one long body. Scorpions also have 2 pincers (the claw-like limbs in the front), which are attached to their pedipalps. These features, together with the tail, are iconic in scorpions, but the tail is the most iconic: at the end of the tail is the stinger that produces and releases venom. In summary, a scorpion is identifiable by having: - 2 pincers in the front of its body - a tail that ends with a stinger. **Scorpiones** currently has 13 families, and you can explore the families in the [The Scorpion Files](https://www.ntnu.no/ub/scorpion-files/intro.php). --- #### 3. OPILIONES (HARVESTMEN)

_{Graphic made by @anikekirsten for personal use only. For a more detailed harvestman anatomy image, click here .}

Next up are the harvestmen. These arachnids are very often confused for spiders. And it's easy to see why. They look very much the same. But there is an easy way to tell them apart. Harvestmen, also called Daddy-Long-Legs, also have 2 tagmata but their body is shaped in such a way that it looks fused together. Harvestmen are also iconic because of their "curly" long legs, though some species have short legs. Another interesting fact about harvestmen is that not all of them have 8 legs! Some only get 8 legs when they become adults. They also have no venom glands and they don't produce any silk. In summary, you can tell it's a harvestman by seeing: - what looks like a one-part body - 2 short leg-like pedipalps - no webbing. **Opiliones** currently has 68 families in 5 suborders, and you can explore them in the [World Catalogue of Opiliones](https://wcolite.com/). --- #### 4. SOLIFUGAE (CAMEL SPIDERS)

_{Graphic made by @anikekirsten for personal use only. For a more detailed solifuge anatomy image, click here .}

Unlike what the name "camel spider" suggests, solifuges are not spiders. Nor are they scorpions. They're very often confused for spiders and scorpions due to them looking a lot like them. But there are differences that are easy to tell them apart by. The main difference is that solifuges have very large chelicerae. Solifuges have no silk glands or venom glands. They also have no pincers or a tail. The shape of the cephalothorax makes it look like solifuges have a "neck" and "head". The pedipalps of solifuges are often so long that it looks like they have 10 legs instead of 8. To sum it up, you can spot a solifuge by seeing: - 2 long pedipalps that look like extra legs - large chelicerae - no web - no tail. **Solifugae** currently has 12 families and you can explore them in the Western Australian Museum's [Solifuges of the World catalogue](https://museum.wa.gov.au/catalogues-beta/family-browser/solifugae). --- #### 5. PSEUDOSCORPIONES (FALSE SCORPIONS)

_{Graphic made by @anikekirsten for personal use only. For a more detailed pseudoscorpion anatomy image, click here .}

Pseudoscorpions are also known as fake/false scorpions or book scorpions. And they really do look like scorpions! The main difference is that false scorpions are tiny and they don't have a tail. Their body and pincers on their pedipalps look almost exactly like a scorpion. They also, unlike scorpions, can make silk and their venom is in their pincers. These arachnids are easy to identify, though they are difficult to see because of how small they are. To identify a book scorpion, you need to see: - a tiny body - pincers on the pedipalps - possibly some webbing - no tail. **Pseudoscorpiones** currently has 26 families and you can explore them in the [World Pseudoscorpiones Catalogue](https://wac.nmbe.ch/order/pseudoscorpiones/families/3). --- #### 6. AMBLYPYGI (WHIP-SPIDERS)