This is Part 1 of a 3 part series. When you’re finished with this article, check out Part 2: Opiliones - Harvestmen... Of SOULS? and Part 3: Pholcidae - Does Death Await You In The Basement? (coming soon)
It is a commonly held belief that daddy long legs is the most venomous spider in the world, but its fangs are too small or too weak to break human skin. Is this true? Before we can tackle this question, we first need to come to a consensus: when you think of a daddy long legs, what do you imagine?
Both of the creatures pictured above are known colloquially as a daddy long legs, although I am not sure where the ambiguity comes from. My first thought was that it may have something to do with regional vernacular, but I haven’t been able to find any information on the subject. I guess it just depends on what you heard growing up. Personally, I always called the thing on the left a daddy long legs, and the thing on the right was just a spider. What I refer to as daddy long legs is actually a harvestman, and the image on the right is a cellar spider.
So, What’s The Difference?
To the casual observer, both of these specimen look like spiders. I mean, they both have eight legs, right? (Although, the harvestman was missing a leg.) In reality, these two little animals couldn’t possibly be much more different. They are both arachnids, but they are not both spiders. Most people assume that the term “arachnid” refers only to spiders, which is understandable since it is derived from the Greek word arakhne, which means spider. However, the class Arachnida also includes other 8 legged creatures like scorpions, ticks, mites, and solpugids, as well as our harvestman.
All spiders are found within the order Araneae. Key features that distinguish them from other arachnids are their general body design, fangs attached to venom glands, and spinnerets that produce silk. Harvestmen are found within the order Opiliones. Here in North America, we are only accustomed to seeing the long legged variety, but you might be surprised to learn that not all Opiliones have such disproportionate appendages. Some, especially in more tropical locations, have much shorter legs. However, since this article is about daddy long legs, we’ll leave their shorter legged cousins for another discussion.
A close side-by-side examination of a cellar spider and a harvestman reveals several key differences between the two that illustrate how they are so distantly related. Both have two body segments (cephalothorax and abdomen), but in spiders those segments are visibly separated by a thin section called a pedicel. In the harvestman, the boundary between cephalothorax and abdomen is not easily seen. Additionally, the body of the harvestman is segmented, and it has two eyes instead of the 6 or 8 found on most spiders.
So, these are the suspects. Tomorrow we will take a more in-depth look at the harvestman to find out if this odd looking creature possesses the most powerful venom in the world.