Is a granddaddy long legs a spider? This common question often leads to confusion, as the creature known by this familiar name frequently appears in homes and gardens. Understanding its true identity involves distinguishing between different groups of arachnids.
Understanding the Common Name
The term “granddaddy long legs” is a common name that can be misleading because it refers to two distinct types of arachnids. One group is the Harvestmen (Order Opiliones). The other includes certain species of Cellar Spiders (Family Pholcidae). While both are arachnids, one is a true spider, and the other is not. This shared common name is the source of much popular misunderstanding.
The Spider Among Them: Cellar Spiders
Cellar Spiders (Family Pholcidae) are true spiders. These arachnids possess the defining characteristics of spiders, including a body divided into two distinct segments: a cephalothorax (fused head and chest) and a separate, often oval-shaped abdomen. Cellar spiders also have fangs (chelicerae) to inject venom into their prey. They are capable of producing silk and constructing the messy, irregular webs often seen in undisturbed areas like the corners of rooms, basements, or attics.
The Non-Spider: Harvestmen
Harvestmen (Order Opiliones) are arachnids but not true spiders. A primary distinction lies in their body structure; Harvestmen have a single, fused body segment, where the cephalothorax and abdomen appear as one continuous oval or bean-shaped unit. Unlike spiders, Harvestmen do not possess fangs; instead, they have pincer-like mouthparts (chelicerae) for grasping and chewing food. They also lack silk glands, so they cannot produce silk or spin webs.
Most Harvestmen typically have two eyes, often located on a small turret-like mound on their fused body, which differs from the multiple eyes found in most spiders. These creatures are often scavengers, feeding on decaying organic matter, small insects, or plant material, rather than actively hunting larger prey.
Addressing the Venom Myth
A persistent myth suggests that granddaddy long legs are highly venomous but cannot bite humans due to short fangs. This claim is inaccurate for both types of arachnids commonly referred to by this name. Harvestmen (Order Opiliones) do not possess venom glands at all, making them completely harmless to humans.
Cellar Spiders (Family Pholcidae), being true spiders, do produce venom. However, their venom is considered very mild and poses no medical threat to humans. While they can bite, their fangs are quite small, making it difficult for them to penetrate human skin effectively, and any bite typically results in only a mild sensation with no lasting effects.