The terms "cellar spider" and "daddy long legs" are often used interchangeably, leading to considerable confusion. However, these names actually refer to two distinct arachnid groups, each with unique characteristics. Understanding their differences is key to appreciating the fascinating world of these often-misunderstood creatures.
What is a Cellar Spider?
Cellar spiders, scientifically known as Pholcidae, are small, fragile spiders often found in dark, damp places like cellars, basements, and sheds—hence their common name. They are easily recognizable by their long, thin legs and their characteristically shaky, erratic movements. Their bodies are typically small and light-colored, often a grayish-brown or tan.
Cellar Spider Characteristics:
- Webs: Cellar spiders create irregular, three-dimensional webs that are often messy and sticky. These webs are not used for trapping prey as much as for detecting vibrations, alerting the spider to nearby insects.
- Hunting Style: They are ambush predators, waiting patiently in their webs for unsuspecting prey to stumble in.
- Venom: While cellar spiders possess venom, it's considered harmless to humans. Their fangs are too small to effectively penetrate human skin.
- Appearance: Distinctive long, thin legs that are disproportionately long compared to their body size.
What are Daddy Long Legs?
The term "daddy long legs" can refer to two entirely different creatures, causing much of the confusion:
- Harvestmen (Opiliones): These are arachnids, but they are not spiders. They lack the characteristic two body segments (cephalothorax and abdomen) that define spiders. Instead, their bodies are fused into a single oval shape. They also lack venom glands and spinnerets (organs that produce silk).
- Cellar Spiders (Pholcidae): As discussed above, these are true spiders, often mistakenly called daddy long legs.
This ambiguity is a major source of misinformation. When people say "daddy long legs," they're often referring to the harvestmen.
Harvestmen (Daddy Long Legs) Characteristics:
- Legs: Their most notable feature is their extremely long, thin legs, often significantly longer than their body.
- Body: A single, fused body segment, unlike the two-segmented bodies of spiders.
- Defense: They lack venom, relying instead on defensive chemicals or simply dropping a leg to escape predators. The lost leg will continue to twitch, distracting the predator.
- Diet: They are primarily scavengers, feeding on decaying organic matter.
Are Daddy Long Legs (Harvestmen) Poisonous?
No. Harvestmen (the arachnids often called "daddy long legs") are not poisonous or venomous. They lack venom glands entirely. This is a persistent myth, despite having no scientific basis.
Are Cellar Spiders Dangerous?
Cellar spiders possess venom, but it is considered harmless to humans. Their fangs are too small and weak to penetrate human skin, even if they tried.
What's the Difference Between Cellar Spiders and Harvestmen?
The key differences lie in their anatomy and biology:
| Feature | Cellar Spider (Pholcidae) | Harvestman (Opiliones) |
|---|---|---|
| Body Segments | Two (cephalothorax & abdomen) | One (fused body) |
| Venom | Present, but harmless to humans | Absent |
| Silk Production | Yes | No |
| Diet | Predatory | Scavenger |
Conclusion
While both cellar spiders and the arachnids commonly called "daddy long legs" (harvestmen) are often found in similar habitats, they are very different creatures. Understanding these differences clarifies the confusion surrounding these fascinating arachnids and dispels common myths. Remember, the term "daddy long legs" is ambiguous and often leads to misunderstandings. It's always more precise to use their scientific names (Pholcidae for cellar spiders and Opiliones for harvestmen) to avoid any ambiguity.
