The term “grand daddy long legs” often causes confusion, referring to several distinct creatures with long, slender limbs. This common name can lead to misunderstandings about their biology and behavior. This article will clarify which animals are typically associated with this moniker and delve into their unique characteristics. Understanding these differences helps to appreciate the diverse world of arthropods.
The Name’s Many Meanings
The familiar phrase “grand daddy long legs” is broadly applied to three different types of arthropods, each belonging to a separate biological group. First are harvestmen, which are arachnids in the order Opiliones, distinct from true spiders. They are recognized by their fused, oval-shaped bodies and typically long legs. Second are cellar spiders, members of the spider family Pholcidae, which are true spiders known for their delicate appearance and the messy webs they construct. Lastly, crane flies (Tipulidae) are insects, often mistaken for large mosquitoes, characterized by their long legs and winged bodies.
Unpacking the Harvestman
Harvestmen, classified under the order Opiliones, are arachnids but are not spiders, despite their similar appearance. Their body structure is a key differentiator, as their cephalothorax and abdomen are broadly joined, giving them a single, oval-shaped body, unlike the distinct two segments of spiders. They possess only two eyes, positioned on a raised turret-like structure called an ocularium, which can only sense light and dark rather than forming images. Their second pair of legs is the longest and functions as sensory organs, helping them navigate their environment.
Harvestmen thrive in various terrestrial environments, including forests, grasslands, and even human dwellings, often seeking shelter in moist, dark places during the day. Most species are nocturnal, becoming active at night to forage. Their diet is varied; they are omnivores, consuming small insects, mites, plant material, fungi, and decaying organic matter, including dead organisms and bird droppings. Unlike spiders, harvestmen ingest solid food, tearing it apart with their chelicerae, rather than liquefying it externally. Some species exhibit gregarious behavior, forming large aggregations in protected areas, which may offer protection from predators and environmental extremes.
Dispelling the Myths
A persistent misconception suggests that “grand daddy long legs” possess highly potent venom but are incapable of biting humans due to short fangs. This claim is inaccurate for both harvestmen and cellar spiders. Harvestmen do not have venom glands or fangs, meaning they are incapable of producing or injecting venom. Their mouthparts are small pincers, used for grasping and tearing food, and are too delicate to break human skin.
Cellar spiders, while true spiders, also do not pose a threat to humans. They possess venom glands and fangs, but their venom is mild and has negligible effects on mammals. While their fangs are capable of piercing human skin, bites are uncommon and result in only a mild, temporary stinging sensation. No scientific evidence supports the claim of highly toxic venom or that their fangs are too short to bite.
Ecological Contributions
Harvestmen and cellar spiders both play roles within their ecosystems, contributing to natural processes and population control. Harvestmen are generalist feeders, acting as both scavengers and predators. They consume decaying plant and animal matter, including bird droppings, and prey on small soft-bodied insects such as aphids and mites. Their feeding habits assist in nutrient cycling by breaking down organic material.
Cellar spiders are opportunistic predators, effectively controlling populations of various small arthropods. They are known to capture and consume mosquitoes, gnats, flies, and even other spiders. Their presence in homes and gardens can help manage common household pests.