What Bug Has 10 Legs and Looks Like a Spider?
The creature you’re likely thinking of is a harvestman, also known as a daddy longlegs, which is an arachnid, but not a spider, that indeed possesses 10 visible appendages, although only 8 are legs.
Understanding Harvestmen: Beyond the “Bug” Label
Many people mistakenly refer to harvestmen as “bugs” or “spiders.” However, neither term is entirely accurate. Harvestmen belong to the order Opiliones within the class Arachnida, making them relatives of spiders, mites, scorpions, and ticks. While they share ancestry, they have evolved distinct characteristics that separate them from true spiders. The “10 legs” perception comes from the fact that they have two pedipalps, which are short appendages near the mouth that can resemble a fifth pair of legs.
Distinctive Features of Harvestmen
Harvestmen exhibit several key differences compared to spiders:
- Body Structure: Unlike spiders, which have a distinct separation between the cephalothorax (head and thorax fused) and abdomen, harvestmen have a single, oval-shaped body. This gives them a more compact, unified appearance.
- Silk Production: Spiders are renowned for their silk-spinning abilities, using silk for webs, egg sacs, and other purposes. Harvestmen, however, do not produce silk.
- Venom: True spiders typically possess venom glands and fangs for capturing and subduing prey. Harvestmen lack venom glands entirely. Their method of feeding is quite different.
- Eyes: Most spiders have multiple pairs of eyes arranged in various patterns. Harvestmen typically have only one pair of eyes, located on a raised structure on the cephalothorax.
- Leg Autonomy: Harvestmen possess a remarkable defense mechanism called autonomy. They can detach one or more of their legs when threatened. The detached leg continues to twitch, distracting predators while the harvestman escapes. This is where the common name “daddy longlegs” comes from, implying the long legs are easily lost.
Ecological Role of Harvestmen
Harvestmen are widespread and abundant in various terrestrial habitats, playing an important role in ecosystems as decomposers and predators. They are often found in:
- Forests: They are commonly found in leaf litter, under logs, and on tree trunks.
- Grasslands: Some species inhabit grasslands and meadows.
- Caves: Certain harvestmen are adapted to cave environments.
- Gardens: They can be found in gardens, where they help control populations of small insects and other invertebrates.
Harvestmen are omnivores and scavengers. Their diet consists of:
- Decomposing organic matter: They feed on decaying plant and animal material, contributing to nutrient cycling.
- Small insects: They prey on aphids, mites, and other small insects.
- Fungi: They consume fungi and other microorganisms.
Dispelling Myths about Harvestmen
There are many myths and misconceptions surrounding harvestmen, often perpetuated by their spider-like appearance. One common myth is that harvestmen are the most venomous creatures on earth, but their fangs are too short to penetrate human skin. This is entirely false; as previously stated, harvestmen have no venom glands at all.
Another misconception is that they are spiders. While related, harvestmen possess key distinguishing characteristics that separate them. Hopefully, now you know what bug has 10 legs and looks like a spider!
Are harvestmen spiders?
No, harvestmen are not spiders, although they are closely related. They belong to the order Opiliones, while spiders belong to the order Araneae. Key differences include their body structure (single oval body vs. distinct cephalothorax and abdomen in spiders), lack of silk production in harvestmen, and absence of venom glands in harvestmen.
Do harvestmen bite?
Harvestmen do not possess venom glands or fangs, so they cannot bite in the same way that spiders do. Their feeding habits are mainly focused on scavenging and consuming small invertebrates.
Are harvestmen dangerous to humans or pets?
Harvestmen are completely harmless to humans and pets. They do not bite, sting, or produce any venom. In fact, they are beneficial in gardens and ecosystems because they feed on decaying matter and control small insect populations.
What do harvestmen eat?
Harvestmen are omnivores and scavengers. Their diet includes decaying organic matter, small insects (such as aphids and mites), and fungi. They play a crucial role in nutrient cycling and decomposition.
Why do harvestmen have such long legs?
The long legs of harvestmen are thought to provide them with several advantages, including enhanced sensory perception, improved mobility, and better access to food sources. The leg autonomy defense mechanism also relies on the length of the legs.
How can I tell the difference between a harvestman and a spider?
The easiest way to distinguish between a harvestman and a spider is by observing their body structure. Harvestmen have a single, oval-shaped body, while spiders have a distinct cephalothorax and abdomen. Additionally, harvestmen lack silk-spinning abilities and venom glands, which are characteristic of spiders. Another easy way is to see if you can easily distinguish the head from the body. If not, it’s probably a harvestman.
Where do harvestmen live?
Harvestmen are found in a wide variety of terrestrial habitats around the world, including forests, grasslands, caves, and gardens. They prefer damp, shady environments with plenty of decaying organic matter.
What is the lifespan of a harvestman?
The lifespan of a harvestman varies depending on the species and environmental conditions. Some species may live for only a few months, while others can live for up to a year or more.
Do harvestmen have a brain?
Harvestmen, like other arachnids, have a centralized nervous system, but their “brain” is relatively simple compared to vertebrates. The central nervous system is concentrated in the cephalothorax (in spiders) or in the single body segment (in harvestmen).
Are “daddy longlegs” spiders or harvestmen?
The term “daddy longlegs” is commonly used to refer to both harvestmen (Opiliones) and cellar spiders (Pholcidae). However, it is more accurate to use “daddy longlegs” for harvestmen. Cellar spiders are true spiders, while harvestmen are not. Therefore, if you’re thinking of what bug has 10 legs and looks like a spider, you’re most likely thinking of a daddy longlegs harvestman.
Do harvestmen have any predators?
Harvestmen have several predators, including birds, reptiles, amphibians, spiders, and other invertebrates. Their leg autonomy defense mechanism helps them escape from predators.
Are harvestmen beneficial to humans?
Yes, harvestmen are beneficial to humans in several ways. They help control populations of small insects and other invertebrates in gardens and ecosystems. They also contribute to nutrient cycling by feeding on decaying organic matter. Ultimately, knowing what bug has 10 legs and looks like a spider, and understanding its harmless nature, allows us to appreciate their role in the environment.