Harvestmen

Pronunciation

How to pronounce Opiliones: /ˌoʊpɪliˈoʊniːz/

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Images

Summary

Opiliones, or harvestmen, are an ancient order of arachnids characterized by their unique body structure and exceptionally long legs. They occupy diverse habitats and display a wide range of feeding behaviors, although they pose no threat to humans and are often misidentified as spiders. Their evolutionary history dates back hundreds of millions of years, showcasing their long-standing success as terrestrial arachnids.

Physical Characteristics

Body structure appears as a single segment due to the broad fusion of cephalothorax and abdomen; exceptionally long legs relative to body size, but some species are short-legged; lack of venom glands and silk glands; dimensions from millimeters to centimeters, typically does not exceed 7 mm body length; the largest known species can reach 22 mm; leg span can exceed 160 mm.

Identification Tips

Easily distinguishable from spiders by the fused body regions and a single pair of central eyes on the cephalothorax; typically have one pair of camera-type eyes oriented sideways.

Habitat

Found in forests, grasslands, wetlands, mountains, caves, chaparral, and areas altered by human activity; common under trees during the harvest season; can be found in both temperate and tropical environments.

Distribution

Global distribution except Antarctica; found on all continents with well-preserved fossils indicating their ancient presence.

Diet

Carnivorous, feeding on small arthropods, plant material, fungi, and detritus; some are omnivorous.

Life Cycle

Undergo egg, juvenile, and adult stages; pass through four to eight nymphal instars to reach maturity with most known species having six instars.

Reproduction

Most species reproduce sexually through direct fertilization; a few species can reproduce parthenogenetically; females can store sperm after mating.

Predators

Predators include mammals, amphibians, and other arachnids such as spiders and scorpions.

Conservation Status

Certain cave-dwelling species in Brazil and the United States are listed as endangered or vulnerable, depending on local regulations and human impact; no comprehensive red list for harvestmen exists in all regions of their distribution.

Ecosystem Role

Play a role in controlling populations of small arthropods and contributing to nutrient cycling in their habitats.

Cultural Significance

Commonly known as 'Daddy-long-legs'; the name has also been mistakenly applied to other unrelated groups. Their presence often associated with cultural superstitions regarding harvests.

Health Concerns

Do not pose any danger to humans; misunderstandings exist that they are highly venomous, which is untrue.

Collecting Methods

• Light trapping
• Hand collection
• Pitfall traps

Preservation Methods

• Ethanol preservation
• Drying
• Card mounting

Evolution

Fossil record indicates that Opiliones have changed little over 400 million years, highlighting their ancient lineage; some studies suggest their origin may trace back to around 473 million years ago during the Ordovician.

Similar Taxa

• Spiders (Araneae)
• Scorpions (Scorpiones)
• Pseudoscorpions (Pseudoscorpiones)
• Camel spiders (Solifugae)

Misconceptions

Commonly mistaken for highly venomous creatures; urban legend claims them to be the most venomous animal in the world, but they lack venom glands and cannot bite humans.

Tags

• Opiliones
• Harvestmen
• Daddy-long-legs
• Arachnids
• Ecosystem importance