Changing Planet

Giant “Daddy Longlegs” Discovered in Laos

This harvestman has especially long legs – a span measuring more than one foot (appx. 33 cm) (Image: © Senckenberg)

The sight of a daddy longlegs scurrying across your backyard can be unnerving—typically the spindly legs of these creatures, also called harvestmen, are an inch or two long. But how would you feel about finding a giant one in a dark cave?

If you’re an arachnologist, like Dr. Peter Jäger of the Senckenberg Research Institute in Frankfurt, Germany, you’d be thrilled–especially if you found one of the world’s largest daddy longlegs.

On a recent trip to Laos, Dr. Jäger discovered a very leggy harvestman whose leg span is more than one-foot wide (about 33-plus cm). Experts are still working to properly identify it on a species level.

Often misidentified as spiders, harvestmen belong to their own, separate order—the Opiliones. They are arachnids but are distant “cousins” to true spiders. They both have eight legs, but very different bodies. Harvestmen’s bodies usually look like one big round or oval segment, while spiders’ bodies have two very distinct sections. Another difference: Harvestmen do not spin webs (they can’t produce silk).

The Huge Harvestman

Dr. Jäger was in Laos in April to film a major TV production. “In between takes I collected spiders from the caves in the southern province of Khammouan. In one of the caves I discovered a harvestman that was absolutely huge.”

No name yet – the harvestman is only one of many huge arthropods in Laos. (Image: © Senckenberg)

The leg span of the gigantic male harvestman was more than one foot (slightly more than 33 cm) putting it in close contention for the world’s largest. The current record-holder is a South American harvestman with one-foot-one-inch leg span (just over 34 centimeters).

The giant huntsman is not the first giant “creepy crawly” to be found in Laotian caves. Other arthropods with supersized dimensions have been found in the same region – the Laotian huntsman spider Heteropoda maxima with a leg span of up to 11 inches (30 cm), the whip scorpion Typopeltis magnificus with a span of 10 inches (26 cm) and the predatory centipede Thereuopoda longicornis with a total span of almost one foot, three inches (about 40 cm).

“What mechanisms or factors are responsible for this frequency of gigantism is still unclear,” says Jäger. The only thing that seems certain is that there is a limit to growth—either due to the lack of oxygen supply to the long appendages or because when speed becomes reduced when legs grow too long to flee or catch prey effectively.

The Arachnid With No Name

Dr. Jager’s find was one of many specimens collected in the cave, and the giant harvestman remained hidden among the other organisms. Only one the findings were sorted and labeled did he realize he had a giant discovery on his hands. But efforts to positively identify the species have been inconclusive so far.

Jäger’s speciality is not harvestmen, but huntsman spiders. “In attempting to categorize the harvestman properly, however, and give it a scientific name, I soon reached my limits,” says Jäger. He consulted specialist Ana Lucia Tourinho from the National Institute for Research of the Amazon (INPA) in Manaus, Brazil, who is currently a visiting academic at the Senckenberg Arachnology lab. Together, they could only conclude that it is probably the genus Gagrella in the Sclerosomatidae family.

“It’s a shame we can’t identify such an exceptional discovery correctly, i.e. its species,” says Jäger. “We haven’t dealt with these and related genera from China and neighboring South East Asia before. Specialists are also unavailable due to the fact that descriptive taxonomy is no longer the main focus of research funding.”

Jäger and his team feel that the harvestmen of the Sclerosomatidae family have invaluable research potential because specimens can be found in virtually every habitat and constitute an ecologically important predator group in the natural food chain. Hunstmen could serve as an indicator of the ecological state of the natural and cultural scenery.

Dr. Jäger would now like to continue to investigate the Sclerosomatidae family along with his Brazilian colleague and in collaboration with other scientists in Germany, China and Japan. The findings should then be applicable to other groups and regions. “We want to avoid a situation in future where we again lack the experts to classify such unique creatures,” says Jäger.

Focusing on content that entertains, astounds, and informs, Amy Briggs is freelance writer and former senior editor with National Geographic Books . The author of National Geographic Angry Birds Space, Briggs worked closely with National Geographic NewsWatch's David Braun on National Geographic Tales of the Weird. Excited by all things trivial, odd, and just unusual, she lives in Virginia with her family.
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  • Mary Fowler

    I have seen a nest of daddy long legs under a bridge behind my house. There were about 200 of them nestled together.

  • For the Non-Metric

    33cm is approximately 13 inches (33cm = 12,9921 inches), just in case others were wondering. Cheers!

  • Tracy F

    If Daddy Long Legs do not produce a web, why do I see them in a spider web?

  • Neo

    Interesting discovery but why do I see them on webs if they don’t produce webs. Or are they stealing homes for other spiders.



  • Amadea K N

    Hey that so cool and unique.. but a little creepy..

  • GNF

    No one will believe it anyway, but here goes: I once saw a huge daddy long legs OR harvestman spider. I think it was a harvestman because it had one body segment and its body was dark orange in color and only slightly smaller than an average chicken egg. It’s legs were about 2.5 feet long. It came walking up onto the patio out of a heavily wooded area and I heard it walking. That’s how big it was. When it saw me it stopped and I just looked at it. I thought it was a joke, like I was on a hidden camera show or something. After standing there for about 10 seconds, it turned around and walked right back where it came from into the woods, climbing over leaves and logs. I didn’t have a camera on me, but I have never forgot it. I started to think it got affected by some kind of radiation or something because it was so hard to believe how it got so big.

  • Justin

    I have been in a cave walked back 20 feet and something fell on me I shined my light on the walls and there was tens of thousands of daddy long legs on the walls I booked it out so fast..some of them I’d say we’re easily 25cm long

  • Richard

    I think I remember seeing a giant daddy long legs in a house I lived in as a kid. It was standing on the wall hear the laundry and toilet area. From memory I think it was probably at least a foot long. I have never seen anything like it since. I can’t be sure but it was certainly impressively big.

  • Adam

    I’ve seen bigger in Texas. Around 3ft. Round body the size of a walnut. Didn’t have cellphones back then though.

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