Fluff ball? Clump of spiders? Viral video shows something else

A video circulating around the net shows what looks to be a scary clump of spiders, but in reality it shows a harmless cluster of opillonids, aka "daddy long legs" just trying to stay warm.

The nickname "daddy long legs" and the appearance of the creepy crawlies have contributed to the confusion.

Opillonids, according to the UC Riverside Department of Entomology, are arachnids in the order Opiliones and aren’t even spiders.

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Keep in mind that all spiders are arachnids, but not all arachnids are spiders. Opillonids, also called harvestmen, consist of one basic body segment — plus legs — while spiders have two main body parts: the cephalothorax and abdomen.

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Harvestmen are not at all poisonous to humans.

"These arachnids make their living by eating decomposing vegetative and animal matter although are opportunist predators if they can get away with it," a fact sheet released by the university shares. "They do not have venom glands, fangs or any other mechanism for chemically subduing their food. Therefore, they do not have poison and, by the powers of logic, cannot be poisonous from venom."

Paglo Barroeta posted the video online. He, or whoever shot the footage, was not in any danger when he poked the toupee-resembling clump with his finger.

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As for why opillonids (also called harvestmen) gather in such a tight mass, Brazilian arachnologist Ricardo Pinto-da-Rocha can explain.

In his book "Harvestmen: The Biology of Opiliones," he and his colleagues mention that harvestmen are sensitive to temperature changes and "are inefficient in avoiding water loss."

Harvestmen's super thin legs and bodies don't offer much protection, so these arachnids tend to clump together, particularly during the fall, to retain warmth and moisture and to guard against predation.

"Daddy long legs" is a nickname that also refers to actual spiders (Pholcidae), which you might see hanging around your home and garage. They do possess a small amount of venom for hunting their tiny prey, but are not aggressive. They are also not very social with each other, according to a University of Michigan fact sheet, and only come together to mate.

Daddy long legs spiders, also called cellar spiders, eat everything from flies to mosquitoes. Since their menu includes insect pests that can be dangerous to humans, it's best to just leave them be or gently move them outside.