The stone actually grew hair?! But the truth is scarier than you think...

In the autumn in Alaska's Glacier Bay Park, people discovered that stones actually grew hair.

It looks pretty dense. | atlasobscura

In Lake Chapala, Mexico, people have also found stones with long hair, and some of these stones are covered with a layer of black, furry material.

"What's so special about this? It's just a bunch of moss." I believe many people would think it was just a plant or fungus clinging to the stone, just like this tourist. However, when he sat next to this bunch of "moss", he was horrified to find that this bunch of "hair" began to move slowly, and some "terrible" things came out of it...

When you look closely at these hairs, you will find that they are not any plants, but the legs of an animal tightly clustered together.

This creature is called Daddy long-legs , but this name may refer to the arachnid species, the blind spider, or the ghost spider family in the order Araneae. They look very similar because they both have thin and long legs, but the blind spider is not a spider, but an arachnid with eight legs like a spider, and is more closely related to scorpions in terms of classification.

(Readers who are afraid, please imagine a dot + eight thin legs, no need to force yourself to see) | Wiki

Harpy spiders do not spin silk or weave webs like spiders, nor do they have fangs or secrete venom. The second set of legs on their bodies are very long and can act as "sensors" to sense the surrounding environment.

But why do the spiders gather around rocks, and why do they look so much like hair?

Swipe left to see a GIF of blind spiders living in groups (scared readers, please imagine that the stone has hair and the hair moves, no need to force yourself to see it) | youtube

Research shows that many blind spiders may have difficulty surviving the winter, and in the dry autumn, many blind spiders have already begun to try their best to prevent the loss of body water. Therefore, scientists speculate that in order to survive the harsh autumn and winter seasons, blind spiders begin to "huddle together for warmth".

This group of blind spiders may find a shelter in the cracks of rocks or at the exit of a cave, where they gather together to maintain the temperature and humidity needed for survival . At first glance, their long and thin legs really look like hair.

However, scientists have another speculation: such living in groups is actually a means of defense.

For blind spiders, their most effective defense is chemical. They have a scent gland that emits a strong, unpleasant odor that helps them ward off a variety of predators. And when they gather together, the defense is even stronger.

So when the spiders are resting, huddling together in a defensive posture keeps them safer and prevents larger creatures (such as shrews) from attacking them.

Swipe left to see a group of blind spiders (readers who are afraid should imagine blind spiders lined up in a row with many legs, no need to force yourself to see) | Wiki

Although this animal is called "blind spider", it is not actually blind. It has a pair of eyes and can see its prey. However, since it is usually active at night, its eyesight is not very good. And because of this, people have observed that blind spiders will gather on stones when they rest during the day, and at night, the "hair" grown on the stones will disintegrate and go everywhere to look for food.

Swipe left to see an obsidian spider foraging alone (this GIF is still very gentle) | youtube

This kind of group behavior is very common among blind spiders. Scientists have observed hundreds of blind spiders gathering together in Brazil, Alaska and other places. Of course, there are even more exaggerated ones. In 2010, researchers observed a huge group of blind spiders estimated to be 300,000 in Xishuangbanna, Yunnan. Among them, some groups of blind spiders will slowly move and exchange groups.

In Xishuangbanna, researchers also found that this aggregation behavior continued during the dry winter (November to March of the following year) . However, in February, there were only about 3,000 blind spiders in the group. By March, the number of blind spiders had dropped to 1,500 to 2,000. When observed again at the end of April, it was found that all the blind spider groups had disappeared.

In addition to living in groups, blind spiders have other ways to escape, such as special patterns on their bodies that can serve as camouflage in the wild, or bright patterns that can warn attackers. When they are attacked, their bodies can become stiff, or they can voluntarily cut off their legs.

This amazing arachnid appeared as early as 410 million years ago, but there is not much scientific research on them. Ingrid Nixon, an interpreter at Glacier Bay National Park in Alaska, who observed the "hair" on the stone, said: "Nature is full of fascinating surprises that keep us guessing about these amazing phenomena."

If you see one in the wild, don't sit on it...

References

[1]https://threatenedtaxa.org/index.php/JoTT/article/view/498/844

[2]https://www.newyorkalmanack.com/2020/11/daddy-longlegs-during-winter/

[3]https://www.anchoragepress.com/sports_and_outdoors/daddy-longlegs-offer-all-kinds-of-harmless-surprises-to-those-who-pay-attention/article_49463a7a-3b4c-11ec-881b-1ba16f6e4982.html

[4] Glauco Machado, Rafael LG Raimundo & Paulo S. Oliveira IV(2000) Daily activity schedule, gregariousness, and defensive behavior in the Neotropical harvestman Goniosoma longipes (Opiliones: Gonyleptidae), Journal of Natural History, 34:4, 587-596, DOI: 10.1080/002229300299453

[5]https://bioone.org/journals/the-journal-of-arachnology/volume-40/issue-2/Hi11-12.1/Gregarious-behavior-of-two-species-of-Neotropical-harvestmen-Arachnida/10.1636/Hi11-12.1.short

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Source: Bring Science Home (ID: steamforkids)

Editor: Zhong Yanping

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