With the recent events in mind, you should be less worried that you have swallowed spiders in your sleep, and are more likely to worry about avian spiders that rain on your head. As reported in The Guardian recent shots from the Brazilian landscape show thousands of spiders seemingly floating in the air. (Arachnophobes may want to miss the video below.)
In reality, they do not fall at all. The spiders, which are believed to belong to a South American species known as Parawixia bistriata crawl around a tree on an ultrafine and almost invisible web attached to two objects, such as trees or bushes to form canopy.
Why are they doing this? Of course, to catch prey. You will probably catch a variety of insects and perhaps even small birds in their community network, which can be up to three meters wide. (And yes, they also eat the birds.)
The Brazilian biology professor Adalberto dos Santos says The Guardian that P. Bistriata are some of the rare "social" spiders, who do this. They leave their nets overnight, hide in the nearby vegetation and then return to celebrate at dawn.
Although this natural phenomenon is certainly disturbing, it is not exactly rare. The inhabitants of the southeastern town of Espírito Santo do Dourado, where the video was filmed, said that these "spider rain" are common in hot and humid weather.
Here is another video from Santo Antônio da Platina in southern Brazil in 201
It is known that other spider species leap into the wind and "surf" on silk threads to move. They do this to avoid threats or to get food or comrades in other places. Spiderflight cases have been registered worldwide. It's even known that some particularly adventurous spiders cross oceans by "bloating" their way from one land mass to another.
[h/t The Guardian]