Cellar Spiders Attack & Capture Prey at 1,000fps

Added: 2026-05-31

[00:00:00]Look to the middle of the frame, and hanging  by a thread, that’s a fruit fly. It’s a common household nuisance, and the thread it’s hanging  on was put there by the cellar spider that you see approaching from the left, it’s one of  the most common household predators on earth.

[00:00:16]Now, I don’t usually work with spiders and there  hasn’t been a spider video on this channel yet.

[00:00:21]But, recently, we’ve been capturing some  interesting and dramatic high-speed footage, like what you see now, of these spiders in action.

[00:00:29]And while I don’t know much about spiders,  what I’ve seen in this footage is teaching me a lot and kind of blowing my mind about  what these spiders are what they can do.

[00:00:41]OK, so before we dive into that footage. Let  me show you just how common these spiders are.

[00:00:46]The closest thriving population of them that I  have access to is actually 5 floors below this lab, in the museum’s underground parking garage. In the garage, they’ve made nearly every pipe and light fixture the home base for their cobwebs.  This cellar spider, Pholcus phalangioides, is sometimes also called a house  spider or daddy long-legs spider and is thought to be a cave-dwelling species  and now they’ve spread all across the globe by living in human-built cave-like environments. So, after finding them, to start filming and working with them, a student Elias and I brought  them into the lab and set them up in small box where they could construct their webs and we could  offer them a steady supply of fruit flies as prey.

[00:01:26]We quickly figured out that we needed  to film up-close and in slow motion, if we wanted to see anything in detail about  how prey capture and silk deployment works.

[00:01:36]In this clip, you’re seeing what prey capture  and wrapping an insect in webbing looks like in real-time. It’s a flurry of blurred  motion that transforms a snagged fly into a tightly wrapped and cocooned  prey item in a matter of seconds.

[00:01:49]Here’s what the end result looks like for  that fly. I’m impressed by how thorough of a wrapping job they do. The entirety of the  fly’s body is wrapped in more or less an even coating of the webbing to where no part of the  body is sticking out of able to move freely.

[00:02:03]So now I want to show you how these  spiders do that, in up-close detail.

[00:02:07]All this footage is new ground for  me, and what you’ll see next are my favorite sequences that reveal  how these spiders capture prey In this clip, you’re seeing the spider  do its first approach to its prey.

[00:02:18]Cellar spiders produce different types of silk, so  the fly here could be either tangled and snagged or glued to a sticky bit of web. With its  front leg, the first thing the spider does is grab the thread that’s attached  to the the fly and hold in position.

[00:02:32]And then, instead of biting it attacks the fly  with silk. The spider’s long legs keep the prey item at a distance, while it wraps it up to both  restrain it and further secure it to the web.

[00:02:44]Now the part that I was really impressed by  seeing was how the cellar spider deploys its silk.

[00:02:50]It uses it’s hind legs to grab and pull the  threads out of the spinnerets. Now the silk is microscopically thin which made it hard to see  and catch on video, but every time it catches the light in this shot you can see how each pull  is composed of multiple strands. The back legs alternate, left-right-left-right to pull the silk  and place it around the prey. In this sequence, which I filmed at 1,000 frames per second, the  spider is averaging 8 silk-pulls every second.

[00:03:18]Next, I wanted to see how the legs were handling  the silk and putting it around the prey, so I got a series of super up-close shots to try  to see just that. What these clips show is that the spider hooks a whole sheet of webbing across  the length of the last segment of its leg. With one leg, the spider drapes these threads on top of  the prey item while the other hind leg below grabs the threads and pulls them up to the other side. The part of the hind leg that is handling the silk is the last segment, called the tarsus. Here’s what the hind tarsus looks like up close.

[00:03:50]It’s covered in comb-like hairs and ends in a  longer tarsal claw. They use that tarsal claw, which is on the end of each of their  legs, to grab and hang on to their web.

[00:04:01]The tarsal claw doesn’t seem to be  what’s used to pull out the silk threads.

[00:04:05]Instead the comb-like hairs that line the  rest of the tarsus hook onto the silk threads when they’re pulled up and also release the  threads when the legs are pulled back down.

[00:04:14]These silk-wrapping threads are sticking to each  other partially due to a spider-produced glue, as evidenced recently, when researchers  imaged these prey wraps and saw globs of glue between the tangled mass of fibers. After the prey item is wrapped, then the spider goes in for venom injection, which you can see  happening here. Feeding happens after this, only after the prey has been secured in a silk  wrap and incapacitated through a venomous bite.

[00:04:40]Now this is all just one way that these particular  spiders catch prey. They also lay sticky lines of silk down to the substrate, called gumfoot lines,  to capture things moving around on the ground.

[00:04:51]And i’ve also read that they can leave their  webs to hunt, sometimes targeting other spiders.

[00:04:56]Of course, there’s a lot more to their biology  and behavior than what I’ve been able to capture and show in the video. But, even with these  bits of footage, I think my perspective and appreciation for these spiders has changed  and I hope yours has too. Thanks for watching.