00:00You've probably seen spiders catch insects that are smaller than they are in
00:04their sticky webs. But did you know that there are some spiders that can catch
00:08prey that's much larger than they are? And they do it by wrapping them in sticky
00:13strands of web and lifting them off the ground.
00:21Now scientists have known about this behavior for some time, but it hasn't
00:25been very well studied. So for the first time a group of scientists took
00:29several of these spiders and observed them doing this prey lifting behavior
00:35under laboratory conditions. The spider built this web. In the connection
00:39between the main frame of the web, which is the part dense of threads, and the
00:45surface below, the spider spin these threads. And these threads are actually
00:52the feature that sends signals to the spider that something is hitting, something
00:58is passing below. So the elastic energy stored in the frame, which is basically
01:05we have to think about an elastic, you know. So if you pretension an elastic, it will
01:10recall with an elastic force. If the prey is small, so just one thread is necessary to lift it.
01:16Unfortunately, when the prey is big, of course the one thread is not necessary, but this is what
01:24actually poses a challenge to the spiders. The logic is exactly the same as before. So the spider
01:30produces thread as elastic and it pretensions them. Then it attaches this thread to the prey. And this is pretty
01:39cool, because it's one of the few cases
01:42where the spider is actively involved in the hunting by means of the web.
01:48It's no more a trap, a passive trap, in the sense that the web works perfectly as it is, but
01:54the spider is getting involved too.
01:57Because normally the spiders are just sitting and waiting for the prey that enters the web.
02:03And that's it. As you can see, the structure of this web is particularly complicated. There are different types of
02:10silk.
02:11So each part of the web has its own silk for that specific function. These are the supporting threads.
02:19And as you can see, there are two types of threads. Two threads in these supporting threads. One thread is
02:25produced by a gland.
02:27The other one is produced by another gland. The very same thread, but this thread is coated with these droplets
02:36that are produced by another type of silk.
02:39And we have three types of silk. Where the spider joins together these threads, it uses this kind of cement
02:46-like silk,
02:48which is another type of silk. So four different types of silk are used to produce this frame.
02:56It also wraps the prey because it has also to mobilise locally the prey in order to avoid the prey
03:02to move too much.
03:03And it uses another type of silk to wrap it. Normally material scientists go crazy with this because the spider
03:11is a perfect factory of silk.
03:13It produces multifunctional materials in less than milliseconds, each one optimised for that property.
03:21So it's crazy. They are like machines. They are super efficient.
03:27And there are like 49,000 different species of spider. Each one produces different type of silk with different properties
03:37up to the species, up to the individual.
03:39So basically, we do not know nothing about silk.
03:41When you start studying in-depth things, you realise that you don't know anything about them.
03:46And I don't know, we use two species of spider, but there are other species of spider, as I said
03:51before, that must be investigated from this point of view.
03:54There are also other type of prey that may behave differently.
04:00So this was just the first insights in this direction, but there are tons of possible questions that can be
04:07answered.
04:08So even though scientists now have a better idea as to how the spiders are able to trap large prey
04:15and actually lift it up off the ground,
04:18there are still a lot of unanswered questions about how exactly the spiders make all these different types of silk,
04:25and what are the limits of how they can use them.
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