Does a spider need a web to catch its prey? Front view of a trap-jaw spider head (family Mecysmaucheniidae) showing pinching mouthparts that snap shut to capture prey the same size or even larger than itself. (Hannah Wood, Smithsonian/Stephanie Stone)
Does a spider need a web to catch its prey?
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What sort of spider can capture its prey without a web?
 
We think of spiders as web-makers. But about half of all known spider species do not make webs. Still, they have organs called spinnerets. Those spin out silk for other uses. Silk can help a spider wrap up its eggs to make an egg case. Or it can line its burrow. Or it can allow the spider to swing to the ground from a branch.
 
All spiders are predators. They sport a huge variety of tactics for capturing their prey. Spiders that do not make webs have other ways to get their meals. A wolf spider hunts down prey and pounces. Then it may use its long legs to straight-jacket it. A fishing spider gets its meal by scurrying over water towards vibrations made by prey. A bolas spider dangles sticky balls made of silk and mucus. The balls are scented to lure in moths. A spitting spider launches a sticky fluid to immobilize its victims.
 
Regardless of their capture technique, nearly all spiders use venom. Once a spider has its prey in hand (actually in its grasping appendages called "chelicerae"), it pierces it with sharp fangs. Then it injects the venom. Spider venom can damage nervous systems or other body tissues. It all depends on the species. But the vast majority of spider venom does not cause harm to humans.
 
One group of spiders with a long name (Palpimanoids) tends to specialize on eating other spiders. What's odd is that the way these spiders capture prey. It may be as complex as their long scientific name. The pelican spider plucks at other spiders' webs. Then it swings its super-long chelicerae outward to pierce them after attracting them over. Another spider in the same group has vice-like chelicerae. These snap shut on its prey with an acceleration that can exceed 1,000 times the acceleration of a space shuttle. Dubbed the trap-jaw spider by Smithsonian entomologist Dr. Hannah Wood, its jaw-like parts look like they are doing splits while they wait in the open position for prey.

Learn more about how spiders capture prey in a live "Smithsonian Science How" webcast on Thursday, January 12, 2017. In "Powerful Predators: Adaptations of Trap-Jaw Spiders" (11 a.m. and 2 p.m. EST on the Q?rius website), Smithsonian scientist Hannah Wood will show you the technology she uses to analyze spider predator adaptations while answering your questions live. You can also get teaching resources to use with the webcast.

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CRITICAL THINKING QUESTION
How do vibrations help a fishing spider?
Write your answers in the comments section below


COMMENTS (167)
  • dylans1-har
    1/04/2017 - 01:25 p.m.

    Vibrations help a fishing spider by telling the spider where their prey is. Ex. a spider is in there web and a fly hit the web and vibrates it that will tell the spider where the fly is. It can also tell the spider if there is a predator comings its way. Spiders can also use vibrations if they can't see. A spider can use vibrations for plenty of things.

  • allisons-kul
    1/04/2017 - 01:56 p.m.

    I had no idea that there were so many differences in spiders. Previous to reading this article, I had no knowledge about fishing spiders or spiders that pounce. Vibrations help the fishing spider because the vibrations may confuse its prey or cause it to go into shock which makes them weak. When the prey is weak, the fishing spider is able to attack it.

    • bethanyl-kul
      1/05/2017 - 01:39 p.m.

      I agree with Allison, i didn't know there are so many different types of spiders. I think that it is very interesting how these different types of spiders hunt.

    • coltonw-kul
      1/05/2017 - 04:04 p.m.

      I knew that there were quite a few spiders, but did you know that some can even walk on water and are really fast, but thankfully their bite is not lethal.

    • garyttt-kul
      1/24/2017 - 04:56 p.m.

      You are correct about vibrations helping spiders, but I don't think you quite know how. The vibrations come from the prey, not the spider. The vibrations are what allow the spider to locate its prey.

  • coltonw-kul
    1/04/2017 - 02:24 p.m.

    First off, I hate spiders, a lot. Although I think it is kind of cool that they have so much venom in their tiny bodies. But, to the story, I really don't care that spiders can catch prey in other ways as long as I am not the thing that it is biting.

    • allisons-kul
      1/05/2017 - 01:46 p.m.

      I am totally with you Colton, I HATE SPIDERS!! To me, it is absolutely crazy that one little spider with venom has the power to affect thingsseverely. And again, I am with you on the not caring part as long as they don't bother me.

    • jennav-kul
      1/05/2017 - 03:16 p.m.

      I agree I am not a fan of spiders at all. I also agree that it doesn't really matter how they catch the prey because it doesn't affect my life in any way.

    • codyp-kul
      1/08/2017 - 12:50 p.m.

      I agree with you Colton. I hate spiders too. I do also think it is cool that they have that much venom in their bodies.

    • sages-kul
      1/08/2017 - 10:45 p.m.

      though spiders don't bother me very much I do agree with Colton, it is really cool how much venom a spider can store in there body.

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