How spiders catch their prey
Spiders use a multitude of techniques to capture prey. Most people will be aware of web building spiders and hunting spiders, but there other techniques spiders use which include ambushing and even fishing.
Spiders build different kinds of webs based on their species. Spider webs come in many different forms including; orb webs, tangle webs and sheet webs. Webs are used as an extension of the spiders sensory systems. Orb weavers usually have very poor eye sight, but there sense of touch is very powerful. Orb weavers can differentiate between prey, wind and even predators touching their webs. This is usually quite good, but the predatory spider Portia fimbriata is good at exploiting this to feed on orb weavers. Webs allow spiders to catch prey without the risks associated with direct contact and can easily be rebuilt when they get broken.
Hunting spiders use a more direct approach to catching prey and this too comes in a multitude of forms.
Wolf spiders are common worldwide and a good example of direct hunting. They wander around in their environment and will jump on prey when they see it, they will also chase prey over short distances. Jumping spiders have great eyesight, doing a Google image search of jumping spiders will show how big they are in proportion to their bodies. These spiders can see prey almost perfectly up to 30 cm. They can watch their prey and track them down using various hunting methods. Portia fimbriata is one of the closest animals to showing invertebrates to be capable of cognitive tasks. Portia while hunting can mimic dead leaves, sometimes having prey items trying to hunt under it. It can enter webs of spiders much bigger than itself and skillfully attack and kill the host. When it sees a prey it demonstrates object permanence by being able to leave and find better ways to approach without directly risking being caught by its prey, including abseiling onto it from above.
Ambush hunting or crypsis
Many spiders do not go out and directly hunt their prey, they sit and wait. This can be using trap doors, which they sit and the door of and wait for vibrations of insects to come by then they spring out and catch them and dart back to the safety of their burrow. Ant mimics are the most common kind of salticid, these spiders look like ants, but all so mimic chemical cues which allows them not to be attacked by ants. These spiders can easily prey on ants while not worrying about other predatory spiders which rightfully fear ants. Many crab spiders blend into their flower based backgrounds and catch unknowing insects. Don’t instantly assume that this camouflage will protect them from predators as they are easily seen under UV light, which many of their predators can see in. Crab spiders associated with pitcher plants will wait at the bottom for much larger prey to fall in the pitcher and drown, before eating them. These crab spiders found in pitcher plants will also feed of larvae that live in pitcher plants.
The bolas spider is known as an aggressive mimic. This spider lays out a line of sticky silk and swings it around in front of itself. Whilst doing this it emits pheromones similar to female moths, this attracts male moths who think that they may have found a mate. These male moths fly right into the swinging silk making an easy meal for the spider.
I have barely even touched on the basics of how spiders catch their prey. Each method of capture requires a full length article in their own respect to give them justice. Spiders are interesting complex animals with many interesting life histories. Spiders are truly one of the world’s ultimate predators.