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A friend recently asked for some tips how to identify spiders.

jumping-spider-another1. Leg size and position

Often the length and position of the legs are easy to see and can give you a clue. Jumping spiders like this one have short legs that are tucked up under their bodies.

 

flower-spider

Crab spiders have 2 pairs of long front legs. They hold their front legs out to the side with the tips directed forward.

feather-legged-spider-1

Feather-legged spiders also have extra-long front legs. They hold their first pair of legs directly out front of themselves and pressed together.

wolf-spider-23Wolf spiders have legs that are all roughly the same length and shape, as do a few other groups such as fishing spiders.

2. Web pattern

Some spiders are easier to identify by their webs.

garden-spider-orbOrb weavers (also called garden spiders) produce large complex webs, often across paths.

funnel-web-retreatFunnel web spiders produce sheets of silk around a central, hollow retreat.

3. Eye Pattern

If you can get a good photograph from the front of the spider, the size and position of the eyes can aid in identification.

Let's take a quick look at spider anatomy, in case you are not sure which is the front end.

basic-spider-anatomy

Besides the legs, the other parts you see on the spider are the abdomen (body area covered with red arrows), and the combined head and thorax, called the cephalothorax (body area covered with yellow arrows). The two appendages that surround the mouth are the pedipalps. The pedipalps are at the front end of the spider, with the eyes.  (Note:  in newer scientific texts the abdomen may be called an opistosoma and the cephalothorax called a prosoma).

The eye patterns are distinctive and easy to recognize with a bit of practice.

jumping-spider-face-viewLooking face on at a jumping spider you can see they have two large eyes in the front of their cephalolthorax and two smaller eyes on either side.

jumping-spider-side-view-general

They also have two smaller pairs of eyes further back. See the dark, shiny eye about 1/2 way back on the cephalothorax?

crab-spider-on-purple-100In contrast, the crab spiders have a cluster of tiny eyes right in a oval at the top and front. The eyes in this spider are set into the orange-yellow colored area. You can hardly see the eyes in comparison with those of the jumping spider.

Eye_Arrangement_of_a_Wolf_Spider

(Photograph by Thomas Shahan from USA licensed under the Creative Commons Attribution 2.0 Generic license at Wikimedia.)

Wolf spiders also have two large central eyes, but have a downward-curving row of four eyes below them. They also have another pair further back, which you can just see as a dark curves.

This is only a very basic introduction to spider identification. If you would like to learn more about this, BugGuide has set up an excellent page showing all the different eye patterns in spiders.

Spiders have quite a bit going on and are actually quite fascinating once you get to know more about them.

2

We have some new spiders in our yard. Even if you don't like spiders, you should bear with me on this one, because it is so cool.

First, the spider has a typical orb web, shaped rather like a plate.

See that yellowish blob on the upper right? That is also part of this spider's web, about two or three inches behind the orb.

Here's a shot from the side. See the bridge of webbing from the orb to the place where the spider sits?

That pile of debris has a fancy name. It is called a stabilimentum. Early investigators named it that because they thought is was part of the support structure of the web, a web "stabilizer."

In this closer view, you can see the bridge and stabilimentum more clearly. The yellow cotton parts are acacia flowers from a nearby tree. (This web is in a desert willow).

While taking photos of the orb web, a mosquito flew into the web. The spider was there in no time flat.

It quickly pulled the mosquito out of the web. It must have subdued the mosquito somehow, but the action was too quick for me to see what happened.

The spider took the mosquito back to the stabilimentum immediately and hung it amongst the other debris.

How did the spider get back and forth so quickly? Take a close look at the web and see if you can guess.

Okay, now some of you sharp-eyed folks might have noticed something else about the stabilimentum from the photographs above.

From another angle, you can see the "main" spider is still at the bottom, but there's a second, smaller spider sitting behind and to the rear.

Any ideas why it is there?

In any case, I don't know what kind of spider this is, although my best guess is Cyclosa or a near relative. Can anyone help me out?