In these photos you see three different examples of Argiope sp. that is common to North Central Texas. All are females because of their large size. The photograph above shows an Argiope in the center of her dew-covered web. Notice how large the web is relative to the 3 inch spider (leg tip to leg tip). She is also located in the center of her web which is characteristic of the genus Argiope. The round web is made by members of the Araneidae family, or Orb-
Weavers. Argiope spiders are one of the biggest spiders that can be found in Texas.

The picture below shows a different Argiope sp., on her web, up close. Note the markings on the abdomen and the black and yellow legs.

The last photograph shows another Argiope sp. perched on her refuge in the center of her web and the zig-zag silk structure known as the stabilimentum. A discussion of its function is found in Wikipedia here.

As in much of science, there are puzzles, and lots of conjecture about how to solve them. I wonder if stabilimenta serve more than one of the functions listed in the Wikipedia article in the link above. You may also wish to read the research paper of Todd Blackledge and John Wenzel in Behavioral Ecology found here that discusses some interesting findings. Maybe you will be the researcher who answers this question.

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In the picture above, an Argiope sp. spider is biting a housefly that blundered into its snare. Argiope belongs to Araneidae, the family of orb-weaving spiders. The members of the genus Argiope are large spiders that build large, circular webs in vegetation where flying insects can become caught in their traps. The members of this genus are generally found in the center of their web and are active in the daytime. Because of this, lots of people have become aquainted with these spiders.

In the picture below, the Argiope finishes wrapping its prey for storage. The venom injected earlier not only kills the insect but also digests its insides into a liquid the spider will consume. After wrapping its prey, the spider hangs it near the center of the web and returns to its spot nearby where it will wait for more insects to drop by for dinner.

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Spiders are an old group of Arthropods, they have been around since the Devonian period, some 386 million years ago.

As a group, they have an exoskeleton like insects, but they differ from them in terms of body plan. The head and thoracic region seen in insects is fused to form the cephalothrorax seen in the spiders. The spider body plan is a cephalothorax attached to an abdomen. The 4 pairs of legs and other appendages like their pedipalps and chelicerae are attached to the cephalothorax.

Spiders have several pairs of simple eyes positioned on the anterior end of the cephalothorax. Whereas, insects are distinguished by their compound eyes.

The abdomen of the spiders contains their respiratory, circulatory, digestive and reproductive organs as well as the silk producing structures that also distinguish these creatures from most other species.

As a group, Order Araneae has 113 families and over 45,700 species. They are worldwide in distribution and benefit all ecosystems by controlling the numbers of insects of all kinds. There are spiders that are large enough to feed on small mammals, fish, snakes, lizards, and small birds.

The Family Araneidae, the Orb-Web Weavers is a large and diverse family of spiders with over 169 genera and 3097 species worldwide. In North America, over 31 genera have been identified which encompass over 160 species.

Identifying members of this diverse group to the species level is difficult or impossible from just photographs. Within species, there can be considerable individual variation in the physical characteristics visible in photographs. Microscopic examination in many cases is required; which requires: capturing, killing, and preserving the specimen until it can be examined and measured in the laboratory. I would rather photograph them in their natural habitat and appreciate them for their beauty while being satisfied with characters that I can see. This way the spiders can continue benefiting their ecosystems by controlling insect populations.

The spider pictured above is definitely in the orb-weaver family based solely on the shape of its web. The shape and color of its abdomen looks like some sort of Neoscona while I originally had thought this spider was a member of the Araneus genus. Without the specimen in hand, and a good dissecting scope with a micrometer, and a detailed key; this is about as far as I can take this one.

I went through all this so the budding biologist can get a taste of what is required to “properly” identify some organisms to species. I would also encourage you to examine the huge number of photographs on the internet of Araneus and Neoscona and aquaint yourself with the variety of organisms that may or may not be what they are said to be. As with all things on the internet, verify information you find by consulting books or websites produced by subject matter experts who have examined these creatures in the lab.

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