Spiders are invertebrate animals¹ that produce silk², have eight legs³ and no wings ⁴. More precisely, a spider is any member of the arachnid order Araneae⁵, an order divided into three sub-orders in newer systems: the Mygalomorphae (the primitive spiders), the Araneomorphae (the modern spiders) and the Mesothelae, which contains the Family Liphistiidae, rarely seen burrowing spiders from Asia ⁶. The study of spiders is known as arachnology, although it is often grouped under the more general area of entomology.

Many spiders hunt by building webs to trap insects⁷. These webs are made of spider silk, a thin, strong protein strand extruded by the spider from spinnerets on the end of the abdomen⁸. All spiders produce silk, although not all use it to spin elaborate traps⁹. Silk can be used to aid in climbing, forming smooth walls for burrows, cocooning prey, and for many other applications.¹⁰

1 Statement: "Spiders are invertebrate animals"

• "Arthropods include insects, crustaceans, and arachnids, such as spiders". Encyclopedia Article: Invertebrate. Microsoft Encarta Encyclopedia 2003.
• "Invertebrate Zoology Section Spiders". Website: Milwaukee Public Museum
• "Invertebrate Animals Arachnids" Mexico for Kids

2 Statement: "that produce silk"

• "produce silken threads and webs" Encyclopedia Article: Spiders (Arthropod). Microsoft Encarta Encyclopedia 2003.

3 Statement: "have eight legs"

• "spiders have eight legs" Encyclopedia Article: Spiders (Arthropod). Microsoft Encarta Encyclopedia 2003.

4 Statement: "no wings"

• "they lack antennae and wings" Encyclopedia Article: Spiders (Arthropod). Microsoft Encarta Encyclopedia 2003.

5 Statement: "a spider is any member of the arachnid order Araneae"

• "Spiders belong to the order Araneae" Encyclopedia Article: Spiders (Arthropod). Microsoft Encarta Encyclopedia 2003.

6 Statement: "spider silk, a thin, strong protein strand"

• see: http://www.sciencenews.org/pages/sn_arc98/2_21_98/fob2.htm