Phylum Arthropoda, class Arachnida, order Araneida (or Araneae) is the general term for all species of spiders. They are distributed worldwide except for Antarctica, from sea level up to altitudes of 5,000 meters. All are terrestrial. Their body length ranges from 1 to 90 millimeters. Spiders are both beneficial and harmful to humans, but they are primarily considered beneficial insects due to their contributions. The body length of spiders varies from 0.05 millimeters to 60 millimeters. Their bodies are divided into the cephalothorax and abdomen. Some species have a carapace on the dorsal side of the cephalothorax. The front end of the cephalothorax usually has 8 simple eyes (though some may have 6, 4, 2, or none), arranged in 2 to 4 rows.
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