Ref: ITIS 82708 (http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=82708) 2002-09-18
The arachnids, Arachnida, are a class of invertebrate animals in the subphylum Chelicerata. They are chiefly terrestrial arthropods, some 65,000 to 73,000 species including the spiders, scorpions, harvestmen[?], ticks, and mites.
Arachnids are mostly carnivorous, feeding on the body juices of insects and other small animals. Many are venomous - they secrete poison from specialized glands to kill prey or enemies. Others are parasites, some of which are carriers of disease. Arachnids usually lay eggs, which hatch into immature adults.