Arachnids (Class Arachnida) are invertebrate animals in the Phylum Arthropoda that have an exoskeleton, a two-part segmented body, and eight jointed legs. The body is divided into the prosoma (cephalothorax) and the opisthosoma (abdomen). The prosoma contains the mouth and acts as the site of attachment for the chelicerae (mouthparts), pedipalps (variously modified appendages), and four pairs of legs and associated musculature. It also contains the brain (neural ganglia), pharynx, stomach, and eyes (when present). The opisthosoma contains most of the organs of the digestive, circulatory, reproductive, and respiratory systems including the midgut, heart, ovaries or testes, and book lungs. They are ectothermic (cold-blooded).

The Class Arachnida contains the following orders:

Araneae: True Spiders, Tarantulas, Trapdoor Spiders

Scorpiones: Scorpions

Thelyphonida: Whip Scorpions, Vinegaroons

Amblypygi: Tailless Whip Scorpions

Solifugae: Sun Spiders, Wind Scorpions, Camel Spiders

Opiliones: Harvestmen, “Daddy Longlegs”

Pseudoscorpionida: Pseudoscorpions

Schizomida: Whip Scorpions with divided exoskeletons

Acari: Ticks and Mites

Palpigradi: Micro Whip Scorpions

Ricinulei: Hooded Tickspiders

Haptopoda: Extinct

Phalangiotarbida: Extinct

Trigonotarbida: Extinct

Arachnids are gaining in popularity and availability as pets. Many are low maintenance and inexpensive to keep. Many can be captured around the house or yard, depending on location, while a growing assortment of native and exotic arachnids can be found at many local pet stores. Most of the arachnids kept as pets come from the orders in bold print the above section. Occasionally, someone will capture and attempt to keep species from some other orders (especially Solifugae) with limited success. On the other hand, mites from Order Acari can become a very difficult pest to exterminate from an owner’s prized collection of tarantulas and scorpions.

S

• Scorpions‎ (3)

T

• Tarantulas‎ (3)
• ► True Spiders‎ (1)

W

• ► Whip Scorpions‎ (1)