Phylum Arthropoda: Class Arachnida Flashcards

Class: Arachnida

• Includes scorpions, whip scorpions, spiders, pseudoscorpions, camel spiders, daddy long legs, and mites.

Order Scorpiones (True Scorpions)

• Characterized by pectines, comb-like structures that serve a chemosensory function.

Order Uropygi (Whip Scorpion)

• Notable for its long, whip-like tail; details on specific characteristics are less defined here.

Order Araneae (Spiders)

• Possess a pedicel, a narrow stalk connecting the prosoma (front body segment) and opisthosoma (rear body segment).
• Feature spinnerets, tubular structures that secrete silk for creating webs and cocoons.

Order Pseudoscopionida (Pseudoscorpions)

• Extremely small with large pedipalps.
• They lack stingers, distinguishing them from true scorpions.

Order Sulpugida (Camel Spiders)

• Known as sun spiders or wind scorpions, they are noted for their rapid movements; specific details are not provided.

Order Opiliones (Daddy Long Legs or Harvestmen)

• Body structure consists of a fused prosoma and opisthosoma, creating a rounded appearance.

Order Acari (Mites and Ticks)

• Capitulum serves as the anterior structure containing mouthparts and pedipalps.
• The prosoma and opisthosoma are fused into a single, unified body segment.

Order Acari (Mites and Ticks)

• Exhibit a hypostome, a harpoon-like structure that enables them to anchor to hosts.

Class: Pycnogonida (Sea Spiders)

• Feature a proboscis, a slender tubular extension that ends in an opening.
• Chelicerae are typically reduced or absent.
• Males possess ovigerous legs, specialized appendages for carrying eggs.