PPT Slide
- Among spiders, the cephalothorax and abdomen shows no external segmentation; tagma are joined by a narrow pedicel
- Respiration is accomplished via book lungs, tracheae, or both
- Usually have 8 simple eyes; at the very least they detect motion; for some of the predatory forms, they are capable of forming crude images
- Many species have evolved poison glands associated with the chelicerae