1. 1 Arachnids Dale Taylor Advanced Life Science Rainier Jr/Sr High School

2. 2 Arachnids One “branch” of Subphylum Chelicerata –Have chelicerae: modified mouthparts Includes fangs and pincers –Other “branches” of Subphylum Chelicerata include Sea spiders Horseshoe crabs

3. 3 Arachnids Include many common organisms –spiders –scorpions –ticks –mites –daddy long-legs (harvestmen) –and many more

4. 4 Arachnids Are MAJOR insect predators Most have venom, very few affect humans –Only two species of spiders in the US are venomous to humans Black widow Brown recluse

5. 5 Arachnids Have 2 body segments –cephalothorax –abdomen Appendages –first set called chelicerae (fangs or pincers) –second set called pedipalps are used to catch, handle, and chew prey also have some sensory functions

6. 6 Arachnids Have 2 body segments –cephalothorax –abdomen Appendages –Next come 4 sets of walking legs (8 total) Have no jaws, must liquefy prey and lap up the remains. Leaves only an empty exoskeleton behind.

7. 7 Arachnids SPIDERS –Have poison glands on chelicerae poison used to stun or kill prey –Spinnerets at caudal end of abdomen produce silk for webs, egg baskets, etc –Some have 8 eyes: 2 moveable, 6 stationary.

8. 8 Arachnids SCORPIONS –S–Stinger on end of abdominal extension used to stun prey –P–Pedipalps enlarged Tong-like action used for grasping and defense

9. 9 MITES –T–The largest arachnid group Mites, chiggers, ticks –H–Head, thorax, and abdomen are fused together –A–Are common pests usually not deadly, just VERY irritating Ticks are a common vector for diseases –L–Lyme disease, Rocky Mountain Spotted Fever –E–Ehrlichiosis, Tick Paralysis, etc.