1. Subphylum Chelicerata

2. Characteristics
Six pairs of appendages besides mouth (second pair are usually pinchers)
The first pair of appendages are the chelicerae (feeding appendages).
Lack antennae
Lack mandibles (mouthparts)
The body is divided into two distinct regions, the prosoma (head and thorax) and the opisthosoma (abdomen).

3. Arachnids
Have a pair of chelicerate as their foremost appendage-can be pinchers
Over 85% are spiders or mites
Palps - a second pair of appendages are used to catch and handle prey.
The palps are followed by four pairs of walking legs- 8 total

4. All Arachnids are carnivores They have no jaws
They ingest only liquid food- thus they digest food externally
Usually use enzymes to break down food source
Mostly terrestrial

5. Scorpions Large front pincers Venomous stinger on tail
Holds tail over body as it walks
First animal to successfully invade land
Fossil scorpions over 425 mya

6. Scorpions cont… nocturnal active at night
Live in tropical warm climates
Only a few are venomous to humans
Young crawl onto mothers back after born-where they remain for 1 month- if they fall off mother eats them

7. Spiders
Have poison glands that secrete toxins through chlicerae that has become fangs
Use fangs to bite and paralyse prey
Many use webs to trap prey
Some sense prey on web due to motion
Has eight legs and usually eight eyes

8. Some Poisonous Spiders
Brown Recluse
Black Widow

9. Mites Chiggers and ticks All the body segments are fused together
Usually fed on other animals

10. Mite Example Dermatophagoides spp (Bed /Dust Mites)
Bed mites feed on the scales which are continually falling from our skin.
Dust mites favor homes with high humidity levels and constant warm temperatures.
Many live in high traffic areas in homes and on certain furniture items, especially beds, upholstered lounges, chairs, and in carpets with long fibers.
Nearly 100,000 mites can live in one square yard of carpet.
Big cause for human allergies

11. Ticks

12. Ticks
Ticks are blood feeding external parasites of mammals, birds, and reptiles throughout the world.
Important vectors of disease causing agents to humans and animals throughout the world.
Lyme disease is an infection caused by bacteria which is carried by deer ticks.
Lyme disease to the nervous system can cause the face to droop

13. Homework
What characteristics of arachnids prepare them for terrestrial environment.
What makes a Chelicerata a Chelicerata?
Compare ticks and spiders.