1. Arthropods and Their Relatives
Characteristics
Exoskeleton (external covering made of CHITIN)
Molts or sheds exoskeleton to grow
Jointed appendages - Groups very often named in relation to number or type of feet.
Tend to undergo metamorphosis or pass through a number of distinct growth stages during their lives
Tendency toward High degree of cephalization, especially in Class Insecta

2. Arthropods Relative abundance.
3/4 of all known species of animals are arthropods.
More known species of arthropods than known species of plants and animals combined. Great diversity in form and habitat.

3. Major Groups of Arthropods
Subphylum Trilobita - all forms extinct (believed) perhaps some of earliest arthropods
Subphylum Chelicerata - First pair of appendages form chelicera or pincher-like structures used for feeding. 4 pair of walking legs, no antennae. The Arachnida is the only important parasitic group.

6. Major Groups of Arthropods
Subphylum Crustacea - mostly aquatic, most have gills, two pair of antennae. Biramous appendages, meaning limbs have more than one branch. Also have mandibles. Some are parasitic but we will not cover them.
Subphylum Uriramia – single branch or uriramous appendages, mandibles, one pair of antennae

8. Major Groups of Arthropods
Diplopoda - Millipedes - two pair of legs per body segment
Chilopoda - Centipedes - one pair of legs per body segment
Insecta - 3 pair of legs on adults, many with wings, most important group

11. Metamorphosis Simple or gradual three changes adults and nymphs egg
3-5 instars
adult
adults and nymphs
eat same food

12. Metamorphosis Complex or complete four changes larvae and adults egg
pupa
adult
larvae and adults
eat different food
larvae are destructive

13. Fundamental External structure
Insects
3 body regions
head
thorax
abdomen
3 pair legs attached to thorax
1 pair antennae
wings usually present in adult state.

16. Abdomen Thorax Head Hind Wing Fore Wing Antennae Simple Eye
Compound Eye
Jumping Leg
Mouth
Cerci
Palps
Spiracles
Walking Legs
Ovipositor
Abdomen
Thorax
Head

18. Circulatory System Closed circulatory system
Well developed heart pumps blood
Heart is long and narrow
Arteries branch into blood vessels and return blood to the heart via veins – cool, just like us!

19. Excretion Recall the Nephridia in Annelids
The Malphigian Tubules in Arthropods collect nitrogenous wastes in the tubules from blood
Wastes are concentrated (like a kidney does.) Why concentrated?
Excreted out anus

20. Book Gills – folded Gills increase SA for Respiration Horseshoe Crab

21. Respiratory System Gills or lungs, as you’ll see on the next slide 
Organism is too large to rely on surface area. That is, the internal volume is too great to be supplied with oxygen from a minimal SA.

22. Book Lungs are Characteristic of Arachnids

23. Sensory Adaptations Well developed nervous system
Compound eyes with many lenses give Mosaic Vision or multi-images

24. Ultravision – Seeing in the UV Spectrum

25. The Compound Eye
Each crystalline eye generates an image. All images together generate a mosaic effect

26. Simple Eye (Ocelli) Do not form the picture Just gather light
Tell whether it’s light or dark

27. Exoskeleton of Chitin and Muscles attach on Inside

28. How do You Grow Larger if you Skeleton is on the Outside?
Molt, or shed the outer covering

29. External structure of Subphylum Chelicerata, Class Arachnae
Chelicerates have specialized mouthparts called chelicerae – think of the hooked grabbers!
Arachnids (spiders and mites)
2 body regions
Cephalothorax
abdomen
usually 4 pair legs
no wings
no antennae

30. Chelicera = Fangs, for example, on a Spider

31. Chelicerates Include the Horseshoe Crab

32. Body of Arachnids The Spider Body
A spider's body is divided into two parts:
Cephalothorax - Fused head & thorax. The legs are located on the cephalothorax
Abdomen - Similar to that of insects..
                                                                                       

33. Other Members of Phylum Arachnida (4 Pairs of Walking Legs)
Spiders
Ticks and Mites
Scorpions

34. Nature Says Don’t Bug Me with the Colour Red!

35. How Nature Says Do Not Touch