1. Intro to Arthropods

2. 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

3. 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.

4. Major Groups of Arthropods
Subphylum Trilobita - all forms extinct (believed) perhaps some of earliest arthropods

5. Major Groups of 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 group.
Other examples of Chelicerates: horseshoe crabs, sticks, scorpions

6. Chelicerates Include the Horseshoe Crab

7. 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.
Examples of Crustaceans:
Pill bugs, crabs, crayfish, lobsters

8. Major Groups of Arthropods
Subphylum Uriramia – single branch or uriramous appendages, mandibles, one pair of antennae
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. 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.

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

15. 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

16. 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..
                                                                                       

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

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

19. How Nature Says Do Not Touch

20. Feeding and Digestion
-Arthropods can be herbivores, carnivores, and omnivores.
-They can be bloodsuckers, filter feeders, detritivores, or parasites

21. Feeding and Digestion
Their mouthparts range from pincers to fangs to sickle-shaped jaws

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

24. Respiratory System
Some arthropods have a network of branching tracheal tubes that extend throughout the body. Air enters and leaves the tracheal tubes through spiracles (small openings located along the side of the body)
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.

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

26. Book Lungs are Characteristic of Arachnids

27. Circulatory System Open 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!

28. 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.)
Excreted out anus
- In aquatic arthropods, cellular wastes are diffused into the water

29. Response and Sensory Adaptations
Well developed nervous system – brain!
Have nerve cords connected to ganglia that coordinate the movements of legs and wings
Compound eyes with many lenses give Mosaic Vision or multi-images

30. Ultravision – Seeing in the UV Spectrum

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

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

33. Movement Arthropods have muscles coordinated by the nervous system
Different muscles flex or extend the joint, pulling on the exoskeleton

34. Exoskeleton of Chitin and Muscles attach on Inside

35. Reproduction Terrestrial arthropods: internal fertilization
 male places sperm in female
 male deposits sperm packed that is picked up by female
Aquatic arthropods: internal OR external fertilization

36. Metamorphosis Simple or gradual three changes adults and nymphs egg
Lack adult structures
adult
adults and nymphs
eat same food

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

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

39. Today’s task
In your groups, summarize and present one of the following topics.
Make sure to include labelled diagrams and key terms!
Groups 1 + 2: Crustaceans (pp )
Insects and Relatives (p.725)
Groups 3 + 4: Spiders and relatives (pp )