1. Arthropoda

2. Classification

3. Arthropods Adapted to aquatic and terrestrial environments
Probably first animals on land and in air
Most diverse animal phylum

4. Segmentation Pair of appendages per segment Fused segments – tagmata
Reduced number for most arthropods
Specialized – locomotion, feeding, defense…
Fused segments – tagmata
Head, thorax, abdomen

5. Exoskeleton Composition Advantages
Chitin – cross-linked polysaccharides
Protein and lipids
Calcium salts – very hard
Advantages
Protection
Muscle attachment
Joints
Wings

6. Exoskeleton – Laminated Structure
Epicuticle
Protein and lipids
Procuticle
Exocuticle
Secreted before molt
Endocuticle
Secreted after molt

7. Ecdysis

8. Respiration Terrestrial – trachea (network of breathing tubes)
Aquatic – gills
High oxygenation = high metabolic rate

9. Sense Organs Compound eye Antennae Ommatidia Tactile, chemosensitive
Photoreceptors
Lens
Pigment cells
Nerve fiber
Antennae
Tactile, chemosensitive

10. Compound Eye

11. Subphylum Chelicerata
No mandibles – mostly suck food
Two tagmata
Cephalothorax
Abdomen
Six pairs of appendages
1 pair chelicera
1 pair pedipalp
4 pair walking legs

12. Class Merostomata Limulus Horseshoe crab Unsegmented carapase
Book gills
Spike-like telson

13. Class Arachnida Spiders, mites, scorpions, ticks
Terrestrial and marine
Chelicera often develop into fangs or pincers
Most feed by sucking fluid from prey or host
Specialized organs
Excretory system - Malpighian tubles
Allows conservation of water
Book lungs or book gills

14. Order Araneae Spiders Poison gland
Digestive enzymes injected into prey
Malphigian tubules
4 pairs of simple eyes
Sensory setae

15. Araneae Anatomy

16. Reproduction
Dioecious – male and female
Eggs laid in silk cocoon

17. Web Silk Silk glands at posterior end Made of protein
Solidifies when it hits the air
Very strong
Silk glands at posterior end
Spinnerets – help manipulate the growing silk strand

18. Subphylum Crustacea Mostly aquatic 2 Antennae, maxillae and mandible
Biramous appendages
Chelipeds – often enlarged to form claws

19. Crustacean Body Plan

21. Uniramia Key Features Legs do not branch Specialized feeding mandibles
Tracheal system of gas exchange
Malpighian tubules
Single pair of antennae

22. Uniramia Classes
Diplopoda
Millipedes
Chilopoda
Centipedes
Insecta

23. Diplopoda Fused segments Two pairs legs per segment
Eat vegetable matter

24. Chilopoda
Pair of legs per segment
Predator
Poisons prey

25. Insecta Over one million species Found all over the world
Not found in marine environment – dominated by crustaceans
Structural Features
Tagmata – head, thorax, abdomen
Legs only from thorax
Wings

26. Insect Flight Muscles

27. Figure-8 Pattern Upstroke Downstroke Leading edge faces up
Leading edge faces down

28. Flight Muscle Control Synchronous Asynchronous
One impulse = one stroke
Dragonflies, butterflies
Asynchronous
One impulse = multiple strokes
Flies, bees, midges

29. Basic Anatomy

30. Respiration and Circulation
Tracheae
Network of tubules
Open to outside – Spiracles
Branch into fine tracheoles
Supported by bands of chitin
Open circulatory system
Haemocoel filled with haemolymph

31. Digestive System Foregut Midgut Hindgut
Mouth, esophagus, crop, gizzard
Grinding and storage
Midgut
Stomach and gastric ceca (increases surface area)
Digestion and most absorption
Hindgut
Intestine, rectum, anus

32. Excretion Malpighian Tubules Extensions off of the intestine
Project into the haemocoel
Exchanges waste with haemolymph

33. Metamorphosis Holometabolous Complete – example: butterfly
Egg  Larva  Pupa  Adult
Many larval tissues disintegrate during pupa stage

34. Metamorphosis Hemimetabolous Partial – example: roach
Egg  Nymphs  Adult
Nymphs are similar to adults