Test 1 Flashcards
Arthropoda Characteristics
- Bilateral symmetry
- Chitinous exoskeleton
- Segmented body
- Jointed appendages
- Hemocoel, not coelom
- No cilia
- Ventral nerve cord with dorsal brain
Arthropoda is comprised of 3 or 4 subphyla
• Trilobite – extinct (known by fossils) • Chelicerata • Crustae • Atelocerata *crustae + atelocerata = mandibuata*
Tagmosis
grouping of body segments to form functional units
Head + Trunk
Milipedes and Centipedes
Cephalothorax + abdomen
Arachnids and Crustaceans
• Head + thorax + abdomen
Insects
Insect Body
- Head – 3 fused segments
- Thorax – 3 fused segments; primarily for locomotion
- Abdomen – reproduction and digestion
Exoskeleton layers
- Epicuticle
- Exocuticle
- Endocuticle
- Epidermis - only layer with living cells
Exoskelton structures
Pore Canal
Seta
Apodeme
Sulcus
Pore Canal
moves substances from the living cells in epidermis to exterior through non living layers
seta
“hair-like” projections that can be porous for chemical uptake or sensory function
Apopdeme
inward projections where muscle attaches
Sulcus
a groove on the exterior that correlates with the apodeme
Chitin
a nitrogenous polysaccharide
• Fibrils run in parallel to form sheets
• Sheets turned so layers run in different directions
• This adds strength
Sclerotization
irreversible process strengthens exocuticle by crosslinking layers
Soft Cuticle
arthrodial memebrane that lacks exocuticle
• Important for bloodfeeding
• Gravid females and repletes
Four basic types of protuberances or extensions of cuticle:
- Multicellular spine
- Seta
- Acanthae
- Microtrichia
Exoskeleton advantages and disadvantages
• Resists chemicals and pathogens • Resists water loss or gain • Protects from mechanical damage • Provides good leverage for muscles • Used for camouflage and waste storage But... • Restrict growth (molt required) • Limits maximum size
Size Matters
surface to volume ratio
Arachnids
lack antennae, 8 legs, cephalothorax + abdomen, carnivores • Araneae • Opiliones • Acari • Pseudoscorpiones • Scorpions
Crustaceans
branched appendages, calcified exoskeleton (much harder), mandibuletes, biramous appendages, 2 sets of antennae, also two pair of maxillae
Crustaceans - Order
Isopoda - Pill Bugs
Myriapod
• Chilopoda – centipedes
o 1 pair of legs per segment, long antennae, poison claws, predators
• Diplopoda – millipede
o 2 pair of legs (diplosegment), short antennae, repugnatorial glands, feed on decaying vegetation
Insecta characters
- 4 wings
- Segmented body (3) – head, thorax, abdomen
- 6 legs
Insect importance
- Plant community structure
- Nutrient recycling
- Pollination and seed dispersal
- Energy conversion in food web
