Bi 212, Lecture 5

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Bi 212, Lecture 5

• Phylum Arthropoda

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Phylum Arthropodajointed foot
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Evolutionary relationships
and HOX genes
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Basic Arthropod Features

• Paired, jointed appendages
• Functions Locomotion feeding protection
• joints allow for flexibility
• Segmentation
• Some segments all similar
• Most segments combined into specialized body
  regions
• Example Insects have 3 regions head, thorax
  and abdomen
• Exoskeleton
• Key material chitin
• Same materials also in mouthparts, wings, eye
  lens
• Key function of exoskeleton?
• Exoskeleton is molted

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Focus on Molting

• Function growth
• New exoskeleton built under old
• How is this possible, since new exoskeleton is
  larger than the old one?
• Risks
• Strategy of female crabs to reduce risk
• Some arthropods continue to molt and grow
  throughout their lives.

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Subphylum Crustacea

• Lobsters, crabs, shrimp, barnacles, copepods,
  etc..

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Subphylum Crustacea

• Antennae
• How many pairs?
• Body regions
• Cephalothorax abdomen
• Calcium carbonate in exoskeleton
• Gills
• Compound eyes
• Feeding modes
• Lobsters and crabs
• Barnacles
• Krill!

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Antarctic krillEuphausia superba
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Subphylum Unirama(Hexapoda Myriapoda)

• Insects, centipedes, millipedes

• Three distinct body regions
• Name them!
• Head capsule
• Single pair of antennae
• Compound eyes
• Feeding modes (examples)
• Chewing (wasp)
• Piercing/sucking (giant water bug)

Dennis Kunkel
Photos www.microscopy-uk.org
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Subphylum Chelicerata (Cheliceriformes)

• Spiders, mites, scorpions, horseshoe crabs

• Antennae
• How many pairs?
• Body regions
• Cephalothorax abdomen
• Eyes type?
• Specialized feeding structures
• Pedipalps
• Chelicerae
• Sucking stomach

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Body plan

• Feeding/Digestive system
• Modes of feeding in different groups (already
  discussed)
• Complete
• Circulation/gas exchange
• Open circulatory system
• Respiration structures and systems
• Crustacea gills
• Uniramia tracheal system. CARRIES OXYGEN AND
  CO2
• Chelicerata tracheal system, book gills and book
  lungs

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Body plan

• Water/ion balance and ammonia excretion
• Crustacea gills and antennal (or green)
  glands
• Uniramia and Chelicerata Malpighian tubules
• Nervous system
• Brain (cerebral ganglia)
• Ventral nerve cord (paired, fused)
• Ganglia one per segment or fewer (consolidated)

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Body plan

• Reproductive systems
• Usually internal fertilization
• Spermatophores
• Sperm storage

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Reproduction

• Internal fertilization (many)
• Spermatophores
• Sperm storage

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Photo www.guclehmann.de