Transcript Body regions

Bi 212, Lecture 5
Phylum Arthropoda
Phylum Arthropoda:
“jointed foot”
Evolutionary relationships
and HOX genes
Basic Arthropod Features
Paired, jointed appendages
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Functions: Locomotion; feeding; protection
joints allow for flexibility
Segmentation
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Some: segments all similar
Most: segments combined into specialized body regions
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Example: Insects have 3 regions: head, thorax and abdomen
Exoskeleton
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Key material: chitin
Same materials also in mouthparts, wings, eye lens
Key function of exoskeleton?
Exoskeleton is molted
Focus on Molting
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Function: growth
New exoskeleton built under old
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Risks
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How is this possible, since new exoskeleton
is larger than the old one?
Strategy of female crabs to reduce risk…
Some arthropods continue to molt
and grow throughout their lives.
Subphylum Crustacea
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Lobsters, crabs, shrimp, barnacles,
copepods, etc..
Subphylum Crustacea
 Antennae
 How many pairs?
 Body regions
 Cephalothorax & abdomen
 Calcium carbonate in
exoskeleton
 Gills
 Compound eyes
 Feeding modes
 Lobsters and crabs
 Barnacles
 Krill!
Antarctic krill
Euphausia superba
Subphylum Unirama
(Hexapoda & Myriapoda)
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Insects, centipedes, millipedes
 Three distinct body
regions
 Name them!
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Head capsule
Single pair of antennae
Compound eyes
Feeding modes
(examples)
 Chewing (wasp)
 Piercing/sucking
(giant water bug)
Photos: www.microscopy-uk.org
Dennis Kunkel
Subphylum Chelicerata
(Cheliceriformes)
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Spiders, mites, scorpions, horseshoe crabs
 Antennae
 How many pairs?
 Body regions
 Cephalothorax & abdomen
 Eyes: type?
 Specialized feeding
structures
 Pedipalps
 Chelicerae
 Sucking stomach
Body plan
Feeding/Digestive system
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Modes of feeding in different groups (already discussed)
Complete
Circulation/gas exchange
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Open circulatory system
Respiration structures and systems
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Crustacea: gills
Uniramia: tracheal system. CARRIES OXYGEN AND CO2
Chelicerata: tracheal system, book gills and book lungs
Body plan
Water/ion balance and ammonia excretion
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Crustacea: gills and antennal (or “green”) glands
Uniramia and Chelicerata: Malpighian tubules
Nervous system
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Brain (=cerebral ganglia)
Ventral nerve cord (paired, fused)
Ganglia: one per segment or fewer (consolidated)
Body plan
Reproductive systems
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Usually internal fertilization
Spermatophores
Sperm storage
Reproduction
 Internal fertilization
(many)
 Spermatophores
 Sperm storage
www.livescience.com
Photo: www.guclehmann.de