insect body plan and exoskeleton. phylogeny myriapoda chelicerata hexapoda crustacea (crabs,...
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INSECT BODY PLAN AND EXOSKELETONINSECT BODY PLAN AND EXOSKELETON
PHYLOGENY
Myriapoda
Chelicerata
Hexapoda
Crustacea (crabs, lobsters, barnacles)
Pauropoda
Diplopoda (millipedes)
Chilopoda (centipedes)
Arachnida (spiders, mites, ticks)
Eurypterida (sea scorpions)
Xiphosura (horseshoe crabs)
Pycnogonida (sea spiders)
Trilobita (trilobites)
Symphyla
Mandibulata
Arthropoda
?
Arthropod Lineages
Insect Body Plan
Tagmata
Head Thorax Abdomen
6 segments- sensory & feeding
3 segments- locomotion
-11 segments- digestion & reproduction
Total of 20 segments (primitively)
Insect Body Plan
Tagmata
Head Thorax Abdomen
Cross section
pleuronpleuron
tergum (notum)
sternum
Insect Body Plan
pleuronpleuron
tergum (notum)
sternum
Note: The bits of exoskeleton (the pieces in the puzzle) that make up the outer surface of an insect are collectively referred to as sclerites.
Each surface of an insect has its own sclerites which are referred to as tergites, sternites and pleurites.
Insect Body Plan
Segments
1) Primitive Condition (annelids, larval insects)
intersegmental fold
longitudinal muscle
primary segment primary segment primary segment
Insect Body Plan
Segments
2) Intermediate Stage (hypothesized)
intersegmental sclerite
longitudinal muscle
primary segment primary segment primary segment
segmental sclerite
Insect Body Plan
Segments
3) Third Stage (seen in Apterygota)
primary segment
secondary segment
4) Final Stage (seen in Pterygota)
phragma
Insect Integument (Exoskeleton)
Why are insects crunchy?
Outer epicuticle
Inner epicuticleEpicuticle
Exocuticle
Endocuticle
Schmidt’s layer
Epidermis
Basement membranePore canals
Procuticle
Insect Integument (Exoskeleton)
Why are insects crunchy?
Outer epicuticle
Inner epicuticleEpicuticle
cement
waxoriented wax
cuticulin
Inner epicuticle
Exocuticle (procuticle)
pore canal
Insect Integument (Exoskeleton)
cement
waxoriented wax
WATER WATER
Wax Layers - Control of Water Movement
WATER IS RETAINED
Structure of Chitin - Albert Hoffman (1906 – 2008)
Insect Integument (Exoskeleton)
NH
O = C - CH2
CH2OH
O
NH
O = C - CH2
O
N - acetylglucosamine polymer
OH H
H
OH
H
H
O
CH2OH
H
H
OH H
n
Insect Integument (Exoskeleton)
CO
NH CO
NH CO
NH CO
NH CO
NH CO
NH
CO
NH CO
NH
CO
NH CO
NH CO
NH CO
NH
hydrogen bonds
NH
O = C - CH2
CH2OH
O
NH
O = C - CH2
OH H
H
OH
H
H
O
CH2OH
H
H
OH H
Insect Integument (Exoskeleton)
N - acetylglucosamine polymer
microfibril
sheets of microfibrils
orientation of microfibrils changes
Insect Integument (Exoskeleton)
Protein Matrix
Insect Integument (Exoskeleton)
Cross linking of protein matrix
Insect Integument (Exoskeleton)
OH
Cross linking of protein matrix
OH
C
CH2
Protein Protein
OH
OH
CH2
CH2
O
O
CH2
CH2
OH
OH
CH2
CH2
Protein Protein
N-acetyl dopamine N-acetyl dopamine quinone
What other common material has cross-linked fibres in a matrix?
Plywood PlywoodPlywood Oriented Strand Board (OSB)Plywood
Insect Integument (Exoskeleton)
Tensile strength of sclerotized chitin (sclerotin)
kg/mm2
Some days you’re the bug,some days you’re the windshield.
- Mark Knopfler