Respiratory Adaptations of Aquatic Insects in WetlandsRespiratory Adaptations of Aquatic Insects in Wetlands
Christine L. GoforthGraduate Student,
EntomologyFall 2002
Christine L. GoforthGraduate Student,
EntomologyFall 2002
Introduction
Insects first evolved on land with a terrestrial respiratory system
Insects are secondarily adapted to aquatic habitats, so have to adapt their gas-filled respiratory system to the aquatic environment
Insects first evolved on land with a terrestrial respiratory system
Insects are secondarily adapted to aquatic habitats, so have to adapt their gas-filled respiratory system to the aquatic environment
Terrestrial Respiration
Insects have a gas-filled respiratory system Terrestrial systems have large internal surfaces, but few external openings
maximize oxygen uptake, minimize water loss
Insects have a gas-filled respiratory system Terrestrial systems have large internal surfaces, but few external openings
maximize oxygen uptake, minimize water loss
Air vs. Water
Air and water are very different respiratory environments:
Oxygen diffuses 324000 times more slowly in water than air!Oxygen saturated air = 200000ppmOxygen saturated water = 12-15 ppm at best
It is very difficult for insects to get sufficient oxygen from the water
Air and water are very different respiratory environments:
Oxygen diffuses 324000 times more slowly in water than air!Oxygen saturated air = 200000ppmOxygen saturated water = 12-15 ppm at best
It is very difficult for insects to get sufficient oxygen from the water
Open vs. Closed Systems
There are two main groups of respiratory adaptations:
Closed – all spiracles are sealed and non-functional; indirect respirationOpen – at least some spiracles are still functional; direct respiration
There are two main groups of respiratory adaptations:
Closed – all spiracles are sealed and non-functional; indirect respirationOpen – at least some spiracles are still functional; direct respiration
Closed SystemsClosed Systems
No open spiracles…No open spiracles…
Cuticular Respiration
Closed systemOxygen diffuses directly through exoskeleton into the tracheal system
Thinned cuticleRich tracheation immediately below surface
Uncommon in wetlandsEg. Black flies
Closed systemOxygen diffuses directly through exoskeleton into the tracheal system
Thinned cuticleRich tracheation immediately below surface
Uncommon in wetlandsEg. Black flies
Gills
Closed systemOxygen diffuses through cuticle at extensions of the exoskeleton especially adapted for oxygen transfer
Plate-like structures on abdomenRich tracheation in gills
Uncommon in wetlandsEg., damselflies
Closed systemOxygen diffuses through cuticle at extensions of the exoskeleton especially adapted for oxygen transfer
Plate-like structures on abdomenRich tracheation in gills
Uncommon in wetlandsEg., damselflies
Open SystemsOpen Systems
Some spiracles functional…
Some spiracles functional…
Atmospheric Breathers
Open systemRequires access to surface so that air may be taken out of the atmosphere rather than the water
Hydrofuge hairs prevent drowning
Common in wetlandsEg., water scorpions
Open systemRequires access to surface so that air may be taken out of the atmosphere rather than the water
Hydrofuge hairs prevent drowning
Common in wetlandsEg., water scorpions
Plant Breathers
Open systemWorks like atmospheric breathing, but taps into aquatic plants as its oxygen sourceNot a very common adaptation in any aquatic system, but does occurs most in vegetated areas like wetlandsEg., aquatic weevils
Open systemWorks like atmospheric breathing, but taps into aquatic plants as its oxygen sourceNot a very common adaptation in any aquatic system, but does occurs most in vegetated areas like wetlandsEg., aquatic weevils
Gas Film Respiration
Open systemUse atmospheric gasses that are carried on the insect by special hairsTwo main types:
Physical gill – temporaryPlastron - permanent
Common in wetlandsGas films act as gills
Open systemUse atmospheric gasses that are carried on the insect by special hairsTwo main types:
Physical gill – temporaryPlastron - permanent
Common in wetlandsGas films act as gills
Air = 21% O2, 78% N2, <0.1% CO2
Water = 35% O2, 64% N2, <0.1% CO2
AirO2
O2N2