Transcript Aquatic Insects

Aquatic Insect Orders
Aquatic Insects
• Insects are largely
terrestrial.
• But there have been
numerous colonizations
of the freshwater
aquatic environment.
• Far fewer colonizations
of marine aquatic
environment.
Aquatic Insects
• Some lineages have
almost* exclusively
aquatic naiads.
– Ephemeroptera
– Odonata*
– Plecoptera
• All of these have
terrestrial adults.
Ephemeroptera
• Naiads often with
abdominal gills
– Also maxillary and
labial gills!
• Generally 3 styli on
naiads and adults.
• As many as 45
instars
• Anything else?
Odonata
• Dragonflies &
Damselflies
• Rectal/anal internal
gills.
• Caudal lamellae
also serve as gills.
• Up to 20 instars.
• Predators as naiads
and adults.
Plecoptera
• Mostly temperate
regions
• 10-33 instars
• Closed tracheal
system with anal
gills.
• Need high oxygen,
good environmental
indicators.
Hemiptera:
True Bugs
• Diving or at surface
• Adults and naiads both
aquatic.
• Highly modified legs.
• Generally wings still
functional as adults, can
disperse between
waterways.
Gerridae:
Water striders
Notonectidae:
Backswimmers
Corixidae:
Water Boatmen
Naucoridae:
Creeping
water bugs
Hemiptera
• Left: Nepidae (water scorpions) tails are breathing
tubes
• Right: Belostomatidae (toe-biters) egg tending by
males
Trichoptera
• Case & net makers.
• Abdominal tracheal gills.
Coleoptera
• Aquatic larvae,
aquatic adults
• Aquatic larvae,
terrestrial adults
• Terrestrial larvae,
aquatic adults
• Pretty much all
pupate on land
Diptera
• Often with anal
spiracles breathing
at surface
• Very diverse
• Almost all disease
vectoring Diptera
have aquatic larvae
(?)
Megaloptera & Neuroptera
Open tracheal system in flies
• Respiratory siphons near abdomen or thorax
• Different location in mosquito pupa than larva
How do aquatic insects obtain oxygen?
• Atmospheric oxygen
– Keep part of body out of
water
– Carry oxygen into water
• Aqueous oxygen
– Specialized tracheal
systems
Tracheal System
Closed Tracheal System
• Gills- lamellar
extensions of tracheal
system
• Found in many insect
orders
• Gills may be in many
places
–
–
–
–
Base of legs
Abdomen
End of abdomen
How is this analogous to
insect ears?
Open tracheal system in diving beetles
• Bubble stored beneath elytra
• Gas exchange can occur in water
Other air bubble gills
• Water kept away from body through ‘hairs’ or ‘mesh’
• Oxygen diffuses from water to air against body
• Usually slow moving insects with low oxygen demand
Lotic Adaptations
• Flattened bodies
• Attachment through suckers
Water pennies (Coleoptera: Psephenidae)
Net-winged midges
(Diptera: Blephariceridae
More Lotic Adaptations
• Nets & Cases
Trichoptera net
Trichoptera cases
Lentic Adaptations
• Taking advantage of surface
tension of still water
Water Strider (Gerridae)
Whirligig Beetle (Gyrinidae)
Adaptations to nearly anoxic environments
• Hemoglobins
– Many larval chironomid midges (Diptera) = bloodworms
– Very, very high affinity for oxygen (unlike us)
Using insects to monitor aquatic environments
• Usefulness
– Diverse taxa to choose from, many common
– Functionally important to ecological community
– Ease of sampling many individuals without major
ethical constraints
– Ability to identify species
• Responses
– Increases of certain taxa in waters with sediment,
low
– Oxygen, increases in temperature
– Loss of diversity with pollution and or
eutrophication