Lecture 14 Flashcards
Aquatic insects represent an integral part of ____ & ___ food webs
aquatic & terrestrial
In the food chain, aquatic insects are included in _____ production
secondary
What 8 orders include the bulk of aquatic insects?
o Mayflies o Dragonflies & damselflies o Stoneflies o Bugs (Heteroptera) o Alderflies, fish flies & dobsonflies o Caddisflies o Beetles o Flies
which 3 orders have the most diversity?
Bugs, beetles & flies
what are the 3 common life histories observed in aquatic insects?
- Those with an aquatic juvenile & a terrestrial adult stage (leave water to mate & lay eggs)
- Those that spend most of all of their life in the water (adult & juveniles are aquatic)
- Those that spend the majority of their life in close assoc with water (semi-aquatic insects) – don’t live in the water but are closely assoc
what are exs of insects with an aquatic juvenile & a terrestrial adult stage (leave water to mate & lay eggs)
♣ Ex: mosquitos
♣ Ex: dragonflies & alderflies
♣ Ex: mayflies
what are exs of insects that spend most of all of their life in the water (adult & juveniles are aquatic)
♣ Ex: water boatmen
♣ Ex: giant water bugs
♣ Ex: aquatic beetles
what are exs of insects that spend the majority of their life in close assoc with water (semi-aquatic insects) – don’t live in the water but are closely assoc
♣ Ex: waters stridders
♣ Ex: some aphids (live on lily pads)
♣ Ex: round sand beetles
Variation in the _______ & _______props of aquatic habitat has shaped the evolutionary history of aquatic insects
physical & chem
what are the 2 forms of aquatic habitats?
lentic or lotic
lentic habitat & exs
still waters
any circulation of water is due to wind
exs: lakes, ponds, wetlands
lotic habitats & exs
flowing waters
exs: streams, rivers
All extant aquatic insects evolved from ______ ancestors
terrestrial
describe insect evolution
evolved from terrestrial ancestors. Made the transition from terrestrial habitats to aquatic multiple diff times in dif grps.
Has lead to many adaptations to overcome obstacles
aquatic insects evolved from ancestors with an ____ respiratory sys
air filled
why is it inefficient for insects to live in aquatic habitats>?
much less oxygen in water than in air
what is the largest obstacle faced in evolution for aquatic insects
obtaining sufficient oxygen in aquatic habitats
describe the respiratory adaptation of passive diffusion
insects are small (SA:V)
decres size = decres oxygen requirements
activity limited by oxygen
describe the respiratory adaptation of breathing tubes
Spiracles have a connected breathing tube to remain connected to the surface
(must remain near the surface of the water)
what are 3 exs of insects that have breathing tubes?
mosquito larvae, aquatic bugs (water scorpion), water tiger
describe the respiratory adaptation of biological gills
flat portions of the cuticle forming gills that increase the SA of the body
apart of tracheal sys
increases the amount of o2 they can consume
what type of insects use biological gills?
when living at the bottom of a body of water
what are exs of insects that have biological gills?
mayfly nymph
stoneflies
caddisflies
describe the respiratory adaptation of physical gills
temporary air bubbles, obtain & hold pockets of air, breathe air from an air bubble while underwater
make bubble with hydrophobic hairs
As the insect consumes oxygen, the concentration of oxygen will be smaller in the bubble than in the water
causes passive movement of O2 & N
describe the respiratory adaptation of plastron
permanent air bubble maintained by a dense layer of hydrophobic hairs
what insect uses physical gills?
waterboatmen
what does a plastron enable insects to do?
permanently live under water
what insect has a plastron?
aquatic beetle
describe the respiratory adaptation of hemoglobin
hemolymph contains hemoglobin that can retain & release oxygen on demand
what is the most efficient adaptation for extracting oxygen from water?
hemoglobin
what are the forces that aquatic insects need to overcome when living in moving wateR? (3)
o Friction/viscosity
o Current
o Surface tension
buoyancy control & ex
use to adjust positioning in the water column
Ex: Phantom midge – juveniles have air bubbles that through muscular contraction can expand or reduce to control their buoyancy
walking on water & ex
Provide enough resistance that they can generate thrust to move
Ex: water striders – presence of dense brush of hydrophobic hairs causing repellency & prevent tarsi to break through surface tension of water
how do insects swim? & exs
pair of swimming legs with a stiff pair of hairs
Ex: wriggly beetles
Ex: mayflies - move like a fish
Ex: backswimmers - have modified hind legs with stiff hairs
why is it necessary for insects to prevent moving in water?
at risk of being moved to an unsuitable habitat
rock hugging
Don’t swim, assoc with bottom substrate
Suction cups assoc with each abdominal & thorax segment, attaches to rocks & moves slowly along them
flat bodied
when water is flowing over rocks, the velocity of the current rapidly approaches 0 when going closer to the rocks
a flat-bodied insect is the function of the _____ _____
boundary layer
burrowing & ex
burrow into the ground to remove themselves from the current
ex: mayfly
case building & 2 exs
many cases act as rocks to weigh them down to prevent movement
ex: bloodworm
Ex: caddisflies - silk cases
how do insects prevent movement from water?
rock hugging
flat-bodied
burrowing
case building
Aquatic insects are typically classified into ‘functional grps’ based on their______ & ______
diet & mode of feeding
shredders & 2 exs
eat coarse particulate matter (CPOM)
make fine particulate matter available to other insects to consume
ex: cranefly water
ex: caddisflies
collecter & filter feeders & 2exs
feed on fine & ultra fine particulate matter
Filter feeders – live in an envr where there’s a current constantly providing food
ex: blackflies & caddisflies
scrapers & grazers & 3exs
feed on biofilms, algae or any organic layer that forms on the surface of logs, rocks etc.
ex: mayfly, stonefly, some caddisflies
predators
feed on other aquatic arthropods
ex: dragonfly nymph
describe how dragonfly nymphs feed?
breathe through gills at the rectum, pump water in & out of the rectum for respiration
Have a valve that they can close to control water movement
Lower lip is expandable that they can fire forward to obtain prey – close valve at the rectum, squeeze abdomen & the lower lip fires outwards
