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Lentic
still (non-moving) freshwater
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Benthic
associated with bottom substrate (vs water column)
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Limnetic
well-lit zone, open surface waters in lentic waters away from shore
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Littoral
zone near the shore area where sunlight reaches to the sediment and allows aquatic plant growth
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Lotic
environments with fresh, flowing water
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lotic orders
1st order streams are origin point. Two 1sts join to make a second, two seconds make a third, etc.
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headwaters (lotic)
1st to 3rd order of a lotic system
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small rivers
4th to 6th order lotic habitat
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large rivers
7th to 12th order
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hyporheic zone
region beneath and along side of a stream bed
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heterogeneous components of lotic habitats:
hyporheic zone (region beneath and long side of a stream bed), main channel, slackwaters, flood plains
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Where do insects occur in lotic habitats (invert diversity is highest in lotic habitats)
A few in the water column, but more abundant in photic/littoral zone and benthos
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Abiotic zones within lentic habitats
- -Aphotic zone
- -Photic zone
- -Limnetic zone
- -Littoral zone
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Air/water interface
neuston
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Which three orders make up most of the freshwater invertebrates in the hyporheic zone?
While all freshwater invert phyla have representatives in this zone, it is mainly Diptera, Coleoptera, and Ephemeroptera.
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Characteristic of cave systems
- -simple food webs
- -low species diversity
- -high levels of endemism
- -food comes from outside source
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stygofauna
animals that only live in groundwater (mostly beetles)
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Marine environments
- -mainly home to semi-aquatic insects
- -mud flats, rock pools
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Caddisfly marine adaptation
- -make homes out of coral, shell, seaweed
- -can even lay eggs in coelum of starfish
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Open ocean colonizers
Halobates water striders
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what can colonize puddles of crude petroleum
brine flies: larvae are predacious and rely on atmospheric oxygen
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Why do insects need O2?
Needed for cellular respiration; O2 is the last electron acceptor in mitochondrial reactions that release energy from digested food molecules
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How do insects obtain O2?
Spiracules allow air in, then it enters a trachea then tracheoles
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What decreases the amount of oxygen that can be dissolved?
- -increased temperature
- -increase in salinity
- -increase in altitude
- -increase in depth of water
- -low wind conditions
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Diffusion moves gases through respiratory surfaces; what variables affect the speed of gas movement?
- -molecular weight of gas
- -permeability of medium
- -concentration gradient
- -distance
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Where does oxygen diffusion occur in insects?
- -Across membranes and cuticular surfaces
- -between tracheoles and tissue cells
- -along tracheal tubes
- -between water and the insect body
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spiracles
segmentally arranged lateral pores
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tracheae
- -cuticular ingrowths that branch internally from spiracles
- -tracheoles branch off
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Open tracheal systems
- -insects that breathe air
- -spiracles must contact air
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Baetiscidae/armored mayfly
- -pools/runs in sandy streams
- -1 genus local
- -enlarged notum
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Ephemeridae/burrowing mayflies
- soft silt/sand rivers/lakes
- mandibular "tusks"
- fringed gills (1-7) held over abdomen
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Caenidae/small square-gill mayflies
- slow streamsgills on 2 operculate
- operculate gills protect functional gills
- can tolerate salt
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Ephemerellidae/spiny crawler mayflies
- flowing waterscollector/gatherer
- No gills on 2
- gills not forked or fringed
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Leptophlebiidae/prong gilled mayflies
- gills on 1 slender
- gills on 2-7 FORKED not fringed
- some with tusks
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Baetidae/small minnow mayflies
- small swimmerslakes, ponds, slow streamslabrum with notch
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Ameletidae/Combmouthed Minnow Mayflies
- monotypic
- swimmer like Baetidae
- short antennae
- Pectinate spins on maxillae
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Isonychiidae/Brush-legged mayflies
- monotypic (Isonychia)
- live in swift currentscollectors/filterers medium sized swimmers
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Siphlonuridae/primitive minnow mayflies
- swimmers
- maxillae without pectinate spines
- gills OVATE
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Flathead mayflies/Heptageniidae
- live in flowing water, on rocks etc. (very common)scrapers
- gills 1-7
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