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Citizens’ Environment Watch

Water Quality Monitoring

with Benthic MacroinvertebratesBenthic Macroinvertebrate Identification Guide

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Coelenterata (Hydras)• Size range: 2-25 mm

long• Movement: sessile• Colour: variable, often

clear to whitish• Inconspicuous, tube with

tentacles • Asexual reproduction

through budding

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Turbellaria (Flatworm)• Size range: 5-30 mm • Movement: creep slowly on

bottom • Colour: greyish brown, often ‘colourless’• very flat• unsegmented• eyespots on head

http://www.microscopyu.com/moviegallery/pondscum/platyhelminthes/dalyellia/

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Nematoda (Roundworms)• Size range: usually <1

cm long• Movement: Rapid, whip-

like movements• Colour: usually

transparent• Unsegmented• Usually tapered at both

ends

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Oligochaeta (Aquatic Earthworm)• Size range: 1-30 mm• Movement: crawl along

bottom of tray• Colour: pinkish, light brown• Similar appearance to earth

worm, with bundles of hairs on each segment behind the first

• Segmented body with clitellum (swollen, glandular region)

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Hirudinea (Leech)• Size range: 5-400 mm• Movement: inch along

bottom with the aid of suckers at either end of body

• Colour: brown, black, green on top/orange on bottom

• Segmented body• Often with several

pairs of eyes on head

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Isopoda (Sow Bug)• Size range: 5-20 mm • Movement: crawl slowly

on bottom• Colour: brownish, red• Many pairs of legs (up

to 8)• Dorso-ventrally

compressed• Often associated with

organic matter

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Pelecypoda (Clam)• Size range: 2-250 mm• Movement: none (found at

bottom of tray)• Colour: white, yellow, brown,

grey, black• Hard shell• Flat, 2 halves hinged• Do not count empty shells

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Amphipoda (Scud)• Size range: 5-20 mm• Movement: swim on

side• Colour: blueish grey,

brown, green, red• Many pairs of legs (up

to 14)• Long antennae

http://mywebpages.comcast.net/kils/hyperia/hyperia1.htm

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Decapodae (Crayfish)• Size range: 10-150

mm• Movement: walk on

bottom• Colour: green, brown,

blue• Similar appearance to

lobster• Large claws• Eyes on small stalks• Escapes backwards by

beating tail

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Hydrachnida (Water Mite)• Size range: 0.4-3 mm • Movement: appear like a

small moving dot - uncoordinated, scrambling

• Colour: bright red, green, blue or brown

• Round body• 4 pairs of legs

http://micro.magnet.fsu.edu/moviegallery/pondscum/arachnids/hydracarina/

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Ephemeroptera (Mayfly)• Size range: 3-28 mm (not

including tail)• Movement: Swim up and

down in ‘s’ pattern• Colour: brown or brownish

black (sometimes mottled)• 3 pairs of legs• Single tarsal claw• Feather-like gills under

abdomen• 3 tail filaments (sometimes

only 2 filaments are present)

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Anisoptera (Dragonfly)• Size range: 15-45 mm• Movement: slow• Colour: green to greenish

brown• Larger than mayfly but

without tail filaments; no visible external gills

• Modified labium for catching prey

• Large eyes and head• Often flat

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Zygoptera (Damselfly)• Size range: 10-26 mm• Movement: slow moving but more active than

dragonflies• Colour: green to greenish brown• 3 gills present on end of tail• Thinner than dragonfly• Three pairs of legs

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Plecoptera (Stonefly)• Size range: 5-50mm• Movement: slow• Colour: yellowish,

brown or blackish (sometimes mottled)

• Similar to mayfly but with 2 tail filaments

• Sometimes feather-like gills under body (not dorso-lateral on abdomen)

• Tarsi with 2 claws

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Hemiptera (True Bug)• Size range: 15-40 mm• Movement: swimming or

skimming on water surface• Colour: black or brownish• Legs sometimes long and

stick out from body• Often 2 pairs of soft folded

wings• Often with well developed

breathing appendages• Sucking mouth parts

(rostrum)

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Megaloptera (Helgrammite)• Size range: 25-90 mm• Movement: Crawl on

bottom• Colour: brown• Large, similar in

appearance to centipedes (the ‘hairs’ are actually gill filaments)

• 3 pairs of legs in anterior abdominal segments

• Well developed mandibles• Often with anal prolegs

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Trichoptera (Caddisfly)• Size range: 2-50 mm• Movement: Slow movements

on bottom• Colour: abdomen cream

coloured• Often no movement if found

in cases of sticks, stone or sand (look for heads inside cases)

• Three pairs of legs behind head

• Dorsal thoracic plates variously sclerotized

• Anal prolegs with hooks

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Lepidoptera (Aquatic Moths)• Size range: 10-25 mm• Movement: crawls like a

caterpillar• Head with ring of ocelli

(small simple eye)• 3 pairs of short,

segmented, thoracic legs (between head and abdomen)

• Ventral, abdominal prolegs

http://www.nature.ca/rideau/b/b5b-e.html#synclita

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Coleoptera (Beetle)• Size range: 2-40 mm• Movement: swimming or crawling

on bottom• Colour: brown, black, mottled• Most have 3 pairs of legs near

head• Larvae are similar to caddisfly

larvae but bodies are hard, with mandibles, maxillae, labium and 2- or 3-segmented antennae; may have unsegmented terminal abdominal appendages

• Adults: hardened forewings protect soft hind wings, antennae with 11 or fewer segments

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Gastropoda (Snail)• Size range: 2-70 mm• Movement: none (found

floating or at bottom of tray)

• Colour: grey, brown or black

• Hard shell• Spiral shaped• Do not count empty

shells

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Chironomidae (Midge)• Size range: 2-20 mm• Movement: whip back and

forth• Colour: red, white or

cream• Segmented body• Shaped like letter “J”

when preserved• May be in tube of silt• Well developed, hardened

head with eyes; anterior and posterior parapods (lobed shaped body extensions)

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Tabanidae (Horsefly)• Size range: 1.5-40 mm• Movement: unknown• Colour: white or cream• pointed at both ends, leathery texture• Segmented, straight or slightly curved• 7 pairs of bumps on abdomen (creeping welts with hooks)• Head retracted into thorax

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Culicidae (Mosquitos)• Size range: 3-15

mm• Movement: twitches

when touched• Colour: brown• Thickened body at

head• Segmented body,

curved at one end

http://insects.tamu.edu/images/insects/common/images/b-txt/bimg221.html

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Ceratopogonidae (no-see-ums)• Size range: 3-13mm• Movement: whipping

motion, but stiff when picked up

• Very slender, pointed at both ends, segmented; small pointed sclerotized (hard) head

• No abdominal appendages; may have some terminal abdominal hairs

http://www.junglewalk.com/popup.asp?type=v&AnimalvideoID=3160

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Tipulidae (Cranefly)• Size range: 10-45 mm• Movement: similar to

a worm• Colour: white,

yellowish or light brown

• One end with finger like projection, lobes or long hairs

• Reduced head is retracted into thorax

• Soft body; may have creeping welts

http://www.ent.iastate.edu/imagegal/diptera/tipulidae/3936.94craneflylarv.html

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Simuliidae (Blackfly)• Size range: 3-15 mm• Movement: Similar to an

inch worm• Colour: brown or

greyish• Often with labral fans• Similar to flattened

maggot with one end 1/3 fatter

• Sessile (non-motile), attached at posterior end

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Misc. Diptera (Misc. True Flies)• Size range varies• May have parapods,

pseudopodia (temporary projection), creeping welts or other appendages, but no jointed thoracic legs

• Often maggot-like; head may be retracted into thorax

• Adults with one pair of wings

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References• Images and characteristics adapted from Gartner Lee

Limited, 1997 and Ontario Benthos Biomonitoring Network, 2005

• Commonness rankings from Jacques Whitford Environmental Limited, 2001

• Tolerance values taken from Watershed Report Card, 2000

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Thank You!

For more information, please contact:

Citizens’ Environment Watch401 Richmond St. W. Suite 380

Toronto ON M5V 3A8P: (647) 258-3280F: (416) 979-3155

www.citizensenvironmentwatch.orginfo@citizensenvironmentwatch.org