FW zoobenthic groups we will talk about: An incomplete tour of the meio and macrobenthos

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FW zoobenthic groups we will talk about An
incomplete tour of the meio- and macro-benthos
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What do you do when you find an unknown
invertebrate a) squish it b) call Homeland
Security Department c) use a dichotomous key to
identify it
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Within-Lake Zones
High benthos density diversity
low benthos density diversity
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Annelida Oligochaeta
Bilaterally symmetrical Segmented each segment
with chaetae (little hairs/bristles)
http//www.inhs.uiuc.edu/sjtaylor/cave/oligochaet
a.html
Hermaphroditic sexual and asexual reproduction.
Usually paratomy (budding) also create cocoons
filled with embryos. Widespread many habitats
and trophic levels Some specie used as pollution
indicators- very tolerant Bioturbators
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Specialty area to identify characters hard to
see Difficult to count because they break easily
http//www.unice.fr/LEML/coursJDV/_private/phyl1.h
tm
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Annelida Hirudinea (leaches)
60 spp in USA Dorsoventrally flattened
segmented Mouth surrounded by oral sucker large
caudal sucker Can be very colorful colors fade
in preservative
Glossiphoniidae- scavengers or predators Piscicoli
dae- fish parasites Hirudinidea-parasites Haemopid
ae-carnivores or parasites
Different feeding modes
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Only 2 common U.S. genera (Macrobdella and
Philobdella) that attack humans
Attach with caudal sucker and explore with
anterior end. 3 fine painless incisions made by
back and forth rotary motion of jaw Sufficient
blood taken so that leach may be 5 times original
mass Leech leaves voluntarily but host may
continue to bleed due to anticoagulant
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Can be common Most scavengers or predators on
small inverts Can be important food source for
insect larvae fish like them too Used to
support large industry in Europe during 18th and
19th centuries for medicinal purposes Hirudo
medicinalis raised in ponds in large numbers (has
been introduced to NA several times but
unsuccessful) http//www.nytimes.com/2006/02/07/s
cience/07leec.html
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http//www.nanfa.org/akiweb/658.JPG
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Famous invertebrates from Hollywood!
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Arachnida Hydrachnidia water mites
Look like tiny spiders 8 legs Most carnivorous
or parasitic Separate males and females Can be
very abundant in weedy areas usually found in
shallow waters Beautiful colors (fade w/
preservative) Hard to identify
http//images.google.com/imgresimgurlhttp//test
.dnr.nsw.gov.au/care/wetlands/facts/paa/invertebra
tes/images/water_mite_eylais.jpgimgrefurlhttp//
test.dnr.nsw.gov.au/care/wetlands/facts/paa/invert
ebrates/watermites_aquaticspiders.htmlh338w400
sz20hlenstart14sig2eKOanf2HjZpwetS9dOHqEA
tbnidMqsx3hWcSPtdEMtbnh105tbnw124eiOQEiR5a
dKaeceMq70KICprev/images3Fq3Dwater2Bmite26gb
v3D226svnum3D1026hl3Den
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Phylum Mollusca (Life in a shell)
100000 spp. Gastropods-snails
slugs Bivalves- clams/mussels Cephalopoda
(squids octapus cuttlefish nautilus-
marine) Higher taxonomy messy
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You name it some gastropod does it
70 of all mollusks marine freshwater and
terrestrial habitats. About 500 species in the
freshwaters of North America north of
Mexico 350 prosobranchs (derived from
marine) operculum gills 150 pulmonates
(derived from terrestrial) lungmodified mantel
cavity
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Valvata bicarinata
Campeloma decisum
Physella/Physa spp.
http//members.aol.com/mkohl1/FWshells.html
picture source
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Bivalves
NA bivalve fauna most diverse in word Unionoidea
278 spp Corbiculacea 36 native and 4
introduced Dreissenoidea 2 spp (zebra and
quagga mussels) (more later)
superfamilies
Mucket
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Crustaceans
Specious abundant and ecologically important
35000 species mostly marine some fw
terrestrial -anatomically diverse--fused
segments or specialized appendages -important
trophic component of many systems
Crustaceans have
-2 pairs of antennae -most body segments bear
paired jointed appendages -all crustaceans go
through a free nauplius stage or show evidence of
an egg-nauplius stage
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Crustaceans you should know
Order Anostraca fairy shrimp
elongate distinctly segmented temporary pools
or very saline habitats (e.g. brine shrimp
Artemia salina) either sexual or parthenogenic
eggs thin-walled summer eggs hatch quickly
thick-shelled winter eggs withstand heat cold
desiccation. swim on backs by beating
appendages also serves to obtain food such as
phytoplankton bacteria protozoans rotifers and
detritus.

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http//www.cdpr.ca.gov/docs/es/esgifs/fairy.gif
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Order Ostracoda seed shrimp segmentation lost
opaque bivalve carapace feed mostly on bacteria
molds algae detritus large spp. may eat dead
animals eggs may remain dormant for long
periods tolerate wide range of ecological
conditions some tolerate anoxia in some spp.
advanced instars can bury in mud to survive
desiccation and cold.
http//www.kulak.ac.be/facult/wet/biologie/pb/kula
kbiocampus/insecten-ongewervelden/vijverfauna/zoop
lankton/Ostracoda/Ostracoda202.jpg
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Order Isopoda (superorder Pericarida aquatic sow
bugs) most spp. marine or terrestrial 130 f.w.
spp. in N.A. flattened dorsoventrally scavengers
males carry females before mating waiting for
pre-adult exoskeleton shed
bilateral copulation (e.g. first one side then
the other) after mating female sheds anterior
half of exoskeleton so that brood chamber plates
are functional fertilized eggs and young stay in
brood chamber young find their way out the
posterior end by trial and error.
http//www.iii.to.cnr.it/limnol/bentos/foto/Asellu
s_aquaticus.jpg
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Order Amphipoda (superorder Pericarida
scuds) laterally compressed crawl or
swim respiration through gills usually benthic
some dart into pelagic zone
omnivorous scavangers will eat dead animals
leaves organic debris and graze surface
films male carries female until she molts
(amplexus) they separate briefly and re-join to
copulate shortly thereafter the female ovulates
and oviposits eggs and developing young reside
in the marsupium young are released at the
females next molt
http//www.nativefish.org/Gallery/other/Gammarus-s
p..htm
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Order Decapoda crayfishes and shrimp most spp
marine body and appendages strongly
sclerotized compound eye stalked movable head
and thorax fused and covered by carapace walk
or climb with periopods when alarmed quickly
dart backward using tail fan omnivorous
scavangers including snails plant material and
occasionally sponges
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Males cannot distinguish males females so turn
over every crayfish encountered during mating
season. If he got lucky and the female is
receptive mating will proceed. Female lays eggs
several weeks after copulation first she cleans
her ventral side with tips of pereiopods
secretes sticky substance (glair) into which
sperm and eggs are mixed she carries developing
eggs on ventral surface young leave at third
instar many crayfish burrow but propensity to
do so varies some spp. live in wet fields with
no open water
http//www.nativefish.org/Articles/StFrancis.htm
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Fresh water Insects
When J. B. S. Haldane a British geneticist was
asked what his studies of nature revealed about
God he replied An inordinate fondness for
beetles.
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5 aquatic orders almost all spp have aquatic
larvae
Ephemeroptera Trichoptera Odonata Megaloptera Ple
coptera
5 partially aquatic orders most species are
terrestrial but some spp have aquatic life stages
Heteroptera Lepidoptera Coleoptera Neuroptera Di
ptera
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Ephemeroptera mayflies
675 spp Streams and littoral areas of
lakes Important fish food
Usually 3 caudal filaments Abdominal gills
http//www.waterbugkey.vcsu.edu/php/orderdetails.p
hpidnum8
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Larvae leave water and molt into subimago stage
(unique among insects) Fly to vegetation spend
day before molting to adult Adults do not
feed Females oviposit usually at water surface
Mating swarm near Sandusky River
Collecting females at Windsor
http//www.heidelberg.edu/depts/wtr/krieger.html
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Odonata
Anisoptera dragonflies Zygoptera damselflies
434 spp Most larvae in lentic (lake or slow
water) habitats Larvae large and
predatory Elongate hinged labium 1-6 yrs
http//www.youtube.com/watchvA9Q8gUTmyd8feature
related
http//www.naturewatch.ca/eman/reports/publication
s/99_montane/odonata/odonatafig06.html
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http//www.entomology.umn.edu/museum/links/coursef
iles/Odonate20characters.html
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Adults predatory live several weeks Complex
mating behaviors including mate guarding

http//www.naturewatch.ca/eman/reports/publication
s/99_montane/odonata/odonatafig06.html
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Plecoptera stoneflies
614 spp Most common in fast cold
streams Larvae predators 2 long tail
filaments Long antennae Larvae crawl rather
than swim Adults live days to weeks
http//www.weeksbay.org/newsletter/Sum_2003/Pg8_1.
htm
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Trichoptera Caddisflies
http//www.wildscape.com/earrings.asp
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1400 spp Lotic lentic Adults terrestrial and
easily identified but many larvae unknown Some
build silk nets to catch prey Some free living
predators Some build cases Ecologically varied
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Can be dominant in streams Many fish feed on
larvae Can have large hatches
http//www.epa.gov/bioindicators/html/caddisflies.
html
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Megaloptera fishflies and alderflies
7-8 lateral filaments (O2 uptake) large
mandibles Can be confused with Coleptera
Adults large secretive terrestrial Lentic
larvae have caudal respiratory tubes Larvae are
predators
Corydalidae
http//www.epa.gov/bioindicators/html/photos_inver
tebrates.html
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5 aquatic orders almost all spp have aquatic
larvae
Ephemeroptera Trichoptera Odonata Megaloptera Ple
coptera
5 partially aquatic orders most species are
terrestrial but some spp have aquatic life stages
Diptera Lepidoptera Coleoptera Neuroptera Hetero
ptera
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Diptera flies midges
Many families and spp Differ greatly in ecology
(habitat feeding.) Only larvae are aquatic
Lack segmented thoracic legs Trophic importance
in many systems Some vectors of disease (e.g.
mosquitoes)
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Chironomidae midge larvae ( 2000 spp)
Very important fish food Wide range of ecology
http//www.biol.wwu.edu/407/407/Crustaceans.html
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Tipulidae cranefly larvae
http//alpaca.cs.umb.edu/gallery/Aquatic-Invertebr
ates/tipulidD_thm
Chaoboridae phantom midge larvae Pelagic
predators
http//www.iii.to.cnr.it/limnol/bentos/cauborus.JP
G
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Coleoptera beetles
Only 3 of beetles have aquatic stage (still many
spp!) 1450 in NA Spp w/ aquatic larvae and
adults
http//www.ru.ac.za/academic/departments/zooento/M
artin/elmidae.html
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water pennies Larvae aquatic adult riparian
http//dnr.state.il.us/orep/ecowatch/RIVER/bugs/pa
ge1.htm
Whiligigg beetles Adults and larvae aquatic
http//academic.emporia.edu/aberjame/wetland/wildl
ife/wild24.jpg
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Heteroptera true bugs
Gerridae water striders
Aquatic larvae and adult Predators
http//www.inhs.uiuc.edu/sjtaylor/gerromorph/stri
ders.html
Notonectidae backswimmers Sucking
predators Creepy!!
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Belostomatidae giant waterbugs
Voracious predators Adults can fly In some spp
males carry eggs on back
http//creatures.ifas.ufl.edu/misc/bugs/belostomat
id01.htm
http//www.agls.uidaho.edu/ento/SixleggedWonders/i
nsects_of_idaho/hemiptera.htm
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Invertebrate Physiological Ecology (environmental
challenges)
Respiration Osmoregulation Thermoregulation
Current and buoyancy
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O2 is abundant in air much more scarce in water
take in atmospheric O2
take O2 from water
large surface area structures for diffusion
gill
gulp air at surface snorkel tap into
plants portable air source beetles
Heteroptera
many variations on gills must move water over
them
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Snorkels
http//www.bugsurvey.nsw.gov.au/html/popups/lge_wa
-sc_col.html
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Insect SCUBA
General insect respiratory systems is air-filled
channels called tracheaevery good for
terrestrial existence When diving beetle
(Dystsicus) is at surface it traps a bubble
under wings. The openings of the tracheae
(spiracles) are under the wings putting them in
direct contact with bubble O2 diffuses from
bubble into the tracheae. O2 may diffuse from the
water into the bubble so it acts like an
alveolus in a lung When the PO2 in the bubble
drops below some threshold the beetle returns to
the surface
http//www.eman-rese.ca/eman/reports/newsletters/m
onitor/vol_2_num_2/page07.html
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Gills highly vascularized respiratory structures
ex. mayfly larvae Water movement is important
tube aeration pushups Temperature (O2
saturation) is important
http//www.sigmaaldrich.com/Brands/Fluka__Riedel_H
ome/Analytical/Microscopy/Award_for_Microphotograp
hy/picture_gallery.html
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Osmoregulation
Terrestrial origin -Insects -Mites -Pulmonate
snails
Marine origin -Most others
Freshwater invertebrate fauna
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Ions salt
freshwater
marine
water
NaCl
NaCl
Active processes that require energy
NaCl
NaCl
ions
simple organisms are isotonic w/ sea water
more complex organisms have mechanism to
eliminate salt (e.g. concentrated urine)
live in hypotonic solution (tissue
hypertonic) need to take in ions and get rid of
water dilute urine
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Brackish environment appears to be the toughest
Number of species
0
30
20
10
After Fig 1.2 Pennak
Salinity (o/oo)
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Energy resources
Autotrophs Use light or a chemical energy source
to fix carbon. plants some
bacteria algae Heterotrophs Ingest carbon that
has been fixed by another organism. animals fung
i some bacteria some protists Mixotrophs Can
do both
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Invertebrate Heterotrophs Ingest carbon that
has been fixed by another organism
-Plants algae -Animals -Microbes -Detritus
Can be hard to say exactly what a particular
invert does for a living
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Things zoobenthos can eat location and quality
-Floating plankton phyto zoo seston stream
drift animal or detritus -On a surface (moving
or still water) plant low quality algae on
sediment rock plant animal probably
hiding detritus very low quality but doesnt
hide associated microbes good food
Balance of algae-animal-microbe-detritus affects
CNP ratio. In general high N P good food.
(ecological stoichiometry)
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Many bivalves live on bottom but feed on
plankton
http//www.md.mcnet.pl/relacje/img/Hancza/Dreissen
a20polymorpha203.htm
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Relatively few benthic inverts eat live
macrophytes. Why
Duarte C.M. 1992. Nutrient concentration of
aquatic plants pattern across species. Limnol
Oceonog 37882-889
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So why are the invertebrates in the littoral zone
if they dont eat the plants
pelagia
high benthos density diversity
low benthos density diversity
See 24.5
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Bottom feeding modes shredders- large particles
leaching
DOM
microbes
CPOM
shredders
feces fragments
Leaves etc become better food as they are
conditioned
FPOM
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Bottom feeding modes collectors - FPOM
DOM
feces fragments
FPOM
gatherers
filterers
feces
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Insects strongly affect fpom export
Insecticide treatment
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Bottom feeding modes Scrapers
DOM
Periphyton (algae microbes)
http//www.applesnail.net/content/snails_various.p
hp
feces
FPOM
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Bottom feeding modes Gardeners
-Benthic grazers also selective some caddisfly
and chironomid larvae actually remove but dont
consume unpalatable blue-greens from their
feeding areas -Otherwise grazing may favor
non-palatable species
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Theoretical effect of grazers on benthic algae
high
production
periphyton
biomass
low
Grazer density-grazing pressure
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Invertebrate Predators
Encounter
Most use mechanical or chemical means of
detection (a few use vision like fish)
Attack strategies
engulfers ingest all or most of prey in chunks
or whole most invertebrates prey usually
smaller than predator pierces inject digestive
enzymes and ingest prey in liquid form
backswimmers some beetles leeches prey can be
larger than predator
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Invertebrate predators are not much bigger than
their prey (compared fish)
probability of encounter is greater for bigger
prey
But
larger prey are harder to subdue and handle
So
Invertebrates may preferentially consume
intermediate sized prey
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Profundal zone benthos
--Many burrowing animals- sediment is
soft --Most can tolerate low O2 some w/
hemoglobin --Rely on detritus rain from
pelagic zone no primary production
http//zoology.okstate.edu/zoo_affl/ewqrl/services
3.htm
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Take home points
--Zoobenthos are a very diverse group and we tend
to study mainly the larger species. --Richness
and abundance highest in litoral zones
associated with macrophytes or other structures
--Zoobenthos have more ways to make a living
than zooplankton --Have adaptations to deal with
life in freshwater --Many different feeding
modes --Often important energy source to fish
(read Chapt 25.5 25.7)