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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
                                                Rotifers
   ~1500 species, size between 0.04 and 2.5 mm
   Generation time is a few days (temperature dependent)
         Can tolerate lower Water Residence Time than larger        Corona
          zooplankton
         Populations respond quickly to an increase in food resources
   Most are filter-feeders
         Use corona to create feeding current
   A few are predaceous (Asplanchna)
   Prey species may exhibit cyclomorphorosis


                                                                                       www.tolweb.org/tree/ToLimages/cava042p.jpg




          Asplanchna




www.microscopy-uk.org.uk/mag/artfeb02/fresh/freshimg/rotifers.jpg   cyclot.hp.infoseek.co.jp/wamusi/mituude1.jpg
                  Annelida: Oligochaeta
Bilaterally symmetrical

Segmented coelomates, each segment
w/ chaetae (little hairs/bristles)
                                           http://www.inhs.uiuc.edu/~sjt
                                           aylor/cave/oligochaeta.html


Hermaphroditic; sexual and asexual reproduction.
Usually paratomy (budding), also create cocoons filled
with embryos.

Wide spread, many habitats and trophic levels

Some spp used as pollution indicators- very tolerant

Bioturbators
                   Annelida: Hirudinea (leaches)
Dorsoventrally flattened &
segmented

Mouth surrounded by oral
sucker, parasites, scavengers
and predators

Only 2 common U.S. genera
that attack humans; sufficient
blood taken so that leach may
be 5 times original mass
                                  http://www.nanfa.org/akiweb/658.JPG



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/science/07leec.html
Famous invertebrates from Hollywood!
Arachnida: Hydrachnidia,
water mites

Look like tiny spiders, 6 legs

Most carnivorous or parasitic

Separate males and females
                                  http://images.google.com/imgres?imgurl=http://test.dnr.nsw.gov.au/care/

Can be very abundant in weedy     wetlands/facts/paa/invertebrates/images/water_mite_eylais.jpg&imgrefurl
                                  =http://test.dnr.nsw.gov.au/care/wetlands/facts/paa/invertebrates/watermi
                                  tes_aquaticspiders.html&h=338&w=400&sz=20&hl=en&start=14&sig2=eK

areas, usually found in shallow   Oanf2HjZpwetS9dOHqEA&tbnid=Mqsx3hWcSPtdEM:&tbnh=105&tbnw=12
                                  4&ei=OQEiR5adKaeceMq70KIC&prev=/images%3Fq%3Dwater%2Bmite%2
                                  6gbv%3D2%26svnum%3D10%26hl%3Den

waters

Beautiful colors (fade w/
preservative)

Hard to identify
                 Phylum Mollusca
                  (Life in a shell)

>100,000 spp.

Gastropods-snails & slugs

Bivalves- clams/mussels

Cephalopoda (squids, octapus, cuttlefish,
nautilus- marine)

Higher taxonomy messy
      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)
            gill (ctenidium)
            operculum

      150 pulmonates (derived from terrestrial)
           lung=modified mantel cavity
Valvata bicarinata




       Campeloma decisum




                                  Physella/Physa spp.


http://members.aol.com/mkohl1/FWshells.html =picture source
Consider a snail & leech of about same tissue mass.

What is the primary physical diff between them?

How does this diff affect their predators & where they live.

What affects their habitat choice more- trophic level or
potential predators?
                                  Bivalves
                NA bivalve fauna most diverse in word
superfamilies


                Unionoidea ~278 spp

                Corbiculacea 36 native and 4 introduced

                Dreissenoidea 2 spp (zebra and quagga mussels)
                                 (more later)




                         Mucket
                      Crustaceans
Specious, abundant and ecologically important

     >35,000 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
                      Branchiopods
 •     Most are filter feeders
         – feeding appendages act as
           electrostatic filters
         – Feed on phytoplankton, bacteria,
           protozoa
 •     Often the dominant herbivores in
       lake systems (before zebra
       mussels)
 •     Generation time is a few weeks
 •     Some are predators on other
       cladocerans and rotifers
       (Leptodora, Bythotrephes)                                   Bosmina
                                                                                                  webs.lander.edu/rsfox/rsfoximages3/clad99L_x550_x_643x.gif




                     Leptodora



                                             www.cof.orst.edu/project/plankton/bos.jpg



/www.internal.eawag.ch/~steiner/Zoo/Bilder




                                                                                         www2.biologie.uni-halle.de/zool/dev_biol/lect/pk_lim/limno/Daphnia.jpg
 Bythotrephes
                                                                     Male Daphnia




                                                          First
                                                          antennae




•   Branchiopods are usually parthenogenetic
     –   Produce eggs (clones) after each molt (~3-30
                                                                     Ephippium with 2
         eggs)                                                       resting eggs
•   Sexual reproduction can be triggered by
     –   Low food condition
     –   Decreasing photoperiod
     –   Overcrowding

•   Resting eggs are contained in an Ephippium
     –   Can be dried, transported on legs of waterfowl
     –   Eggs from Ephippia buried in sediments can
         survive decades
                                                Copepods
    Three major groups: Cyclopoida, Calanoida, (pelagic) and Harpactocoida
     (benthic)
           Always sexual reproduction, near equal numbers of
            males and females
    Cyclopoids
           Life Cycle
               •   Shorter generation time (1-2 months)
               •   Eggs hatch as nauplius larvae
               •   Several juvenile molts (copepodids) before becoming adults
               •   Juvenile stage may enter diapause in fall and re-activate in the spring
                                     Adult male                Adult female      Female with egg sacs




    http://www.emporia.edu/biosci/
    invert/lab6/copnaup1.jpg

                                        centexnaturalist.com
                                Copepods
   Calanoids
        Life Cycle
           •   Longer generation time (6 months or more)
           •   Eggs hatch as nauplius larvae
           •   Several juvenile molts (copepodids) before becoming adults
           •   No diapause


                                                       Adult female            Adult male




                                                          www.glerl.noaa.gov
www.sahfos.ac.u             www5.pbrc.hawaii.edu
                   Avoidance of Predation
    Cyclomorphosis
        Daphnia and others may grow long helmets and tail spines
         (inducible defenses) to help avoid invertebrate predators




                                                              www.unb.ca

                          www.esf.edu/efb/schulz/Art.html
www.nature.com
                              Cyclomorphosis


   Why not have long spines and helmets all the time?
       Energetically expensive, lowers reproductive rate
       Interferes with feeding in some cases (Bosmina)




          www.ecostudies.org/images          www.fbl.ku.dk
                     Avoidance of Predation
   Escape Tactics
        Calanoid copepod “jump” reaction
            • Flex 1st antennae to achieve burst of speed, acceleration up to 30G
              and 100 body lengths/second
        “Dead Man” response
            • Some small cladocerans (Bosmina, Diaphanosoma) may avoid
              detection by invertebrate predators by stopping all activity and
              allowing themselves to sink slowly

                                                                                       Bosmina

                                                                www.microscopy-uk.org.uk



                                                                                       Diaphanosoma

www.glerl.noaa.gov

                                    Epischura                  www.lbm.go.jp/emuseum
                Avoidance of Fish Predation
   Diel (Daily) Vertical Migration
    (DVM)
       Most zooplanktivorous fish are visual
        predators that feed during the day.
       Larger zooplankton species typically
        migrate downward during the day to
        avoid being seen by fish
       Migrate upward at night to feed on      www.wellesley.edu

        algae near the surface, more
        dispersed at night
                        Avoidance of Fish Predation
     Try to be as transparent as possible
            Especially true for large invertebrate predators (Chaoborus,
             Leptodora) and slow-moving species (Daphnia, Bosmina, etc)

                          Leptodora




                                                  Chaoborus
                                                  “Phantom midge”

www.lbm.go.jp/emuseum
                          www.internal.eawag.ch




                                                        www.microscopy-uk.org.uk
Order Anostraca; fairy shrimp
temporary pools or very saline
habitats (e.g. brine shrimp:
Artemia salina)


swim on backs by beating
appendages; also serves to
                                   http://www.cdpr.ca.gov/docs/es/esgifs/fairy.gif
obtain food

either sexual or parthanogenic
eggs; make resting eggs that
can hatch out when put in water,
“sea monkeys”
How do the defense strategies of pelagic and benthic
animals differ?

Why?
Order Isopoda (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 preadult
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/Asellus_aquaticus.jpg
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                   http://www.nativefish.org/Gallery
                                                 /other/Gammarus-sp..htm
marsupium, young are released at the
females next molt
               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."
5 aquatic orders, almost all spp have aquatic larvae

     Ephemeroptera         Trichoptera
     Odonata               Megaloptera
     Plecoptera



5 partially aquatic orders, most species are terrestrial,
but some spp have aquatic life stages

      Heteroptera           Lepidoptera
      Coleoptera            Neuroptera
      Diptera
  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.php?idnum=8
Adults do not feed

Females oviposit usually at water surface

Burrowing mayflies (Hexagenia) important species in
western Lake Erie




                                    Mating
                                    swarm near
                                    Sandusky
                                    River




    Collecting females at Windsor          http://www.heidelberg.edu/depts/wtr/krieger.html
                         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.naturewatch.ca/eman/rep
                            orts/publications/99_montane/odona
                            ta/odonatafig06.html
http://www.entomology.umn.edu/museum/links/coursefiles/Odonate%20characters.html
                Plecoptera: stoneflies

~614 spp

Most common in fast, cold streams

Larvae predators

2 long tail filaments

Long antennae

Larvae crawl rather than swim
                                http://www.weeksbay.org/newslet
Adults live days to weeks       ter/Sum_2003/Pg8_1.htm
Trichoptera: Caddisflies




http://www.wildscape.com/earrings.asp
  ~1400 spp

  Lotic & lentic

  Adults terrestrial and easily identified, but
  many larvae unknown

  Some build silk nets to catch prey
  Some free living predators                                            http://www.nativefish.org/G
                                                                        allery/other/Caddisfly.htm
  Some build cases

                                                         Can be dominant in streams

                                                         Many fish feed on larvae

                                                         Can have large hatches

http://www.epa.gov/bioindicators/html/caddisflies.html
         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_invertebrates.html
5 aquatic orders, almost all spp have aquatic larvae

     Ephemeroptera         Trichoptera
     Odonata               Megaloptera
     Plecoptera



5 partially aquatic orders, most species are terrestrial,
but some spp have aquatic life stages

      Diptera               Lepidoptera
      Coleoptera            Neuroptera
      Heteroptera
                 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)
          Chironomidae: midge larvae (+ 2000 spp)


Very important fish
food

Wide range of
ecology
                                      http://www.biol.wwu.edu/4
                                      07/407/Crustaceans.html
Tipulidae: cranefly larvae

                                                          http://alpaca.cs.umb.edu/gal
                                                          lery/Aquatic-
                                                          Invertebrates/tipulidD_thm


                                             Chaoboridae: phantom
                                             midge larvae

                                             Pelagic predators



            http://www.iii.to.cnr.it/limno
            l/bentos/cauborus.JPG
                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/acad
                                           emic/departments/zooent
                                           o/Martin/elmidae.html
“water pennies”

Larvae aquatic, adult riparian


                                              http://dnr.state.il.us/or
                                              ep/ecowatch/RIVER/
                                              bugs/page1.htm




                                 Whiligigg beetles

                                 Adults and larvae aquatic
  http://academic.emporia.edu
  /aberjame/wetland/wildlife/w
  ild24.jpg
              Heteroptera: true bugs

   Gerridae: water striders

Aquatic larvae and adult
                                                  http://www.inhs.uiuc.edu/~
Predators                                         sjtaylor/gerromorph/strider
                                                  s.html




                              Notonectidae: backswimmers

                              Sucking predators

                              Creepy!!
     Belostomatidae: giant waterbugs
                                               Voracious predators

                                               Adults can fly

                                                In some spp males
                                               carry eggs on back




http://creatures.ifas.ufl.edu/misc/bugs/belo
               stomatid01.htm
                                                      http://www.agls.uidaho.edu/ento/Si
                                                      xleggedWonders/insects_of_idaho/
                                                      hemiptera.htm
 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 doesn’t hide,
            associated microbes = good food

Balance of algae-animal-microbe-detritus affects C:N:P
ratio. In general high N & P = good food.
Relatively few benthic inverts eat live macrophytes.
                        Why?
     Duarte, C.M. 1992. Nutrient concentration of aquatic plants: pattern
     across species. Limnol & Oceonog 37:882-889
So why are the invertebrates in the littoral zone if they don’t eat the plants?




                                                      pelagia

              high benthos
            density & diversity




                                                             low benthos
                                                          density & diversity

See 24.5
              Take home points

--Benthos are much more diverse (and interesting ) than
zooplankton
--Humans tend to study larger size classes
--Many different feeding modes
--Richness and abundance highest in litoral zones,
associated with macrophytes or other structures
--Often important energy source to fish

				
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