Freshwater Macroinvertebrate Diversity

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Freshwater Macroinvertebrate Diversity

• ENVIRON 311 / EEB 320
• Winter 2006

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Phylum Platyhelminthes Class Turbellaria

• Flatworms
• Habitat widespread in marine and freshwater
• Notes
• Class Turbellaria free-living (Some others are
  parasites)
• Dorsoventrally flattened no body cavity
• Not segmented
• Some marine species are brilliantly colored
• One of first animals to display bilateral
  symmetry

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Phylum Platyhelminthes Class Turbellaria

• Anatomy/Physiology
• Displays primitive cephalization (development of
  a head)
• Feeding is through ventral mouth
• No digestive outlet wastes diffuse across body
  membranes
• Can reproduce asexually through fragmentation

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Phylum AnnelidaClass Oligochaeta

• Bristle worms
• Habitat Widespread in marine and fresh waters
• In fresh water, commonly prefers fine sediments
  with plentiful organic carbon
• Notes
• Cylindrical, multisegmented body
• Setae present
• Anterior mouth for eating and anus for excretion
• Abundance of certain species may be indicator of
  pollution

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Phylum AnnelidaClass Hirudinea

• Leeches
• Habitat Vegetated spots in lakes and sluggish
  parts of rivers
• Notes
• Dorsoventrally flattened
• Multisegmented
• Parasite of vertebrates and predator of small
  invertebrates
• Three teeth in mouth allow it to cut into host
• Anticoagulants keep blood flowing
• After decent meal, may not need to feed for 100
  days

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Class Hirudinea

• Leech locomotion
• Use anterior and posterior suckers in sequence to
  anchor body while muscles selectively contract
• Needs hard substrate for locomotion cannot live
  in disturbed, silty habitats
• Reproduction
• Hermaphroditic with reciprocal cross-fertilization

Credit Josee Soucie, Biodidac
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Phylum Mollusca

• Molluscs (Mollusks)
• Class Gastropoda
• Snails
• Univalve shell covers soft, unsegmented body with
  foot and tentacles
• Highly mobile
• Subclass Prosobranchia has gills and operculum
• Subclass Pulmonata has lungs and no operculum
• Prefer hard waters (used to maintain calcareous
  shell)

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Phylum MolluscaClass Gastropoda, Family Ancylidae

• Limpets
• Habitat Well-aerated hardwater streams other
  waters with emergent rocks or vegetation
• Notes
• Univalve shell does not spiral
• Feeds mainly on algae

Courtesy of UM Museum Animal Diversity Web
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Phylum MolluscaClass Gastropoda, Family
Lymnaeidae

• Pond snails
• Habitat varies common in lakes and ponds
• Notes
• Pointy, spiraled shell opens to the right
  (dextral)
• Feeds on periphyton

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Ecophenotypes in Snails

• Snails at top left and right are different
  species of lymnaeids
• When placed together in the aquarium, the
  offspring (at bottom of photo) appeared to be
  intermediate
• They turned out to be the species on the top left
  but their development had been altered by a
  changed environment

Courtesy of UM Museum Animal Diversity Web
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Phylum MolluscaClass Gastropoda, Family Physidae

• Pouch snails
• Habitat varies common in lakes and ponds
• Notes
• Pointed, spiraled shell opens to left (sinistral)
• Feeds on periphyton

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Phylum MolluscaClass Gastropoda, Family
Planorbidae
Courtesy of UM Museum Animal Diversity Web

• Orb snails
• Habitat common in lakes and ponds
• Notes
• Shell spiraled but not pointed roughly in one
  plane
• Like most other freshwater gastropods, feeds
  largely on periphyton

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Phylum Mollusca

• Class Bivalvia
• Clams and Mussels
• Found in marine and fresh waters
• Bivalve shell encloses soft body with foot that
  can project for movement
• Mainly filter feeders
• Prefer hard waters to preserve calcareous shell
• Almost 1/3 of all freshwater mussels found in the
  US (most in SE)

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Phylum MolluscaClass Bivalvia, Dreissena
polymorpha

• Zebra mussel
• Introduced to Great Lakes in 1988 now occurs
  throughout most of Ohio/Mississippi River system
• Occurs on hard substrates
• Invasive species that competes with rare native
  mussels and may exclude other invertebrates
• May also increase bioaccumulation of harmful
  pollutants in smallmouth bass
• Via another introduced species the round goby

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Phylum MolluscaClass Bivalvia, Families
Corbiculidae and Sphaeriidae

• Asian and Fingernail Clams
• Habitat Found in wide variety of lentic and
  lotic sediments
• Corbiculids introduced from Asia
• Show fewer and more pronounced ridging on
  exterior of valves
• Sphaeriids native
• Show shallow ridging
• Gradually disappearing from many areas

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Phylum MolluscaClass Bivalvia, Family Unionidae

• Freshwater mussels
• Habitat clean streams, lakes
• Notes
• One of the most threatened animal groups in North
  America due to pollution, habitat loss,
  overharvesting and zebra mussel (which may seal
  valves shut)
• Many lotic species seriously affected by dams

Courtesy of UM Museum Animal Diversity Web
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Phylum Arthropoda
Courtesy of UM Museum Animal Diversity Web

• Extremely diverse group
• Includes the crustaceans, myriapods, arachnids
  and insects
• Wide variety of adaptations
• Have colonized freshwater, marine, and
  terrestrial habitats around the world
• Found everywhere from tar pits to the Antarctic
  ice sheets to ocean trenches

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Dominance of the Arthropods

• Arthropods make up an enormous proportion of all
  species of life
• The insects themselves make up more than half of
  all species diversity on the planet
• Major advantages of being an insect
• Flight
• Size (relative strength, general ease of
  diffusive respiration)
• Rapid reproductive rate

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Characteristics of Arthropods

• Possess hard exoskeleton
• In order to grow, must molt
• Segmented body, legs, mouthparts and antennae
• Reflects specialization and reduction of segments
  from earlier forms (e.g. segmented worms)
• Head, thorax and abdomen present (though
  sometimes fused)
• Eyes (usually)

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Phylum ArthropodaSuperclass Crustacea

• Characteristics of crustaceans
• Two pairs of antennae
• Head and thorax usually fused into cephalothorax
• Three pairs of mouthparts
• Usually gt three pairs of legs
• Habitat
• Primarily aquatic and mostly marine

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Phylum ArthropodaSuperclass Crustacea, Order
Ostracoda

• Seed shrimp
• Habitat shallow wetlands to sea floor depths
• Notes
• Feed on detritus, plankton
• Body protected by bivalve carapace

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Phylum ArthropodaSuperclass Crustacea, Order
Amphipoda

• Scuds, sideswimmers
• Habitat Widespread in marine and fresh waters
• Notes
• Laterally compressed body
• Seven pairs of walking appendages
• Feed mainly on detritus
• Abundant and important food source for many
  fishes where amphipods are in decline, some fish
  species will follow
• Prolific will often be found mating

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Phylum ArthropodaSuperclass Crustacea, Order
Isopoda

• Sowbugs
• Habitat mostly marine but a few fw
• Notes
• Dorsoventrally compressed
• Seven pairs of legs
• Tend to prefer vegetated lentic or sluggish lotic
  habitats
• Consume detritus
• Related to terrestrial pillbugs

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Phylum ArthropodaSuperclass Crustacea, Order
Anostraca

• Fairy shrimp
• Habitat Ephemeral and permanent wetlands/ponds
• Notes
• Lacks carapace
• Stalked eyes
• Uses many appendages to swim on its back
• Many populations only around for short periods of
  time each yearand may vary greatly in number
  from year to year
• Filter feeders

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Phylum ArthropodaSuperclass Crustacea, Order
Decapoda

• Crayfishes and shrimps
• Habitat Ubiquitous in fresh and marine waters
  some are quasi-terrestrial
• Notes
• Cylindrical body
• Three anterior leg pairs equipped with chelae
  (moveable fingers)
• When startled, raises claws or swims backward
  using telson
• Omnivorous eats everything from macrophytes to
  small fish

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Phylum ArthropodaSuperclass Hexapoda, Class
Parainsecta, Order Collembola

• Springtails
• Habitat surface film of fresh water
• Notes
• Possess six legs, like the insects, but do not
  develop wings
• Head, thorax and abdomen distinct
• Posterior jumping organ (furcula) present
• Mainly a terrestrial order
• Usually very small (lt2 mm)

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Phylum ArthropodaSuperclass Hexapoda, Class
Insecta

• Aquatic insects are ubiquitous in aquatic
  ecosystems, mostly in the larval stage
• Because the adults are able to fly, they have
  easily colonized almost all terrestrial and
  freshwater ecosystems
• Less successful in the oceans, where flight is
  not as advantageous

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• Basic Insect Anatomy
• Tarsus/tarsal claw
• Cercus
• Pronotum
• Mesonotum
• Metanotum

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Class InsectaExopterygotes

• Include those insects that possess wingpads in
  larval (nymphal) stage
• Larvae resemble adults (though sometimes
  loosely), have compound eyes and chitinous (hard)
  bodies
• Pass from egg to nymph to adult stage (no pupal
  stage)
• Aquatic members
• Ephemeroptera, Odonata, Plecoptera and Hemiptera

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Class InsectaOrder Ephemeroptera

• Mayflies
• Habitat mostly cool lotic waters some also live
  in lentic waters
• Notes
• Very important source of food for many fish (some
  time mayfly emergences)
• Usually fairly intolerant of pollution good
  indicator taxon
• Adults do not feed only mate and die
• Some nymphs are predators, most are grazers or
  filterers

Courtesy of UM Museum Animal Diversity Web
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Class InsectaOrder Ephemeroptera

• Many species can move their gills to ventilate
  when dissolved oxygen levels are low
• ID
• usually three terminal filaments
• One tarsal claw
• Gills may be present on sides of abdomen

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Class InsectaOrder Odonata, Suborder Anisoptera

• Dragonflies
• Habitat lentic and lotic
• Notes
• Obligate predator as both nymph and adult
• Nymphs characterized by large extensible labium
  (lower lip), wide body and tiny cerci on last
  abdominal segment
• Adults hold wings to sides, may be brightly
  colored

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Class InsectaOrder Odonata, Suborder Zygoptera

• Damselflies
• Habitat lentic and lotic
• Notes
• Obligate predator in all life stages
• Nymph characterized by head wider than body and
  three terminal lamellae (gills)
• Also has extensible labium
• Adult holds wings up over body may be highly
  colored

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Dragonfly Feeding
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Class InsectaOrder Plecoptera

• Stoneflies
• Habitat cool, fast streams
• Notes
• Generally sensitive to environmental
  perturbations good indicator taxon
• Nymphs may be shredders, grazers or predators
• Nymphs have two filamentous cerci and two tarsal
  claws
• Adult able to fold wings onto body, generally
  short-lived and dull-colored

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Class InsectaOrder Hemiptera

• True Bugs
• Habitat mainly lentic and sluggish lotic
• Notes
• Nymph and adult hard to tell apart
• Mostly predators use piercing mouthpart and
  raptorial forelegs to attack prey
• Some forms skate on water surface others swim
  below surface

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Class InsectaOrder Hemiptera

• Unique features
• Males in Family Belostomatidae carry eggs on back
  until they hatch
• Members of Family Notonectidae swim on their
  backshence their common name backswimmers

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Class InsectaEndopterygotes

• Include those insects that do not possess
  wingpads in larval stage
• Larvae have simple eyes, bear little resemblance
  to adults, and have generally softer bodies
• Pass from egg to larval to pupal to adult stage
• Aquatic members
• Megaloptera, Neuroptera (lacewings),
  Trichoptera, Lepidoptera (butterflies/moths),
  Coleoptera, Diptera, Hymenoptera (wasps)

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Class InsectaOrder Megaloptera

• Dobsonflies, Hellgrammites, Fishflies
• Habitat Mainly swift lotic
• Notes
• May grow quite large
• Larvae are predatory, characterized by large
  mandibles, lateral filaments
• Adult males grow large tusks, used in mating
  usually short-lived
• Relatively small group

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Class InsectaOrder Megaloptera

• Video of a vicious larval dobsonfly
• Note display of large mandibles
• Also, lateral filaments not used in locomotion

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Class InsectaOrder Trichoptera

• Caddisflies
• Habitat wide variety of lentic/lotic ecosystems
• Notes
• Some larval caddisflies build cases, others are
  free-living
• Note soft abdomen
• Wide range of feeding types, from predatory to
  filter feeding
• Characterized by two anal prolegs, in addition to
  thoracic legs
• Adults are dull, resemble moths

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Class InsectaOrder Trichoptera

• Wide variety of cases among species that build
  them
• May consist of mineral or organic materials
• Utilized mainly to allow ventilation sometimes
  for protection
• Many taxa can be identified by unique cases

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Class InsectaOrder Trichoptera

• Case building caddisflies spend a lot of time in
  their cases

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Class InsectaOrder Coleoptera

• Beetles
• Habitat wide variety of lentic and lotic
• Notes
• Larvae entirely aquatic
• Larvae are variable in form but usually elongate
  and often with unsegmented terminal filaments
• Adults often predacious or scavengers
• Adults characterized by very hard body and
  covered first pair of wings

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Class InsectaOrder Diptera

• True Flies
• Habitat extremely variable sometimes found in
  marine ecosystems
• Notes
• Very diverse family
• Larvae have no segmented legs and often reduced
  head may have one or more pairs of prolegs
• Larvae have variety of feeding habits
• Adults have only one pair of wings
• Adults may be parasitic or nectar feeding

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Dipteran Photos
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The End