Transcript Document

Freshwater Macroinvertebrate
Diversity
ENVIRON 311 / EEB 320
Winter 2007
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
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
Phylum Annelida
Class 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
Phylum Annelida
Class 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
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
Credit: Josee Soucie, Biodidac
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)
Phylum Mollusca
Class Gastropoda, Family Ancylidae
Web
• Limpets
• Habitat: Well-aerated hardwater streams; other
waters with emergent rocks or vegetation
• Notes:
Courtesy of: UM Museum Animal Diversity
– Univalve shell does not spiral
– Feeds mainly on algae
Phylum Mollusca
Class Gastropoda, Family Lymnaeidae
• Pond snails
• Habitat: varies;
common in lakes and
ponds
• Notes:
– Pointy, spiraled shell
opens to the right
(dextral)
– Feeds on periphyton
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
Courtesy of: UM Museum Animal Diversity Web
– They turned out to be the
species on the top left but
their development had been
altered by a changed
environment
Phylum Mollusca
Class Gastropoda, Family Physidae
• Pouch snails
• Habitat: varies;
common in lakes and
ponds
• Notes:
– Pointed, spiraled shell
opens to left (sinistral)
– Feeds on periphyton
Phylum Mollusca
Class 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
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)
Phylum Mollusca
Class Bivalvia, Family Dreissenidae
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
Phylum Mollusca
Class 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
Phylum Mollusca
Class 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
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
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
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)
Phylum Arthropoda
Superclass Crustacea
• Characteristics of
crustaceans
– Two pairs of antennae
– Head and thorax usually
fused into cephalothorax
– Three pairs of mouthparts
– Usually > three pairs of legs
• Habitat:
– Primarily aquatic and mostly
marine
Phylum Arthropoda
Superclass Crustacea, Order Ostracoda
• Seed shrimp
• Habitat: shallow
wetlands to sea floor
depths
• Notes:
– Feed on detritus,
plankton
– Body protected by
bivalve carapace
Phylum Arthropoda
Superclass 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
Phylum Arthropoda
Superclass Crustacea, Order Isopoda
• Sowbugs
• Habitat: mostly marine but a
few freshwater
• Notes
– Dorsoventrally compressed
– Seven pairs of legs
– Tend to prefer vegetated
lentic or sluggish lotic
habitats
– Consume detritus
– Related to terrestrial
pillbugs
Phylum Arthropoda
Superclass 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 year…and may
vary greatly in number from
year to year
– Filter feeders
Phylum Arthropoda
Superclass 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
Phylum Arthropoda
Superclass 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 (<2 mm)
Phylum Arthropoda
Superclass 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
Basic Insect Anatomy
1.
2.
3.
4.
5.
Tarsus/tarsal claw
Cercus
Pronotum
Mesonotum
Metanotum
Class Insecta
Exopterygotes
• 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
Class Insecta
Order Ephemeroptera
• Mayflies
• Habitat: mostly cool lotic
waters; some also live in
lentic waters
• Notes:
– Very important source of
food for many fish
– 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
Class Insecta
Order 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
Class Insecta
Order 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
Class Insecta
Order 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
Dragonfly Feeding
Class Insecta
Order 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
Class Insecta
Order 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
Class Insecta
Order Hemiptera
• Unique features:
– Males in Family Belostomatidae carry eggs on back until
they hatch
– Members of Family Notonectidae swim on their backs—
hence their common name: backswimmers
Class Insecta
Endopterygotes
• 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)
Class Insecta
Order 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
Class Insecta
Order Megaloptera
• Video of a vicious larval
dobsonfly
• Note display of large
mandibles
• Also, lateral filaments
not used in locomotion
Class Insecta
Order 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
Class Insecta
Order 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
Class Insecta
Order Trichoptera
• Case building
caddisflies spend a lot
of time in their cases
EPT
• Ephemeroptera, Plecoptera, Trichoptera
– Index for streams: the count of EPT taxa (often at
the genus level)
• AKA: EPT Richness
E, P, T = 3 orders of aquatic insects that tend to be
most abundant in relatively unpolluted waters, so more
is better
Usually do % EPT per total
Class Insecta
Order 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
Class Insecta
Order 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
Dipteran Photos
The End