Freshwater Macroinvertebrate Diversity ENVIRON 311 / EEB 320 Winter 2007.

Freshwater Macroinvertebrate Freshwater Macroinvertebrate DiversityDiversity

ENVIRON 311 / EEB 320ENVIRON 311 / EEB 320

Winter 2007Winter 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 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

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

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 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

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

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


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

Phylum MolluscaClass Gastropoda, Family Planorbidae

• 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 MolluscaClass 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 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

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


Phylum Arthropoda

• 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 Major advantages of being an insect: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 ArthropodaSuperclass Crustacea

• Characteristics of crustaceans– Two pairs of antennae

– Head and thorax usually fused into cephalothoraxcephalothorax

– Three pairs of mouthparts

– Usually > three pairs of legs

• Habitat: – Primarily aquatic and mostly

marine

Phylum ArthropodaSuperclass Crustacea, Order Ostracoda

• Seed shrimp• Habitat: shallow

wetlands to sea floor depths

• Notes:– Feed on detritus,

plankton– Body protected by

bivalve carapace

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

Phylum ArthropodaSuperclass 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 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 year…and may vary greatly in number from year to year

– Filter feeders

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

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 (<2 mm)

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

Basic Insect AnatomyBasic Insect Anatomy

1. Tarsus/tarsal claw

2. Cercus

3. Pronotum

4. Mesonotum

5. Metanotum

Class InsectaExopterygotesExopterygotes

• 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 InsectaOrder 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


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

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

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

Dragonfly Feeding

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

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

Class InsectaOrder 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 InsectaEndopterygotesEndopterygotes

• 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 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

Class InsectaOrder Megaloptera

• Video of a vicious larval dobsonfly

• Note display of large mandibles

• Also, lateral filaments not used in locomotion

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


• 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


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

EPTEPT

• 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 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

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

Dipteran Photos

The End

Freshwater Macroinvertebrate Diversity ENVIRON 311 / EEB 320 Winter 2007.

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Transcript of Freshwater Macroinvertebrate Diversity ENVIRON 311 / EEB 320 Winter 2007.