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 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 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 –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

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 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 Courtesy of: UM Museum Animal Diversity Web

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 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 Courtesy of: UM Museum Animal Diversity Web

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: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 cephalothorax –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.Tarsus/tarsal claw 2.Cercus 3.Pronotum 4.Mesonotum 5.Metanotum

Exopterygotes 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

Endopterygotes 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

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