inverts pt 2

arthopoda

• arthropods

• subphylum chelicerata (water mites & spiders)

• subphylum pancrustacea (crustaceans & hexapods)

types of metamorphosis

• ametabolous

• hemimetabolous

• holometabolous

simple metamorphosis

ametabolous

• no change in organism between stages, except for size

incomplete metamorphosis

hemimetabolous

• immature insects look similar to adults. Nymphs don’t have wings and adults have wings

complete metamorphosis

holometabolous

• immature look nothing like adults

hexapods

• 6 legged

• three body segments (head, thorax & abdomen)

hexapod orders

• collembola

• ephemeroptera

• odonata

• plecoptera

• hemiptera

• coleoptera

• neuroptera & megaloptera

• trichoptera

• lepidoptera

• diptera

collembola

• glue-peg; springtail

• minute hexapods

• with or without jumping structure (furcula)

• up to 8 ommatidia

• short antennae

• mostly terrestrial, few aquatic species

• ametabolous

ephemeroptera

• bioindicators

  • EPT taxa

• short-lived wings; mayflies

• wings held above body at rest

• 2 or 3 cerci

• leafy gills on abdomen

• only order where they molt again after having functional wings

• hemimetabolous

• found in lentic or lotic water

• larvae feed on a variety of food

• adults do not feed, they reproduce and die

odonata

• tooth; dragonflies & damselflies

• bioindicators

• compound eyes

• 3 ocelli

• antennae short & bristle-like

• suborder: zygoptera (damselflies)

• suborder: anisoptera (dragonflies)

• carnivores/ predators as larvae & adults

• adult stages are easy to ID, larvae pretty much all look the same

• hemimetabolous

plecoptera

• folded-wing; stoneflies

• EPT taxa

  • associated with clean, cool running water

• somewhat flattened, soft-bodied

• poor fliers

• aquatic larvae

• hemimetabolous

• many emerge during winter months

heimptera

• half-wings; true bugs

• large & diverse group

• wings are part membranous, part leathery

• hemimetabolous

coleoptera

• sheath-wings; beetles

• largest order of insects (+28,00 NA species)

• forewings modified into wing covers (elytra)

  • hard & leathery, usually meet in a straight line on the back

• holometabolous

neuroptera & megaloptera

• alderflies, dobsonflies, fishflies, hellgrammites

• originally grouped together

• larvae are mostly predaceous

• adults vary

• holometabolous

neuroptera

• nerve-wings; lacewings, antlions & owlflies

• soft-bodied

• four membranous wings

• many cross veins & extra branches

• some larvae are aquatic

• adults are weak fliers

• holometabolous

megaloptera

• alderflies, dobsonflies and fishflies

• bioindicators

• hellgrammites (dobsonfly larvae) are the largest stream insects, well adapted for hunting in riffles

• life cycle:

  • females lay their eggs on trees that overhang streams

  • young falls into the water and lives in the stream for three years

  • emerges and pupates on land and turns into the adult

• adults are usually nocturnal

trichoptera

• hair-wings; caddisflies

• EPT

• somewhat mothlike appearance

• 4 membranous wings that are hairy

• larvae: collectors, some predators

  • build cases and collect food, have hook-like appendages on abdomen

• holometabolous

lepidoptera

• scale-wings; butterflies & moths

• scales on wings

• large compound eyes

• holometabolous

diptera

• two-wings; true flies

• forewings present, hind wings absent

• hind wings modified into halteres (maintains equilibrium while flying)

• holometabolous

• not good bioindicators

crustaceans

• paraphyletic group

• cladocerans and copepods are key primary consumers in many lakes & ponds

crustacean orders

• ostracoda

• copepoda

• branchipoda

• decapoda

• isopoda

• amphipoda

ostracoda

• seed shrimp

• shells are important in paleolimnology

• occur in most habitats, even hypersaline and hot springs

copepoda

• important zooplankton in both freshwater and marine systems

• larval stage- nauplius

• eggs can be resistant to drying

branchiopoda

• cladocera (water fleas), fairy, tadpole, brine, and clam shrimp

• primarily in lotic environments

• cladocerans can produce eggs encased in an ephippium than can remain dormant for centuries

decapoda

• crayfish, crabs, shrimp

• mostly marine or estuarine, but many freshwater species

isopoda

• terrestrial pill bugs

• many marine species, and few freshwater species

• generally detritivores

amphipoda

• scuds and sideswimmers

• similar in size to isopods, but laterally flattened

• omnivorous and scavengers

why are macroinverts good bio-indicators?

• taxa are differentially sensitive to pollution

• they are not very mobile and thus cannot escape short- or long-term pollution events

• they are relatively long lived

• they are present in most streams, even those that lack fish

• relatively easy to catch, view, and identify