Aquatic Macroinvertebrate Resources

Phylum Porifera (sponges)

        This sponge gets its green color from symbiotic algae (zoochlorellae)
        Learn more about sponges >>

Phylum Platyhelminthes
    Class Tubellaria (flatworms)

source of photo: >>

Phylum Rotifera (rotifers)

Phylum Annelida

    Class Oligochaeta* (bristle worms)

            Interesting stuff about Tubifex worms >>


    Class Hirundinea* (leeches)


Phylum Mollusca

    Class Gastropoda* (snails)


    Class Pelecypoda* (clams and mussels)

Cyclonaias tuberculata, INHS 4078. Source of photo:
List with lots of mollusk links >>

Phylum Arthropoda
- exoskeleton, which must be molted for body to grow
- body segments (head, thorax, abdomen)
- paired jointed appendages

Superclass Crustacea
    - head and thorax "fused" into a structure called a cephalothorax
    - two pairs of antennae
    - breath with gills

    Order Ostacoda - seed or clam shrimp
    - minute crustaceans with large head, its trunk reduced in size
    - bivalve calcareous carapace
    - almost all are free-living, both marine and freshwater forms

    Order Amphipoda* - scuds, side-swimmers

    - bilaterally compressed (narrow), look like tiny shrimp
    - head and first segment of thorax fused into a cephalothorax
    - seven free thoracic segments, with 2 pair of pleopods which beat to move water over the gills
    - small tail plate (telson)
    - active at night
    - benthic, primarily scavengers of fine detritus, or shredders
    - can be common, some species adapted adapted to subterranean environments
    - two common families in Michigan - Gammaridae, Hyalellidae

    Order Isopoda* - aquatic sowbugs, isopods

    - dorsoventrally compressed (flat)
    - head fused with first and second segment of thorax into a cephalothorax
    - seven other thoracic segments each with a pair of legs (pereopods)
    - four abdominal segments fused to tail plate (telson)
    - six pairs of abdominal legs (pleopods, and 6th uropods)
    - live just about everywhere and often where other things cannot
    - scavengers, hide in accumulated vegetative matter in rivers and lakes
    - one common family in Michigan - Asellidae

    Order Mysideacea - opossum shrimp
    - shrimp-like, with large carapace, and stalked eyes
    - live in deep lakes, often have dramatic cycles of diurnal vertical migration

   Order Copepoda* - copepods
    - mostly marine, but significant numbers of species that are freshwater
    - immature copepods called "nauplius"
    - cylindrical shape, narrow abdomen, often conspicuous as females often are seen carrying egg sacs
    - laterally compressed, with a single folded carapace
    - very small (usually <0.5-2.0mm), noticeably segmented bogy with numerous appendages on head
      and thorax, and setose caudal rami on posterior end of abdomen
    - filter feeders, feed on organic detritus and other smaller animals; some species parasitic on fish
    - of the free-swimming species, three important suborders:
            - Calanoida, planktonic species with long antennae, filter feeders - dominant freshwater group
            - Cyclopoida, littoral species with short antennae
            - Harpacticoida, littoral species with very short antennae (largely a marine group)

    Order Cladocera* - water fleas

    - laterally compressed (narrow), with a single folded carapace open at the bottom, doesn't cover head
    - 5-6 pairs of legs
    - antennae (biramous Y-shaped) chief locomotive organ
    - primary consumers, visual predators, majority feed on algae and cyanobacteria, use their legs to filter feed
    - often an important link in aquatic food chains, widely preyed upon by insects and fish
    - soon responds to increases in productivity with turnover events
    - reproduction parthenogenetic, males produced in spring in response to crowding
    - populations with diel vertical migration, staying at depths during the day, rising to near the surface at night
      to feed
    - found in most still water, planktonic in lakes, in weedy lake margins, a few in bogs, along lake bottoms
      or in the mud

   Order Anostraca* - fairy shrimp

    - elongated trunk
    - many paired appendages, swims on back
    - stalked, compound eyes
    - carapace absent

   Order Decapoda* - crayfish and freshwater shrimp
Cambaridae: Crayfish
    - diverse marine and freshwater order, some individuals attain the largest size of any of our crustaceans
    - most freshwater decapods inhabit shallow lentic and lotic waters, also some inhabit terrestrial burrows
      that lead to groundwater, and some are subterranean (caves)
    - head and thorax combined into a very prominent cephalothorax, which often has an anterior, elongated
      projection (rostrum)
    - feathery gills in a gill chamber underneath the legs
    - females carry eggs on pleopods
    - several types of crayfish borrow into the ground, making chimneys (response to drought)
    - largely nocturnal, omnivorous feeding

            Family - Cambaridae - crayfish
            - body cylindrical
            - appendages modified
                    - 2 pairs of antennae
                    - 5 pair of legs used for walking and food handling (1st 3 are chelate, 1st a large forcept)
                    - 5 pair of pleopods on abdomen

            Family - Palaemonidae - freshwater shrimp
            - body laterally compressed (narrow)
            - first 2 paris of legs are chelate, the rest are adapted for swimming
            - generally found in macrophyte-rich littoral zones of lakes or similarly macrophyte-chocked sections
              of rivers and streams

Phylum Arthropoda - Superclass Arachnida

    Order Acari* - watermites
    - larvae are 6-legged, adults are 8-legged
    - complicated life cycle - egg, sometimes parasitic larvae, sometimes parasitic deuteronymph which
      disperses, and adult
    - over 5,000 species, probably very conservative number; over 1,500 described in North America

Phylum Arthropoda
Superclass* Hexapoda
see above link to view images