Environmental Engineering Reference
In-Depth Information
6.3.1.1 Major Taxonomic Groups
All of the heterotrophic macroinvertebrates are included in the Animalia kingdom. This king-
dom includes the phylum Chordata, which includes mammals and birds that have a backbone.
Major macroinvertebrate phyla include the Arthropoda (e.g., insects and crustaceans), Mollusca
(e.g., snails, clams, and mussels), Annelida (e.g., worms and leeches), and Platyhelminthes (e.g.,
latwor ms).
6.3.1.1.1 Arthropods (Insects and Crustaceans)
Insects are typically the most numerous of the macroinvertebrates in unpolluted streams and rivers,
comprising 70%-90% of the macroinvertebrates, andincluding 13 taxonomic orders (Cushing and
Alan 2001), a few of the more common of which are illustrated in Figure 6.7.
Some of these insects, such as the mayly, caddis ly, and stone ly, are very sensitive to pollution
and, as such, are used as indicators of good watershed health, as will be discussed in Chapter 7.
Conversely, some ly larvae, such as the midge larvae, are most commonly found in highly pol-
luted waters. Also called bloodworms, they are reddish in color since they have hemoglobin in their
blood, which allows them to live in waters with low dissolved oxygen concentrations.
Some of the insects spend only part of their lives in streams and rivers. For example, true lies
(those with only one pair of wings) occur primarily in their larval stage in streams and rivers.
The ly's life cycle development involves undergoing complete metamorphosis (referred to as holo-
metabolous). It passes through four stages of development: egg, larvae, pupa, and adult; and the
larval stage does not resemble the adult stage. This development can take only a week for some
Order Ephemeroptera (may fly)
Order Diptera (true fly)
Order Odonata (dragon fly)
Order Coleoptera (beetle)
Order Megaloptera (hellgrammites)
rder Hemiptera (true bug)
Order Plecoptera (stone fly)
Order Trichoptera (caddis fly)
FIGURE 6.7
Common orders of insects. (Images from Australian Fresh Water Invertebrates. Available at
http://www.mdfrc.org.au/bugguide/resources/rr_clearedhills.htm.)
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