ABSTRACT
Identifi cation of species is based on a systematic approach. Freshwater macroinvertebrates, which are normally used for water quality assessment, are only found in four phyla: the Annelida, Mollusca, Platyhelminthes and the Arthropoda. Each phylum is further broken down into classes then orders, families, genera and then individual species. For example, the common pollution-tolerant mayfl y Baetis rhodani is classifi ed as:
Phylum: Arthropoda Class: Insecta Order: Ephemeroptera Family: Baetidae Genus: Baetis Species: Baetis rhodani
You will notice that both genera and species names are always shown in italics. Table 4.1 shows the taxonomic groupings of all the commonly encountered freshwater macro-invertebrates.
