CORPS OF ENGINEERS DETROIT MI DETROIT DISTRICT
Pagination or Media Count:
A field biologists attempting to identify mussles, especially endangered species, must depend on the use of shell features. This is not surprising since mussel species were and still are described by use of shell characteristics Heard 1979. However, soft anatomy is also important in defining higher taxonomic groupings such as family and subfamily. Occasionally, characteristics of the soft anatomy are useful in the field and laboratory to separate mussles with similar shell features. In any group of organisms, variation of identifiable features causes difficulties for beginners as well as professionals. In the mussles, variation in shell morphology can be caused by several factors including varying genetic stocks, age, sex shell sexual dimorphism, stream station, and differences in physical or chemical parameters. With experience, however, a field biologist should be able to accurately identify mussles despite shell variation. Certainty of identification is needed not only for scientific accuracy, but also because of legal requirements of the Endangered Species Act. Many salient external and internal shell features important in identifying mussels are included in the attached outline.