Table of contents
The current project is designed to improve access by scientists and educators to tools for identifying biodiversity in freshwater environments. Digital photographs organized and posted on the internet provide excellent resources for such a task. Such resources are available for few taxonomic groups and are generally incomplete in their coverage.
The Ostracode Project provides photographs for freshwater ostracodes. (In some sources, the name for the group is spelled “ostracod”, although “ostracode” is the preferred spelling.) Ostracodes are a class of the subphylum Crustacea. Most species are small (ca. 1 mm long) and live associated with the sediments in freshwater and marine environments. Because of their rich fossil record, paleontologists also study this group to examine evolutionary lineages and to explore the history of past lake environments. Although most currently-living species are marine, the freshwater ostracodes are diverse and quite common. The biology of the ostracodes is described in detail in other sources (Schram 1986, Meisch 2000, Delorme 2001).
We captured digital photographs of ostracodes from 56 different freshwater populations. These represent 38 species in 22 genera (Table 1), a significant fraction of the 36 free-living freshwater genera (Delorme 2001). We plan to add other taxa in the future as photos become available. Photographs in this web site can be accessed either through a collage or through species lists arranged alphabetically or by taxonomic rank (see task bar for links). A brief introduction to the identification of ostracodes is also available.
Material for the ostracode project was collected over a wide geographic range in the United States and Canada as part of previously-published studies (Havel and Hebert 1989, 1993; Havel et al. 1990a, 1990b; Havel et al. 2000). We collected mostly from freshwater ponds. Wherever possible, we photographed multiple populations of each species in order to illustrate variation in body form. Although a variety of benthic species are included, most of the species shown on this web site were collected with hand nets. Therefore, species restricted to deeper benthic environments and the sediment-water interface are under-represented in the current set of photos and species lists. We collected only free-living species, so we include none of the entocytherids, which live on the gills of crayfish (Delorme 2001).
We took color microphotographs using an Olympus Camedia C-5050 zoom digital camera (5.0 mega pixel) mounted with adaptors on a Wild-Leitz M5A dissecting microscope. For higher magnification, the camera could be moved to an Olympus B2 compound microscope. Specimens were placed in wet mounts, using “clay feet” to protect the specimen from the weight of the cover glass. The slide was elevated on a clear plastic lid and then illuminated either from the bottom or from the top and sides with a fiber optic lamp.
The camera was connected directly to a Gateway Pentium 4 computer for storing and manipulating the digital images. Images were analyzed with SigmaScan Pro 5.0 and Adobe Photodeluxe software, in order to extract extraneous objects, crop, rotate, optimize color and contrast, and add scale bars to the photos.
We thank Dr. Alison Smith for the suggestion to consult the Meisch (2000) reference and Dr. Denis Delorme for comments on the web site. Support for ostracode collections came from a Canadian NSERC grant (to P.D.N. Hebert) and a Missouri Department of Conservation grant (to J.E.H.). Later support for photography and web site design came from a Missouri State Summer Faculty Fellowship and partial support of a grant from the U.S. Environmental Protection Agency (EMAP program).
Delorme, L.D. 2001. Ostracoda. Pp. 811-849 in Thorp, J.H., and A.P. Covich (eds.).
Ecology and classification of North American freshwater invertebrates. Academic Press, San Diego.
Havel, J.E., E.M. Eisenbacher, and A.A. Black. 2000. Diversity of crustacean zooplankton in riparian wetlands: Colonization and egg banks. Aquatic Ecology 34: 63-76.
Havel, J.E., and P.D.N. Hebert. 1989. Apomictic parthenogenesis and genotypic diversity in Cypridopsis vidua (Ostracoda, Cyprididae). Heredity 62: 383-392.
Havel, J.E., and P.D.N. Hebert. 1993a. Clonal diversity in parthenogenetic ostracodes. Pages 353-368 in: McKenzie, K.G., and P.J. Jones (eds.). Ostracoda in the Earth and Life Sciences, Balkema Publishers, Rotterdam.
Havel, J.E., P.D.N. Hebert, and L.D. Delorme. 1990a. Genetics of sexual Ostracoda from a low arctic site. Journal of Evolutionary Biology 3: 65-84.
Havel, J.E., P.D.N. Hebert, and L.D. Delorme. 1990b. Genotypic diversity of asexual Ostracoda from a low arctic site. Journal of Evolutionary Biology 3: 391-410.
Meisch, C. 2000. Freshwater Ostracoda of Western and Central Europe. Süßwasserfauna von Mitteleuropa 8/3. Spektrum Akademischer Verlag, Heidelberg.
Schram, F.R. 1986. Crustacea. Oxford University Press, New York.
Web site posted: January 2005