Zooplankton of the Great Lakes

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Organism: Diaphanosoma spp.


Kingdom: Animalia

Phylum: Arthropoda

Class: Branchiopoda

Order: Cladocera

Family: Sididae

Genus: Diaphanosoma



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Figure 1. Diaphanosoma spp. preserved in a classic ventral view.


Diaphanosoma is distinguished by having a compound eye in the middle of its head. It has long second antenna with two branches. The body is entirely covered by a carapace. They have many setae arrange in a row along the large 2nd antennae.  (Balcer et al 1984). The most distinguishing characteristic of the  Diaphanosoma is the second antennae. Which are longer than the body and when preserved often are sticking out to the side as in figure 1.  The North American species have several distinguishing characteristics including an elongated body without terminal shell spines. They also have rounded heads and do not have a crest on their head. The second antennae can reach the posterior margin of the carapace.  (Balcer et al 1984) and Brooks (1959). The females can grow between 0.8 mm and 1.2 mm in the Great Lakes. (Brooks 1959).

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Figure 2. The setae along the second antennae.

Distribution and Habitat:

The distribution of Diaphanosoma is from the Arctic Circle to the U.S. state of Louisiana in North America. It can also be found in Europe, Asia. With some species being found in South and Central America. With a species also being found in Africa. There are only two species in the Great Lakes region. D. birgei and D brachyurum.  (Balcer et al 1984)


Feeding Ecology:

Gliwicz (1969) found that Diaphanosoma is a filter feeding species and is able to intake particles up to 154 um.  With a preference on chlorophytes and diatoms.  Kerfoot (1991) states that smaller cladocerans including Diaphanosoma are able to show some selection for taste and some discrimination based on size.


Life History/Reproductive Growth:

Diaphanosoma spp. usually reproduces using parthenogenesis. Almost all Diaphanosoma are females unless they are specially created males that are only created when a stimulus enters the aquatic system. When the female Diaphanosoma receives a stimulus signal in the system the Diaphanosoma females will create diploid male eggs, which will hatch and then fertilize haploid eggs from the females. These, eggs are specialized to hatch only when conditions are right and are called ephippial eggs(Balcer et al 1984). For a diagram of the Reproductive growth of Diaphanosoma view figure 3. 

In the Great Lakes this Genus is consumed by multiple species of fish including largemouth bass and yellow perch. (Balcer et al 1984).

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Figure 3. The Reproductive cycle of Diaphanosoma spp.


Figure 4. A lateral view of Diaphanosoma spp.

 Works Cited:

Balcer, M.D., Korda, N.L., Dodson, S.I.1984.Zooplankton of the Great Lakes: A guide to the identification and ecology of the common crustacean species, pp. 5-7, pp. 54-56. The University of Wisconsin Press, Madison.

Brooks, J.L. 1959. Cladocera. In Fresh-water Biology, 2nd ed., W.T. Edmonson, ed, pp. 587-656. John Wiley and Sons.New York.

Gliwicz Z.M. 1969. Studies on the feeding of pelagic zooplankton in hte lakes of varying trophy. Ekol. Pol. Ser. A. 17:663-708.

Kerfoot, W.C., Kirk, K.L. 1991. Degree of taste discrimination among suspension feeding cladocerans and copepods: Implications for detritivory and herbivory. Limnol. Oceanogr.36: 1107-1123.