picture of fish from:

http://www.shadesofblue.com/pages/uwimages.html

 

Daphnia, or "water fleas", are small freshwater crustaceans found all over the world. They are quite common in lakes, streams, and ponds. They are usually less than 3mm in size, meaning one could fit dozens of them on a fingernail. These tiny crustaceans are extremely important to the food chain in lakes, rivers, and streams. Daphnia harvest small algae cells which convert sun energy into food, which is passed along to their predators. Daphnia can be used as filter feeders and eat a large variety of small organisms such as euglena, protozoa, bacteria, and yeast. They can also be used to clear the green water of ponds or aquariums.

Daphnia can best be cultured in a laboratory while being well fed and receiving frequent water changes. To keep them from reproducing quickly, keep them in a refrigerator. Each pregnant daphnia can deliver up to fifteen babies every three days. Once they start reproducing they quickly outgrow the capacity of their container, be careful!

Their body is divided into three sections, the anterior head, the middle thorax, and the posterior abdomen. Both the middle thorax and the posterior abdomen are enclosed by the carapace, but the head is not. The carapace is a double fold of body wall. The head extends outside of the body. Located in the head are the compound eyes, which are movable. The mouth is also located in the head, but is impossible to see through our microscope. The thoracic region is what makes up most of the body. Located in the thoracic region is the oval heart. One can easily see it beating through a microscope. Daphnia swim in a jerky motion. They have five pairs of legs inside their body which are used to capture their food.

 

Bibliography for this mini-essay

Biomedia Associates. "Daphnia-the Water Flea". (Online) Available

http://ebiomedia.com/gall/classics/Daphnia/daphnia_gen.html, 2001.

 

Biomedia Associates. "Swimming, Feeding, and Breathing". (Online) Available

http://ebiomedia.com/gall/classics/Daphnia/daphnia_behave.html, 2001.

 

Fox, Gary. "Invertebrate Anatomy: Daphnia Magna" (Online) Available

http://www.lander.edu/rsfox/daphnia.html, 1994.

 

Henderson, Gary. "Culturing Daphnia". (Online) Available

http://www.thekrib.com/Food/0, August 11, 1994.

 

Unknown. "Daphnia magna" (Online) Available http://www.lfscultures.com/p12.html, no

date.

 

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