MadSci Network: Zoology |
Daphnia do not have contractile vacuoles. Contractile vacuoles are pretty much limited to some protists and sponges. Daphnia, being crustaceans in the Phylum Arthropoda (Kingdom Animalia), have a complex, kidney-like organ built upon basic units called metanephridia. I did a simple search on "daphnia osmoregulation" and came up with the following URL which has some good, basic information on osmoregulation in animals in general.
www.springerlink.com/index/H51455X32L070485.pdf
Hope this has been useful.
Try the links in the MadSci Library for more information on Zoology.