==References==* Moore, Janet (2001) "An introduction to the invertebrates" (Studies in Biology) Cambridge University Press, Cambridge, UK, ISBN 0-521-77076-9;* Thoney, Dennis A. and Schlager, Neil (eds.
* Moore, Janet (2001) "An introduction to the invertebrates" (Studies in Biology) Cambridge University Press, Cambridge, UK, ISBN 0-521-77076-9;* Thoney, Dennis A. and Schlager, Neil (eds.