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Re: NFC: Mystery shrimp (fwd)

> Date: Thu, 28 Jan 1999 23:32:34 -0700
> From: Tony <z966349 at niu_edu>
> Reply-To: Agustafs at niu_edu
> To: NFC <nfc at actwin_com>
> Subject: Mystery shrimp
> I'm hoping somebody here can answer this question which has plagued me
> for years. But first, the story...

Tony's mystery shrimp are likely to be isopods (genus Lirceus), which
are very closely related to amphipods such as Gammarus.  These have
fascinated me for years, so I will provide some extra information for 
those interested.

These isopods become very active under the ice as spring 
approaches--the first organisms to show much activity for the season. 
Put them in warm water and they begin a drastic mating frenzy 
involving fierce competition among the large males (up to about an 
inch), which are about three times the size of females.  Males find a 
female, crawl atop her and hang on desperately as other males try to 
strip them and take control of the female.  If a male can 
successfully guard its intended mate until she molts, he will 
fertilize her.  As well as struggling with other males, however, a 
male has to contend with female struggles to be released, which may 
serve as a form of female mate choice among males.  Once fertilized, 
the female's offspring hatch internally from the eggs into a brood 
chamber called a marsupium.  The young are "born" live from this 
chamber during the next molt. 

To keep them in home aquaria requires alot of leaf litter and other 
detritus, upon which the isopods feed.

Thom DeWitt

Dr. Thomas J. DeWitt

Address until March 1, 1999:
  Center for Ecology, Evolution, & Behavior
  TH Morgan School of Biological Sciences
  University of Kentucky
  Lexington, KY 40506-0225

tel 606/323-4992; fax 257-1717; email dewitt at ceeb_uky.edu

After March 1, 1999:
  Department of Wildlife & Fisheries Sciences
  Texas A&M University
  College Station, TX 77843-2258

E-mail tdewitt at wfscgate_tamu.edu