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Re: Live Foods Digest V2 #228
I am familiar with Pennak's book (thanks to that library), and I'm well
aware of the pulsing phenomenon in Late Spring and in Autumn. I will have
a look for any papers on ephippia to try and clarify it for myself, but I
get the distinct impression that by and large for most species there is
only one kind of ephippium and this is produced when a female is
fertilized by a male, no matter what time of the year as it is simply
dependent on the presence of males, which in turn is dependent on
On Sat, 17 Oct 1998, George Slusarczuk wrote:
> Hello John,
> It is fortunate, that you have access to a good academic library -- I
> miss that sorely!
> Right now I can't lay my hands on the "two kinds of ephippia" paper(s).
> But in a good library you will have access to Biological Abstracts,
> perhaps even have them online, so searching for "ephippium" and/or
> "daphnia" will get you these papers.
> There was a spate of publications about 10-15? years ago. One
> interesting paper was from Leningrad, Russia. The authors did
> experiments on the freeze/thaw cycles, using a local strain of a
> cladoceran, can't remember which. Several Finnish workers also did work
> in that area.
> Closer to home, R.W. Pennak in his "F-W Invertebrates of the US" refers,
> in several places, to spring and fall maxima in cladoceran populations
> and that males tend to appear in late spring and fall. Males = ephippia.
> If you find out more detail on this subject, please share. For the last
> 5 years or so, I did not try to keep abreast in that field.