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Daphnia (or the multiplication tables)
I keep two strains of Daphnia pulex (females of type a are about 2 mm in
length, females of type b are between 2.5 and 3.5mm in length). I decided
to carry out a little experiment on type a. I took an adult female and put
her in a jar of water (about 300ml) rich with algae last Tuesday (18th)
evening. The next morning there were about 10 tiny daphnia in the jar
along with the mother. On Friday night/Saturday morning the mother
produced another ~10 tiny daphnia, and today (Monday the 24th) it's
impossible to tell the mother from the first generation of offspring. This
first generation are all carrying embryos too. I kept the jar at about
19-20 degrees Celcius (inside temperature of the house). I know a lot
about Daphnia (I've studied them on and off for the last few years) but I
have never tested their powers of reproduction so precisely. Did you know
that most members of the genus Daphnia put about 70% of their energy into
reproduction and only 23% into growth? I can't help admiring these
animals, even if all I do is feed them to my fish!
PS: I'm going to order some D. magna from LFS cultures since I can't
get hold of anything but pulex (even though they'll take a week to get
here). Has anyone ordered from them before and if so I'm curious as to how
they package their water-born cultures?
"Language has not the power to speak what love indites:
The soul lies buried in the ink that writes."
eirinn at valhalla_com (http://www.maths.tcd.ie/~jpc)