I found these beautiful Daphnia at the weekend, though over 24 hours their numbers diminished greatly because there were two predatory Dytiscus larvae in the jar (see bottom photo).  Emily and I took them all for a trip into the Gayhurst classroom today to do some more research, I think a few of them might still be there on the desks as it was quite fiddly getting them from the jar to the petri dish and back.