Nice pictures Ralph!! It is a bit hard to see because of the thick carapace of the waterflea but I believe these waterfleas have a loop in the gut.
I could not see the movie, Avi's don't always work well on the Mac.
It is always a nice trick to count the heartbeat of the waterflea. Becasue I have made some educational websites I often get questions from schoolchildren about science projects (most of them want me to make their homework:) and I suggest this method. One person has a stop watch to indicate4 1 minute and the other person taps with a pensil on a piece of paper in the right beat of the heart. After a minute you can count the dots and have the beats per minute.
