Water-flea anatomy - by Wim van Egmond
close-up of the heart

The heart of a water-flea can be seen as a transparent sac right above the eggs. It is great fun to see it beating. A nice trick to count the heart beat rate is by tapping a pencil to the pace of the beat. After a minute of counting the taps, you can say how many times per minute the heart beats. 

The triangular muscle (top right) operates the powerful second antennae used for swimming. The gut contents are yellow-brown.

Apart from the unfertilised eggs you can sometimes find winter eggs.

darkfield Daphnia
brightfield Daphnia
head and eyes
ovary and embryos
frontal view


All comments to the author Wim van Egmond are welcomed.

Visit Wims home page for links to his many web pages on microscopy

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Published in the March 2002 edition of Micscape Magazine.

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