Daphnia  -  water fleas

Phylum:   Arthropoda

Class:   Crustacea

Sub-order:   Cladocera

Daphnia are commonly known as Water Fleas due to their size, shape and movement.  They are found in ponds and waterways.  Their transparent shell covers their legs and pointed spine, and in some cases, the shell also covers the head.  Distinctive feathery antennae stand stiffly outstretched.  These allow Daphnia to move in a zigzag motion as they feed on suspended bacteria and green protists.

Daphnia reproduction is parthenogenic (eggs develop without being fertilized).  Eggs undergo development in a brood chamber and hatch there as fully developed young.

Open water Cladocerans undergo a vertical migration during each 24 hour period.  These drifting populations commonly move upward with the onset of darkness and downward with the coming of dawn.

Image courtesy of Carolina Biological Supply Company

Click here to download care instructions (pdf, 0.1M, new window)

Read about a procedure that uses Daphnia as a model for studying the effect of caffeine on heart rate (new window).

Read about a student experiment on the effect of light on Daphnia behaviour (new window).

Download a movie file that shows a water flea magnified 40X - opens in a new window, mp4 file, 1M, opens with QuickTime or iTunes (may be played on a video iPod).  (Movie by A Watts)

Download the free Quicktime player