Daphnia Image Labeling – Water Flea Worksheet and Key

All 13 parts on the diagram

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Water flea 13

Heart A small sac on the back, just past the head.
Compound eye One large dark eye. Small muscles turn it.
Antennae Large branched arms. The animal swims with them.
Carapace A clear, folded shell. It covers the body and the legs.
Intestine Food can be seen passing along it. It ends on the postabdomen.
Brood chamber A space under the back of the shell. A female carries her eggs in it.
Eggs The female carries them under her shell.
Legs Flat, leaf-like legs fringed with bristles.
Head It carries the eye and both pairs of antennae.
Postabdomen The last part of the body. It ends in two claws.
Claws Two small hooks at the tip of the postabdomen.
Ocellus A tiny spot that senses light.
Antennules A pair of small feelers that carry sense hairs.

How this list was compiled: Every name checked on 2026-10-01 in at least two of three places. (1) Wikipedia: Daphnia, Cladocera, Daphnia magna, https://en.wikipedia.org/wiki/Daphnia. (2) Animal Diversity Web, University of Michigan Museum of Zoology, Daphnia pulex, https://animaldiversity.org/accounts/Daphnia_pulex/. (3) E. A. Birge, The Water Fleas (Cladocera), in H. B. Ward and G. C. Whipple, Fresh-Water Biology (1918, public domain), https://archive.org/details/freshwaterbiolog00ward. Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

For daphnia image labeling, write a name on the line for each number. The water flea is a female, drawn from her left side with her head at the top.

Read the full guide

Daphnia labeling word bank

In alphabetical order: antennae, antennules, brood chamber, carapace, claws, compound eye, eggs, head, heart, intestine, legs, ocellus, postabdomen.

Where each number ends

Down the left side: 2 ends on the large black disc, 12 on the small spot below it, 13 on the short rod at the point of the head, 8 on a leaf-shaped limb and 11 on the black hooks. Down the right: 3 ends on the thick branched arm, 1 on the small round sac, 7 on one of the four round bodies, 6 in the space around them, 5 on the long tube and 4 in the empty foot of the shell. 9, at the top, ends above the disc; 10, at the bottom, on the broad curved band.

When marking, second antennae is right on line 3, shell on line 4, gut on line 5 and brood pouch on line 6.
The spine at the foot of the shell and the far antenna, in thin lines behind the head, are drawn, but have no number.
The claws, number 11, are for cleaning: a Daphnia uses them to clear debris out of its shell.

Questions and answers

What do Daphnia eat?

Mostly single-celled algae, with bacteria and bits of dead matter. A Daphnia is a filter feeder: its legs, number 8, keep beating and draw a current of water through the shell, and the food in it goes on to the intestine, number 5.

Is the Daphnia on the worksheet male or female?

Female: numbers 6 and 7 are her brood chamber and the eggs in it. Males are generally smaller, with longer antennules. In summer a population is almost all females, whose eggs grow into young without a male.

Where do Daphnia live?

Mainly in fresh water, from lakes and ponds to acidic swamps; a few species live in the sea. They are too small and weak to swim against a strong current.