• 13 parts
  • Checked October 2026

Daphnia Heart Diagram

A water flea seen through its clear shell, with the heart and twelve more parts labeled.

Daphnia Heart Diagram

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1 2 3 4 5 6 7 8 9 10 11 12 13
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Write the name of each numbered part.Answer key

  1. Heart
  2. Compound eye
  3. Antennae
  4. Carapace
  5. Intestine
  6. Brood chamber
  7. Eggs
  8. Legs
  9. Head
  10. Postabdomen
  11. Claws
  12. Ocellus
  13. Antennules

Drawn for this site on 2026-10-01 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: a larger crustacean, the crayfish

All 13 parts on the diagram

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Water flea 13

  1. Heart A small sac on the back, just past the head.
  2. Compound eye One large dark eye. Small muscles turn it.
  3. Antennae Large branched arms. The animal swims with them.
  4. Carapace A clear, folded shell. It covers the body and the legs.
  5. Intestine Food can be seen passing along it. It ends on the postabdomen.
  6. Brood chamber A space under the back of the shell. A female carries her eggs in it.
  7. Eggs The female carries them under her shell.
  8. Legs Flat, leaf-like legs fringed with bristles.
  9. Head It carries the eye and both pairs of antennae.
  10. Postabdomen The last part of the body. It ends in two claws.
  11. Claws Two small hooks at the tip of the postabdomen.
  12. Ocellus A tiny spot that senses light.
  13. 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

This daphnia heart diagram shows a water flea from the side, as a microscope shows it through the clear shell. The heart is number 1: a small sac on the back, just behind the head.

Read the full guide

Find the heart first

Look along the back, just below the head. The heart is the small rounded sac in front of the brood chamber, the long space that holds the eggs. The intestine is the long tube beside them: it loops through the head and runs down to the postabdomen.

The rest of the water flea

The head carries the large compound eye, the tiny ocellus, the antennules and the large branched antennae. The carapace is the clear shell round the body. Flat, leaf-like legs lie at the front, and the postabdomen ends in two claws. Press Quiz me to name each part.

  • Under a microscope, the heart is the small sac near the back that can be seen beating.

Questions and answers

Where is the heart of a Daphnia?

On the back, just past the head. The shell is clear, so the heart can be seen beating under a microscope.

Why is Daphnia called a water flea?

Because of the way it swims: in short jerks that look like the jumps of a flea. A Daphnia is a small crustacean, not an insect.

How many eyes does a Daphnia have?

One large compound eye, which small muscles turn. Many species also have an ocellus, a tiny spot near it that senses light.

What is the brood chamber of a Daphnia?

A space between the body and the back of the shell. A female carries her eggs there.

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