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Daphnia
Form and Structure
*See illustrations of "summer eggs," which develop partheno-
genically, and "winter eggs," which develop after being fertil-
ized. Winter eggs have a thick shell and are produced in smaller
numbers; the brood chamber is molted to form a protective
ephippium.
Diagrammatic
Representation of Position
of "Summer Eggs"
31. "Summer eggs"
Diagrammatic
Representation of
Ephippium and Position
of "Winter Eggs"
32. "Winter eggs"
33. Ephippium
Diagrammatic Anatomy of a Female Daphnia
1. Frontal organ
2. Esophagus
3. Antennal adductor muscles
4. Antenna
5. Antennal levator muscle
6. Heart
7. Ovary
8. Blood Chamber
9. Thin-shelled "summer eggs"*
10. Abdominal process
11. Apical spine
12. Post abdomen
13. Post abdominal claw (paired)
14. Anus
15. Rectum
16. Carapace
17. Filter setae
18. 2nd and 3rd thoracic
appendages
19. Shell gland
20. Maxillae (vestigial)
21. Mandible
22. Mouth
23. Labrum
24. Antennule
25. Rostrum
26. Hepatic cecae
27. Ocellus or nauplius eye
28. Optic ganglion
29. Compound eye with
optic nerve
30. Nuchal or neck organ