The functional body cavity is a spacious hemocoel divided by a horizontal diaphragm into a dorsal pericardial sinus and a much larger perivisceral sinus. Extant arthropods exhibit regional specialization in the structure and function of segments and appendages but the ancestor probably had similar appendages on all segments.
The abdomen can be straightened to extend posteriorly from the carapace. The regions of the intestine filled with food are easily seen and are likely to be green with phytoplankton or brown with dried cladoceran pellets.
The abdomen and its claws are used to clean the thoracic appendages and remove blockages, such as filamentous algae, to the filter feeding apparatus. Such eggs may be enclosed in a purselike ephippium that rests in the sediment at the bottom of the lake or pond until the resting eggs hatch into parthenogenetic females.
The two compound eyes are fused on the midline. An atlas of invertebrate structure. Winter eggs hatch in the following spring. When you have secured a cladoceran in the jelly, carefully add lake water until the animal is immersed.
The ephippium is released when the female molts. A glossary and chapters on supplies and laboratory techniques are also available.
Motionless Daphnia sink rapidly to the ground.