Hembra de pulga de agua, identificada históricamente en la imagen como Daphnia vetula - Ilustración de stock

The Organism: Water fleas are small planktonic crustaceans. The large, branched structures at the top are the second antennae, which the animal uses for swimming with a characteristic "jerky" motion.Anatomy:The large dark "hook" shape running through the center is the intestine.The circular shapes clustered at the back (left side of the body) are eggs resting within the female's brood pouch.The large dark spot at the front of the head is the compound eye.