Evolution of nervous systems
Jellyfish, comb jellies, and related animals have diffuse nerve nets rather than a central nervous system. In most jellyfish the nerve net is spread more or less evenly across the body; in comb jellies it is concentrated near the mouth. The nerve nets consist of sensory neurons that pick up chemical, tactile, and visual signals, motor neurons that can activate contractions of the body wall, and intermediate neurons that detect patterns of activity in the sensory neurons and send signals to groups of motor neurons as a result. In some cases groups of intermediate neurons are clustered into discrete ganglia.
The Thing About Jellyfish
Suzy postulates that Franny's death was the result of Irukandji syndrome after Suzy learns about jellyfish on a field trip to an unnamed aquarium, which Benjamin states is the New England Aquarium in the end notes. While researching the subject, Suzy identifies the following real-life jellyfish experts she thinks could ask for help: