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📘 Where does a jellyfish decide to swim?

The book opens with the seaside scene before it opens the laboratory. Romanes calls jelly-fish and star-fish

4
lessons
~20 min
to learn
Adults
level
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What you’ll learn

  1. Medusa as a visible machineUse the medusa’s beat as an experimental window on excitability.Covered eyes and decisive cuts frame the method.
  2. Rhythm, stimulation, and the nerve-ringTest coordination without assuming a brain.Natural vs artificial rhythm; the nerve-ring hypothesis.
  3. Poisons, evolution, and star-fishRead pharmacology and evolutionary claims with care.From jelly-fish to star-fish rays that keep acting.
  4. Urchins, limits, and an open doorHold what Romanes got right; leave one tide-pool question open.Urchin apparatus; notice today, revise tomorrow.

Questions this course answers

Why does Romanes treat the medusa as an important experimental animal?

The bell's coordinated contractions make changes in initiation, conduction, and rhythm observable.

What happens when Romanes removes the extreme margin of a naked-eyed medusa?

The result supports the presence of localized centres of spontaneity in the margin.

Why does Romanes study both naked-eyed and covered-eyed medusae separately?

Comparative physiology must follow the structure of each animal rather than impose one diagram on both.

What does Romanes mean by a natural rhythm?

His mutilation experiments suggest spontaneous activity is also modulated by afferent influences from other tissues.

What is the purpose of the poison experiments?

Agents such as chloroform, alcohol, and curare probe physiological properties, not folklore about venom.

What does the starfish section add to the medusa argument?

Starfish and sea-urchins require a different account of coordinated action because their bodies and locomotor organs differ.

Grounded in trusted sources

  • Jelly-fish, Star-fish, and Sea-Urchins: Being a Research on Primitive Nervous Systems (1885), full scan and OCR, Biodiversity Heritage Library, https://www.biodiversitylibrary.org/item/201570
  • Jelly-fish, Star-fish, and Sea-Urchins (1885), digitized volume, Internet Archive, https://archive.org/details/jellyfishstarfis00roma_0
  • The life and letters of George John Romanes, account of the medusa experiments, Project Gutenberg, https://www.gutenberg.org/files/49182/49182-h/49182-h.htm
  • Dictionary of National Biography: Romanes, George John, Wikisource, https://en.wikisource.org/wiki/Dictionary_of_National_Biography%2C_1885-1900/Romanes%2C_George_John
  • Prof. Eimer on the Nervous System of Medusae (1878), Nature, https://www.nature.com/articles/017200a0
  • George John Romanes, Jelly-fish, Star-fish, and Sea-Urchins (1885), BHL, https://www.biodiversitylibrary.org/item/201570
  • Biodiversity Heritage Library portal, https://www.biodiversitylibrary.org/
  • Britannica, Nervous system, https://www.britannica.com/science/nervous-system

Every Wunder lesson is built from real, reputable sources — never invented.

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