The Book of Eels | Patrik Svensson

Summary of: The Book of Eels: Our Enduring Fascination with the Most Mysterious Creature in the Natural World
By: Patrik Svensson


Dive into the mysterious world of eels with ‘The Book of Eels’ by Patrik Svensson, as it chronicles the fascinating life cycle of these enigmatic creatures. Discover the four stages of development eels undergo as they migrate across the Atlantic and the various transformations they experience throughout their lives. The book also delves into the relationship between humans and eels throughout history, from being considered as demons by ancient Egyptians to the scientific interests of Aristotle. This captivating narrative explores the role eels play in various ecosystems, as well as the threats posed to their survival by human activity and climate change.

The Fascinating Life Cycle of Eels

Eels are more than just slimy, black fish. They have a complex life cycle that includes four stages of metamorphosis. From their birth as Leptocephalus larvae in the Sargasso Sea, eels make a journey across the Atlantic, undergoing multiple transformations. They become glass eels, yellow eels, and finally, sexually mature silver eels. The journey back to the Sargasso Sea is their final voyage, where they fertilize their eggs and die. Despite their unusual appearance and behavior, eels remain a remarkable and fascinating species.

Aristotle and the Enigma of Eel

The scientific interest in eels dates back to Aristotle, who described the fish’s anatomy in detail, but also made fanciful claims, such as their ability to live on land. He also proposed that eels emerged from mud, a theory that puzzled scientists for centuries. Aristotle’s work on the eel created an enigma that scholars call “the eel question,” which remains a mystery even after two thousand years.

The Elusive Sexuality of Eels

After centuries of research, scientists finally discovered the reproduction secrets of eels. The Italian physician Francesco Redi was the first one to conduct an experiment that challenged the belief that flies could spontaneously spawn without fertilized eggs. It took another century to find out that eels can lay eggs. Later, a professor discovered the reproductive organ and eggs of a female eel, but the male anatomy remained a mystery until 1874 when Italian researchers speculated that they had found a lobe that could be the missing testicle. They sent a young student named Sigmund Freud to investigate, who failed to identify the lobe, but unbeknownst to him, eels only develop sex organs when they need them. The discovery of a sexually mature male silver eel twenty years later ultimately solved the mystery. Freud’s investigation marked the beginning of his intense interest in the concealment of sexuality.

The Eel’s Mysterious Birthplace

Danish biologist Johannes Schmidt spent almost 20 years tracing eel migration, finally discovering their spawning grounds in the Sargasso Sea, which remains an enigmatic mystery.

Eels are fascinating creatures that have been puzzling scientists for centuries. By the twentieth century, one of the most significant questions related to them was where do they breed? Danish biologist Johannes Schmidt aimed to answer this question and embarked on a journey that spanned almost two decades.

Before Schmidt, scientists believed that eels migrated from Europe to the Mediterranean to breed, but this theory didn’t account for the size of the larvae found in the Mediterranean. Schmidt believed that tracing eel larvae back to their birthplace was the key to solving the enigma. He planned to measure the sizes of these larvae at different locations, the smaller larvae indicating a closer proximity to their spawning ground.

Schmidt sailed up and down the coasts of Europe for seven years, but his efforts led to no substantial breakthroughs. It was not until he sailed west towards the Americas that his luck changed. The further he got from Europe, the smaller the larvae he found became.

After nine more years of perseverance, Schmidt finally discovered what he had been searching for in the Atlantic’s Sargasso Sea. The larvae he found there were so minuscule that they must have been newly hatched, and Schmidt had discovered the eel’s birthplace.

Thanks to Johannes Schmidt’s hard work and determination, we now know that eels undertake a grueling migration of over five thousand miles to breed in the Sargasso Sea. However, the answer to why eels undertake such arduous journeys still eludes scientists.

In conclusion, Schmidt’s efforts were not only a significant contribution to science, but they also revealed the mesmerizing mystery surrounding the eel’s birthplace, which still intrigues people to this day.

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