Home > NEWS & MEDIA > News and Events > Hyalonema controversy and the construction of ocean knowledge

Hyalonema controversy and the construction of ocean knowledge

The origin of oceanography is often traced back to the famous British H.M.S. Challenger expedition of the 1870s. Daniel Gamito-Marques, InsSciDE researcher in Science Diplomats, participated in a panel on the history of knowledge of the deep sea and suggested international scientific exchanges in the years prior provided crucial information for the organization of the expedition.

This article is based on a presentation by Daniel Gamito-Marques in the panel ‘Assembling the seafloor’ at the British Society for the History of Science Postgraduate Conference on 14 April 2021. It was organized by him and the two other speakers in the panel, Erik Isberg (KTH Royal Institute of Technology, Stockholm) and Beatrice Martínez-Rius (Sorbonne University, Paris).

Watch the recording to hear Daniel and the others’ fascinating presentations

Knowledge of the deep sea and its marine life was extremely limited in the early 19th century. Edward Forbes, one of the first to perform carefully planned dredging, observed that the deeper he went, the fewer species he found. In the 1840s, he proposed the Azoic hypothesis, suggesting that life would be impossible at great depths, due to the ocean’s high pressures and low temperatures.

In the 1860s, there was already evidence that conflicted with the Azoic hypothesis, but it remained commonplace in the absence of further detailed studies. A discovery by the Portuguese naturalist (and future science diplomat) J. V. Barbosa du Bocage contributed to an ultimate shift in the discussion. Bocage received a bizarre animal specimen found off the Portuguese coast by shark fishermen. He concluded that it belonged to the genus Hyalonema, and named it H. lusitanicum. The finding was remarkable, since it had until then only been found thousands of miles away, off the coasts of Japan and California.

Bocage helped to circulate Hyalonema specimens across Europe because he had easy access to them, thus enabling comparisons and stimulating debate around their identity. The species’ unusual structure – crystalline fibers twisted like a rope attached to polyps, and sometimes associated with a sponge on one extremity – became a point of intrigue to naturalists who could not agree if the animal was a coral or a sponge.

In 1868, Hyalonema was also discovered off the coast of Norway and in the North Sea. This time, it was found to also have a set of fibers covered in mud, which gave way to the idea that these were roots that fixed it to the ocean floor, and the previous specimens analyzed were damaged fragments rather than the entire animal.

Bocage’s action attracted the attention of European naturalists, such as Perceval Wright, a professor at Trinity College in Dublin, who visited Portugal during the shark fishing season. Not only did his dredging present the first intact specimen of H. lusitanicum from the region, confirming recent observations in the North Sea, but he also observed that the sharks were actually being caught at the same great depth. This was a remarkable observation, since up until then only invertebrates had been retrieved from such depths, and it provided a more complex picture of the sea bottom.

Other expeditions were organized in the following years, such as the H.M.S Lightning in 1868 which yielded an unprecedented collection of systematic data from across great ocean depths. The discoveries made by Portuguese and Scandinavian naturalists inscribed these two lesser-known sites of scientific research on the route of larger expeditions.

By being inserted in transnational scientific networks, Bocage contributed to the construction of knowledge about Hyalonema and deep-sea marine life. The Hyalonema controversy and its related discussions can be regarded as important steps in the lead-up to the groundbreaking H.M.S Challenger expedition. The famous expedition resulted in the discovery of about 4,700 new species of marine life between 1872 and 1876 and constitutes the founding event of modern oceanography. The journey included a stop in Lisbon, where Bocage’s scientific colleagues visited the National Museum of Lisbon to admire its zoological collections.

The international attention and scientific prestige accrued by Bocage thanks to the Hyalonema case and his other studies on African fauna played a part when he became involved in politics in the 1880s, favoring his appointment as Portuguese Minister of Foreign Affairs. Bocage’s international reputation as a scientific expert and his regular contact with foreign colleagues made him a good candidate for a position in which he had to use diplomacy to navigate national and global contexts. Read more about the 19th century naturalist’s career and activities at the nexus of science and diplomacy.

19 May 2021
Daniella Palmberg and Daniel Gamito-Marques

Assembling the seafloor webinar
14 April 2021
British Society for the History of Science Postgraduate Conference


  • Daniel Gamito-Marques (NOVA University Lisbon) | Researcher in InsSciDE Science Diplomats
  • Erik Isberg (KTH Royal Institute of Technology, Stockholm)
  • Beatrice Martínez-Rius (Sorbonne University, Paris)