A whole new collection of deep-sea dwellers has recently been discovered at a depth of more than 4,500 metres in the Indian Ocean to the west of Australia. Among them, researchers have found some thirty new species and, what’s more, the longest animal ever recorded: a siphonophore over 40 metres long.
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The existence of creatures of extraordinary proportions has captivated humans since ancient times, a fascination fed both by the myths about the origin of the world peopled by giants of all sorts —common to various cultures— and by the discovery of the remains of beings of enormous dimensions.
Thus, the Greek historian Herodotus wrote about the discovery of the supposed bones of the giant Pallas and the enormous hero Orestes. The Roman naturalist Pliny the Elder also left testimony about the discovery of the bones of another mythological giant, Orion, on the island of Crete. Similar accounts followed in antiquity in Europe, Asia and the Americas. Later, the Church and large fossil remains made strange bedfellows: some were attributed to biblical characters and venerated as relics in temples. For example, in the church on which St. Stephen’s Cathedral was built (in Vienna), a mammoth femur was preserved, believing it to be that of a giant who died in the biblical flood. Also in Austria, the monastery of Wilten used to house the bill of a swordfish, which was said to be the tongue of the dragon defeated by the mythical giant Haymon.
All that changed from the 17th century onwards, with the emergence of modern science based on experimentation, observation and comparison. Through comparative anatomy, the naturalists demonstrated that those stories about giants were nothing more than that, myths and legends, and that the colossal bones attributed to them actually belonged to whales, elephants and other animals (many of them now extinct). However, this did not dilute the fascination with giants that today still accompanies every new fossil find of a gigantic dinosaur, and every discovery of a new species of giant that had hitherto remained hidden from humans, something that, incredible as it may seem, is still happening in the 21st century.
The marine behemoths
The most propitious habitat for finding new giants today is in the depths of the ocean. While the largest land animal is the African elephant (10 metres long) and the tallest, the giraffe (reaching over 6 metres high), these giants are far from the proportions of the marine behemoths: the largest fish is the whale shark (12 metres), and the giant squid reaches a length of 14 metres, surpassed by the 16 metres (and more than 45 tons) of the sperm whale or the unapproachable 30 metres of the blue whale, the largest animal ever known on Earth (bigger than the largest of the dinosaurs).
Colonies of marine organisms, such as the newly discovered siphonophore, can exceed these giants in length. The largest living organism on the planet has also been identified in the ocean, a colony of Posidonia oceanica seagrass located to the south of the island of Ibiza, covering an area of 8 kilometres.
And all this when we hardly know anything about the deep sea. NASA’s Magellan space mission managed to map 98% of the surface of Venus at a resolution of 100 metres. Over 60% of the Martian surface has been mapped at a resolution of 20 metres. The entire surface of the Moon has been explored at a resolution of 7 metres. What about the oceans?
Since 2014, we have had a complete map of the entire ocean floor at a resolution of 5 kilometres. Below these dimensions all the reliefs and underwater features remain hidden, as the water absorbs the radar waves. To see them in more detail, it is necessary to use sonar (with a much shorter range) and underwater robots. Within the immensity of the ocean, the abyssal depths are a barely explored ecosystem and, therefore, the place on the planet that is most conducive to encountering new species of gigantic size.