The giant squid, still little known and surrounded by mysteries, remains a fascinating animal for both the general public and scientists.
The mention of legendary sea monsters in ancient texts dates back to the mists of time. In ancient times, Homer confronts the great navigator Ulysses with Scylla, a creature whose description could be that of an animal close to the giant squid. Pliny the Elder, a first century Roman naturalist writer, reported the testimony of fishermen describing a real giant squid washed up on the coast of Malaga.
The legend of a sea monster lasted centuries. In the Middle Ages it was shown with the Kraken, a kind of giant octopus capable of swallowing a whole sailing ship described by the Swedish Bishop Olaus Magnus.
Admittedly, these seafaring peoples, otherwise inclined to superstition, often sailed through rough, hostile and dark seas, where it was not difficult to confuse real beings with strange animals and gigantic creatures.
Confirmation of its real existence
With the capture of large cetaceans, parrot beaks (horny jaws of cephalopods) were found in the stomach of sperm whales, and they were stored in museums. At the same time, giant squid stranded on the coast became the object of study of some researchers. And it is from these samples, in 1857, that the Danish scientist Japetus Steenstrup described the first giant squid which he called Architeuthis dux (the prince of the squid), a name that is still valid today.
Disclosure of the find remains quiet, but numerous strandings, particularly off the coast of Newfoundland in the 1870s, confirmed the real existence of the giant squid.
Did your legend take a hit for this reason? Not at all!, was willingly revived from the pen of the novelists of the time, and, later, thanks to the seventh art. From the beginning (1869), from the most famous attack on the Nautilus by a giant cephalopod in Jules Verne’s 20,000 Leagues Under the Sea, to the enigmatic Davy-Jones in the Pirates of the Caribbean movie saga in the 21st century.
In the giant squid everything is big
We are talking about the largest invertebrate on the planet. Paradoxically, it is also one of the least known, although its distribution is cosmopolitan.
This cephalopod lives inconspicuously between 200 and 1,600 meters deep. Our knowledge of its morphology and anatomy comes from coastal strandings and, more recently, from occasional catches by deep-sea fishermen in their large trawl nets.
Currently, it is estimated that most Architeuthis measure between 10 and 12 meters in total length (tentacles included), although it could reach up to 18 meters and weigh between 230 and 250 kilos.
Its anatomy does not present significant differences with its small congeners offered in the stalls of the fishmongers.
The eye the size of a basketball
We can remember three organs of striking size. The eye is the largest in the entire animal kingdom. About the size of a basketball, it has a retina extremely rich in visual cells. An asset to detect the approach of the sperm whale, its great enemy? Yes, but not directly. It can detect the arrival of the predator at a hundred meters thanks to the light emitted by small planktonic organisms during its passage.
Located in the center of the tentacles, the buccal mass, up to 11 centimeters in diameter, consists of horny jaws or parrot’s beak, which are articulated and allow the prey to be meticulously minced, because the esophagus, surrounded by the skull, is very narrow.
Finally, the copulatory organ of the males or penis, enormous, can reach 80% of the length of the mantle, and with a relatively strange functionality. During mating, which has never been observed, it introduces its sperm into the female not directly inside her, but by injecting and embedding it in the mantle or her arms, as has been observed when examining specimens stranded or caught in fishing nets.
voracious predators
These sea giants are voracious predators, and a high incidence of cannibalism has been reported . They feed on fish, crustaceans, but also cephalopods. The top of the food chain? Not entirely, because the sperm whale, its most fearsome predator, is above it. Variations in the isotopic composition of carbon (C13) in the beak or jaws of giant squid from Asturias and Namibia corroborate that Architeuthis mainly inhabits areas of high marine productivity and that it appears to have some sedentary behaviour, at least in adulthood.
Data provided by currently available records indicate that adult and subadult giant squid ascend from relatively deep areas (up to about 1,600 m) to layers between 200 and 450 m deep to eat among schools of fish, which in turn follow the daily movements of their planktonic prey, governed by sunlight.
How to admit that with modern means of observation we still know so little about the largest mollusk on the planet?
Fundamentally, because it is a solitary, elusive animal that lives at great depths.
Various teams of researchers, equipped with cutting-edge technology, have been trying for almost 20 years to obtain direct images of their environment.
In 1996, with a camera attached to the head of a sperm whale in the Azores: a failure.
Between 1997 and 1999: North American campaigns with the submarine Alvin in front of New Zealand: another failure.
In 2001 and 2002 Spanish campaigns off the Asturian coast: new failures.
In 2004, the first photos at a depth of 900 meters off the coast of Japan: finally!
In 2012: the same team, with the resources of the Discovery Channel, obtained the first video images of a giant squid in situ: victory!
The end of a myth?
Recently, for reasons still unknown, several giant squids were seen in late 2015 in a port on the west coast of Japan and thus far from their natural environment. The same thing happened in 2018, when a female with a dorsal mantle length of 123 cm and a weight of 105 kg appeared alive near a port on the Galician coast in waters 5-6 m deep. She then washed up on a nearby beach. The markings on the body (suckers and beak) clearly indicated that she had been attacked and possibly fatally injured by another, larger giant squid. From then on, the myth of the ancient monster was quite distorted. The giant squid could be part of the marine bestiary just like our friendly dolphins.
A symbol of protection of deep ecosystems
If there is an animal that symbolizes the conservation of the terrestrial environment, that is the panda bear. The dolphin is considered a symbol of the protection of surface marine ecosystems. But the deeper environment does not receive such sustained attention. Although the giant squid is not an endangered species, Spanish researchers have suggested designating it as a representative of the deep marine environments to be protected, especially deep submarine canyons, extremely rich in biodiversity. Environments still little studied by scientists due to their difficult accessibility.
The giant squid, still little known and surrounded by mysteries, remains a fascinating animal for both the general public and scientists. To this title, it can be added to consider it an emblematic animal of the knowledge and protection of these particularly rich and, for different reasons, threatened deep pelagic ecosystems.