Despite coming in at around 13 meters long (42 feet long) and weighing hundreds of kilograms, little is known about the giant squid. Fewer than a thousand specimens have ever been found, and most of these were dead individuals.
Of those squid that have been found stranded live in coastal waters, almost all have come from around Japan, apart from a single individual that in 2016 washed up on the northwest coast of Spain. This is the first report of a live stranded giant squid from outside Japanese waters. The discovery is published in the journal Ecology.
The event took place on October 7, 2016, on Bares beach at the northernmost point of Spain. It was spotted not far from the wharf, floating around 3 meters (10 feet) underwater. It was still alive and kicking for a couple of hours before it washed ashore. On inspection, researchers were able to ascertain that it was an immature female that weighed in at 105 kilograms (230 pounds).
Curiously, the specimen was covered in cuts and scrapes not consistent with being beached. A further examination of the young female’s mantle showed that the likely attacker was not a predator but another massive squid, with the size and shape of the sucker marks consistent with that of its own species. The researchers now think that the unfortunate adolescent was caught in a leggy battle with another giant squid, most likely competing for food.
They think that the giant squid were brought to this region of the Spanish coast as they hunt for a fish known as the blue whiting. These fish form massive shoals between 150 and 3,000 meters (480 and 9,800 feet) down, although they are more common at between 300 and 400 meters (980 and 1,312 feet). Due to the density of the shoals, the fish are not only of value to the giant squid but to trawlers as well.
While the hunting behavior of the giant squid is not yet fully understood, it's likely either actively pursuing prey or lying in ambush, with one report noting that the cephalopods sat below the shoal and flicked their tentacles up to snare the fish. The massive shoals of blue whiting likely attract many giant squid, and the researchers suspect that this encourages kleptoparasitism, in which larger squid attack and steal fish from smaller ones.
The wounds on the live specimen point towards this as a possible cause of death. After being attacked by another squid, it may have been disorientated and swum into warmer waters, where its blood efficiency dropped and it effectively asphyxiated.