Colossal squid filmed in natural habitat for first time - PHOTO

Measuring just 30cm long, the juvenile squid was spotted at a depth of 600m (1,968ft) near the South Sandwich Islands in the South Atlantic Ocean.

Experts believe colossal squid eventually grow up to 7m (23ft) in length - and can weigh up to 500kg (1,100lbs).

That's equivalent to a Fiat 500 car, making it the heaviest invertebrate on the planet.

The footage was captured by crew on board the Schmidt Ocean Institute's Falkor (too) vessel, with a remotely operated vehicle called SuBastian filming the video.

Experts from the University of Plymouth and the British Antarctic Survey were among those involved in the 35-day quest.

Dr Kat Bolstad, who helped verify the footage, says that - until now - colossal squid had mainly been encountered as prey remains in whale and seabird stomachs.

"It's exciting to see the first in situ footage of a juvenile colossal and humbling to think that they have no idea that humans exist," she added.

The colossal squid remains shrouded in mystery - and while little is known about their lifecycle, adults eventually lose the see-through appearance of juveniles.

Another distinguishing characteristic of this species - formally known as Mesonychoteuthis hamiltoni - is the presence of hooks on the middle of their eight arms.

Scientists revealed that, in January, they also managed to film confirmed footage of the glacial glass squid for the first time ever.

"The first sighting of two different squids on back-to-back expeditions is remarkable and shows how little we have seen of the magnificent inhabitants of the Southern Ocean," the Schmidt Ocean Institute's executive director Dr Jyotika Virmani added.

"These unforgettable moments continue to remind us that the ocean is brimming with mysteries yet to be solved."