Bigfin Squid

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Bigfin squid are a group of cephalopods in the genus Magnapinna and family Magnapinnidae. Little is known about the big fin squid as no adult specimens have ever been captured or sampled. Nonetheless, these animals are notable for their arms and tentacles that are extremely long and thought to be 4 to 8 m (13 to 26 ft) in length.

Currently, scientists have officially described three species of these giant squid, but there may be more. Only more sightings of these unique animals will help us to understand them more.

Bigfin Squid Characteristics

Bigfin squid stand out from other squid because of their extremely long arms and tentacles. These have been estimated at up to 15-20 times the mantle length, making some of the largest specimens at 8 metres (26 ft) or more. What’s more, the appendages also seem to be held perpendicular to the body, creating the appearance of strange “elbows”

Like other squid, bigfin squid have eight arms and two tentacles — each covered with microscopic, sticky suckers. But the arms and tentacles are indistinguishable from each other, unlike other squid. Also, it is thought that the appendages have little muscle, and likely rely on water movement to maintain their characteristic pose.

Bigfin Squid Diet

Very little is known about the diet or the feeding behavior of these deep-sea squid. It is thought by scientists that they feed by dragging their arms and tentacles along the seafloor and grabbing edible organisms from the floor. They may also use a trapping technique, and trap zooplankton as and when it swims past or bumps into their arms.

Use of Arms and Tentacles

Scientists believe that Bigfin Squid use their long arms and tentacles to trap prey. These appendages have microscopic suckers on them. The squid might hang them down in the water below their body or drag them along the seafloor to catch any prey that bumps into them.

The ‘elbows’ of Bigfin Squids are a unique feature among cephalopods. These are not actual joints but an effect of the squid holding its arms and tentacles in a perpendicular orientation to its body.

Bigfin Squid Location and Habitat

Bigfin squid are widely distributed throughout the world’s deep ocean, and they can live deeper than any other known squid. They live at extreme depths and the current depth record for a Bigfin Squid is an impressive 4,735 meters (about 3 miles)!.

They have been spotted off the coast of Ghana, Senegal, south of Mauritius, the Gulf of Mexico, Hawaii, in the area of Rodrigues Island, the Pacific Ocean, the Indian Ocean, and even around Australia.

Sightings and Discoveries

Bigfin Squids are quite elusive and rare. There have been only about a dozen confirmed sightings worldwide. Each sighting provides valuable information that helps scientists understand more about these mysterious creatures.

Ecological Role

The ecological role of Bigfin Squid is not well understood due to the lack of quality data. However, as predators, they likely play a role in controlling the populations of their prey species.

Check out more animals that begin with the letter B

Sources & References

• Animal Diversity Web — Sepioteuthis lessoniana
• Wikipedia — Sepioteuthis lessoniana

Joanne Spencer (2026, April 8). Bigfin Squid. Animal Corner. Retrieved 2026, May 3, from https://animalcorner.org/animals/bigfin-squid/

Joanne Spencer. "Bigfin Squid." Animal Corner, 2026, April 8, https://animalcorner.org/animals/bigfin-squid/.