Bigfin squids are a group of rarely seen

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s with a distinctive

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

. They are placed in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

''Magnapinna'' and

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Magnapinnidae. Although the family is known only from larval,

paralarva Paralarvae (singular: ''paralarva'') are young cephalopods in the planktonic stages between hatchling and subadult. This stage differs from the larval stage of animals that undergo true metamorphosis. Paralarvae have been observed only in membe ...

l, and juvenile specimens, some authorities believe adult specimens have also been seen. Several videos have been taken of animals nicknamed the "long-arm squid", which appear to have a similar morphology. Since none of the seemingly adult specimens has ever been captured or sampled, it remains uncertain if they are of the same genus or only relatives. The arms and tentacles of the squid are both extremely long and believed to be long. These appendages are held perpendicular to the body, creating "elbows." How the squid feeds is yet to be discovered.

Physical specimens

The first record of this family comes from a specimen (''

Magnapinna talismani ''Magnapinna talismani'' is a species of bigfin squid known only from a single damaged specimen. It is characterised by small white nodules present on the ventral surface of its fins. Description The holotype of ''M. talismani'' is a specimen of ...

'') caught off the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

in 1907. Due to the damaged nature of the find, little information could be discerned, and it was classified as a

mastigoteuthid The Mastigoteuthidae, also known as whip-lash squid, are a family of small deep-sea squid. Approximately 20 known species in six genera are represented, with members found in both the mesopelagic and bathypelagic zone of most oceans. Originally d ...

, first as ''Chiroteuthopsis talismani'' and later as ''Mastigoteuthis talismani''. In 1956, a similar squid ( ''Magnapinna'' sp. C) was caught in the South Atlantic, but little was thought of it at the time. The specimen was illustrated in

Alister Hardy Sir Alister Clavering Hardy (10 February 1896 – 22 May 1985) was an English marine biologist, an expert on marine ecosystems spanning organisms from zooplankton to whales. He had the artistic skill to illustrate his books with his own drawings ...

's ''The Open Sea'' (1956), where it was identified as ''Octopodoteuthopsis''. During the 1980s, two additional immature specimens were found in the Atlantic ( ''Magnapinna'' sp. A), and three more were found in the Pacific (''

Magnapinna pacifica ''Magnapinna pacifica'' is a species of bigfin squid known only from three immature specimens; two caught at a depth of less than 300 m and one from a fish stomach. ''M. pacifica'' is the type species of the genus ''Magnapinna''. It is characteri ...

''). Researchers Michael Vecchione and Richard Young were the chief investigators of the finds, and eventually linked them to the two previous specimens, erecting the family Magnapinnidae in 1998, with ''

'' as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

. Of particular interest was the very large fin size, up to 90% of the mantle length, that was responsible for the animals' common name. A single specimen of a fifth species, ''Magnapinna'' sp. B, was collected in 2006. ''Magnapinna'' sp. A was described as ''

Magnapinna atlantica ''Magnapinna atlantica'', previously known as "''Magnapinna'' sp. A", is a species of bigfin squid known from only two specimens collected in the northern Atlantic Ocean. It is characterised by several unique morphological features: the tentacle ...

'' in 2006. The genus was described from two juveniles and

, none of which had developed the characteristic long arm tips. However, they did all have large fins, and were therefore named "magna pinna", meaning "big fin".

Sightings

The first visual record of the long-arm squid was in September 1988. The crew of the

submersible A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of ind ...

'' Nautile'' encountered a long-armed squid off the coast of northern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, , at a depth of . In July 1992, the ''Nautile'' again encountered these creatures, first observing one individual two times during a dive off the coast of

Ghana Ghana (; tw, Gaana, ee, Gana), officially the Republic of Ghana, is a country in West Africa. It abuts the Gulf of Guinea and the Atlantic Ocean to the south, sharing borders with Ivory Coast in the west, Burkina Faso in the north, and To ...

at and depth, and then another one off Senegal at . Both were filmed and photographed. In November 1998, the Japanese crewed submersible ''Shinkai 6500'' filmed another long-armed squid in the Indian Ocean south of Mauritius, at and . A third video taken from the remotely operated underwater vehicle (ROV) of the oil-drilling ship ''Millennium Explorer'' in January 2000, at Mississippi Canyon in the Gulf of Mexico () at , allowed a size estimate. By comparison with the visible parts of the ROV, the squid was estimated to measure with arms fully extended. The ROV ''Atalante'' filmed another Indian Ocean specimen at and , in the area of Rodrigues Island, in May 2000. In October 2000, the crewed submersible ''DSV Alvin, Alvin'' found another long-armed squid at in Atwater Valley, Gulf of Mexico (). These videos did not receive any media attention; most were brief and fairly blurry. In May 2001, approximately ten minutes of crisp footage of a long-armed squid were acquired by R/V Western Flyer, ROV ''Tiburon'', causing a flurry of attention when released. These were taken in the Pacific Ocean north of Oʻahu, Hawaii (), at . On 11 November 2007, a new video of a long-arm squid was filmed off Perdido (oil platform), Perdido, a drilling-site owned by Shell Oil Company, located 200 statute miles (320 km) off Houston, Texas in the Gulf of Mexico. Observations of ''Magnapinna'' sp. were made in the Great Australian Bight during towed camera and remote operated vehicle surveys in 2015 and 2017 respectively. On 9 November 2021, a video of a long-armed squid was captured at a ridge feature off the Florida Platform#Structure, West Florida Escarpment by an ROV from the NOAAS Okeanos Explorer, NOAAS ''Okeanos Explorer'' as part of the Windows to the Deep 2021 expedition. The squid was found at a depth of 2,385 m (7824.8 ft), and its size is currently being measured using paired lasers. Currently, there are officially 3 known species of bigfin squid.

Anatomy

The specimens in the videos looked very distinct from all previously known squids. Uniquely among

s, the arms and tentacles were of the same length and looked identical (similar to extinct belemnites). The appendages were also held perpendicular to the body, creating the appearance of strange "elbows". Most remarkable was the length of the elastic tentacles, which has been estimated at up to 15-20 times the mantle length. This trait is caused by filament coiling of the tentacles, a trait that is rare among similar species. Estimates based on video evidence put the total length of the largest specimens at or more. Viewing close-ups of the body and head, it is apparent that the fins are extremely large, being proportionately nearly as big as those of bigfin squid larvae. While they do appear similar to the larvae, no specimens or samples of the adults have been taken, leaving their exact identity unknown. While their exact identity is unknown, all of the discovered specimens can be observed to have a brown-orange color body, translucent fins, near-white tentacles, and dark eyes. These species of squids are mainly identifiable by their long thin arms and specific colors.

Feeding-behaviour

Little is known about the feeding-behaviour of these squid. Scientists have speculated that bigfin squid feed by dragging their arms and tentacles along the seafloor and grabbing edible organisms from the floor. Alternatively, they may simply use a trapping technique, waiting passively for prey such as zooplankton, to bump into their arms (see Cephalopod intelligence). The diet of the bigfin squid is unknown. However, cephalopods are known to feed on crustaceans, jellyfish, and even other cephalopods.

References

External links