Several sightings of mysterious giant-finned squid documented in the Great Australian Bight

Observation 3: ROV images of a Magnapinna squid at a depth of 3060 m. (A) Close-up view of Magnapinna squid encountered 5.3m above the seabed with slightly open proximal arms / tentacles and slowly waving fins. (B) Full extent of arms / tentacles, longest measuring approximately 1680mm. Credit: PLOS ONE (2020). DOI: 10.1371 / journal.pone.0241066

A team of researchers from CSIRO Energy, the Commonwealth Scientific and Industrial Research Organization, and the Victoria Museums have documented several sightings of bigfin squid in the depths of the Great Australian Bight. In their article published in PLOS ONE, the group describes their study of unique creatures and what they learned about them.

The Bigfin squid lives deep in the ocean and is remarkable for several reasons. The first is that they are rarely seen in the wild – researchers have only documented 12 sightings. They also have unique fins that protrude from the side of the head at an angle that resembles Dumbo’s ears – and they serve the same purpose, albeit in water instead of air. They also have long tentacles that are several times longer than their body. And they live thousands of feet deep in the ocean.

Due to their remoteness, little is known about the bigfin squid outside of its general physical attributes. This sighting is the first in the Great Australian Bight (the huge open bay on the south coast of the country). In addition, this is the first time that the squid has been observed in a group of sorts. Although hundreds of meters apart, they apparently shared parts of the ocean. Squids are generally loners.

Another first was to laser measure a specimen: a bigfin squid with a body (mantle) 15 centimeters long. More impressive were its tentacles, measured at 1.8 meters. All previous measurements of the bigfin squid had been estimates based on baseline information such as other fish nearby.

Researchers found the squid while conducting underwater surveys in the bay. When they came across the first specimen, they deployed other tools to get a better view. They used both remotely operated underwater vehicles and towed cameras. In all, they carried out more than 40 hours of underwater observations at depths ranging from 950 to 2,400 meters below the surface – and ended up filming five of the rare squids.

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