A bigfin squid looks jointed because the thick bases of its limbs extend outward and then meet extraordinarily thin filaments at sharp bends. The corners resemble elbows, but there are no arm bones meeting at a hinge. What the posture accomplishes is a separate question: a feeding function is plausible, while a complete meal-catching sequence remains missing.
Magnapinna is the genus behind that silhouette. The thumbnail is explanatory artwork, not a photograph of a feeding event. Its “fishing lines” label names a hypothesis rather than a demonstrated technique.
Follow a limb past the corner
The animal has eight arms and two tentacles. In familiar squid, the distinction between those groups is conspicuous. In Magnapinna, all ten carry long distal filaments, making the overall arrangement look unusually uniform. MBARI’s species account describes tiny suckers on these adhesive extensions and lists the diet as unknown.
Imagine tracing one limb with a finger on a paused video. First comes a relatively substantial section extending away from the head. Then the line changes direction and continues as a much finer strand. Repeating this around the animal creates the characteristic elbow pose. The useful observation is the relationship between those sections, rather than an assumption that the bend must contain a human-like joint.
MBARI also notes that no adult specimen has been collected. Damaged juveniles and footage of living animals provide different kinds of evidence. A broken specimen may reveal tissue while losing the delicate extensions; a video preserves posture while hiding the internal anatomy.
Muscle can provide its own support
William Kier’s 1982 study of squid arm and tentacle musculature examined loliginid squid, a different family. Their appendages lack hardened skeletal elements and consist largely of muscle. The study proposed that this muscle supplies both movement and structural support.
Longitudinal muscle can shorten one side of an arm while transverse muscle resists compression. Coordinated forces bend the appendage; differently oriented fibers can also contribute to twisting. This arrangement helps explain why a squid can make a sharp bend without a rigid elbow.
The species distinction matters. That study establishes a mechanical comparison, not a dissection of an adult bigfin squid’s particular corner. It would be too strong to turn a general account of squid movement into a complete explanation of how Magnapinna holds every part of its pose. We can explain bending without bones while leaving the precise control of these filaments open.
A very long squid need not have a very large body
NOAA’s 2021 bigfin feature describes a maximum known total length of 6.4 meters, of which 6.1 meters was arms and tentacles. Most of that impressive dimension is reach. It should not be pictured as six meters of bulky mantle followed by additional limbs.
A much smaller animal appeared in MBARI’s September 2026 encounter report. The remotely operated vehicle Doc Ricketts encountered it near Davidson Seamount at about 3,277 meters depth. Vehicle lasers helped estimate a total length of roughly 1.25 meters.
MBARI called this the first confirmed live observation in the Northeastern Pacific, not the discovery of the genus. Its team had previously encountered one off Hawaii in 2001. Keep the geographic qualifier: a first observation in one region does not erase earlier records elsewhere.
Length estimates also need a named reference point. Total length, mantle length, and the length of an individual filament describe different things. Comparing them as if they were interchangeable can make two reports appear contradictory when they are measuring different parts.
The fishing explanation needs a meal
Long adhesive strands offer a reasonable starting point for a feeding hypothesis. If small animals become attached when they touch a filament, keeping several strands spread apart could enlarge the zone in which contact occurs. This is an interpretation of the geometry, consistent with MBARI’s cautious suggestion that the filaments may fish for food.
It does not follow that the squid operates a net. There is no mesh connecting the strands. A passing animal could move between them without touching anything. Nor does attachment alone explain how food reaches the mouth.
To test the feeding idea, follow one animal through the whole proposed route:
- It contacts a filament.
- It remains attached rather than escaping.
- The squid retrieves it.
- It reaches the mouth and is ingested.
A still of the elbow pose does not establish those events. The decisive footage might show a much less dramatic subject: one small animal remaining visible throughout that sequence.
Our Bathydevius feeding article makes a similar distinction between a structure that can contain prey and the behavior that gets prey into it.
Water movement changes what the camera sees
A 2020 Great Australian Bight study documented five sightings, including a horizontal elbow pose and coiling filaments. The recognizable arrangement therefore does not require every strand to hang vertically toward the bottom.
The researchers also described substantial disturbance from ROV thrusters. Some filaments streamed passively in the moving water, and the authors suggested that the distal extensions may be poorly muscularized. This places a limit on interpretation: a swirl beside a research vehicle may reflect the observer’s turbulence rather than a hunting maneuver.
A sighting count is not a population count
An August 2026 global study assembled 46 in-water sightings from scientific publications and other reporting formats, alongside separate specimen records. The sightings extended across several ocean basins. Many came from online repositories and other sources outside traditional papers.
Those numbers describe a collected dataset. They do not tell us how many bigfin squid live outside camera range, or how many meals an individual catches. Camera placement, industrial activity, and the survival of old footage all affect which observations reach a researcher.
The elbows remain a strong identification clue. Their feeding role will become clearer when an observation connects the shape to a result, rather than leaving us to infer a way of life from an extraordinary outline.
