Fig 1.
Observations of Magnapinna sp. in the Great Australian Bight.
Observations of Magnapinna sp. (yellow circles) with sighting numbers, and the locations visually surveyed by towed camera (pink triangles) and Remotely Operated Vehicles (blue squares) in the Great Australian Bight (GAB). Bathymetric contours are 100, 200, 400, 1000, 1500, 2000, 3000 and 5000 m. Inset shows the location of the study area in the GAB.
Table 1.
Details of Magnapinna sp. observations in the Great Australian Bight.
Table 2.
Morphology measurements of Magnapinna sp. observed in the Great Australian Bight.
Fig 2.
Sighting 1: Towed camera images of a Magnapinna squid at a depth of 2178 m.
(A) A still image captured by towed camera. A Magnapinna squid was observed in the shadow of the towed camera system, just above the substrate with distal arm/tentacle filaments largely trailing parallel to the seafloor. Coiling of distal arm/tentacle filaments can be seen at their proximal ends. Image light levels have been adjusted for clarity, and distance between paired lasers seen on the seafloor is 100 mm. (B) A video image captured by towed camera. The squid is seen with proximal arms/tentacles spread, swimming upwards with undulating fins to a vertical position less than 100 mm from the seafloor. Colour is described from this image.
Fig 3.
Sighting 2: Towed camera image of a Magnapinna squid at a depth of 2110.
A small Magnapinna squid (62 mm DML) was seen in a horizontal position, parallel to and just above the seafloor. Its proximal arms/tentacles were spread outwards at an almost 90 degree angle to the body axis (causing the mantle and proximal arms/tentacles to appear as a cross-like shape in the image), and its distal arm/tentacle filaments streamed posteriorly, perpendicular to the proximal arms/tentacles and parallel to the seafloor (seen here as fine lines running diagonally from the squid to the bottom right of the image). The shadow of the Magnapinna squid can be seen below, duplicating the described posture. This image is an enlarged and cropped portion of a towed camera still image and light levels have been adjusted for clarity.
Fig 4.
Sighting 3: ROV images of a Magnapinna squid at a depth of 3060 m.
(A) Close view of the Magnapinna squid encountered 5.3 m above the seafloor with proximal arms/tentacles seen slightly opened and fins undulating slowly. (B) Full extent of arms/tentacles, the longest being approximately 1680 mm.
Fig 5.
Magnapinna squid displaying raised arm behaviour.
Magnapinna squid from (A) Sighting 3 and (B) Sighting 4 exhibited a postural behaviour, in which a single arm/tentacle (without filament) was raised perpendicular to the anterior-posterior body axis while the squid moved upwards and into a horizontal posture.
Fig 6.
Sighting 4: ROV images of a Magnapinna squid at a depth of 3002 m.
(A) Lateral view of Magnapinna squid encountered at a depth of 3002 m. (B) The Magnapinna squid swimming horizontally with rapid fin flapping in water affected by ROV thruster turbulence. The squid was missing three distal arm/tentacle filaments.
Fig 7.
Sighting 5: ROV images of a Magnapinna squid at a depth of 3056 m.
The Magnapinna squid was greatly affected by turbulence from ROV thrusters during this brief observation. Several colour descriptions were necessary for this squid. (A) Ventral view of the Magnapinna squid showing pale mantle and proximal arms/tentacles. (B) Dorsal view showing dark orange-brown mantle and proximal arms/tentacles. (C) Dorsal view showing a pale pink-brown mantle and light brown proximal arms/tentacles. (D) Lateral view showing a pale mantle and dark orange-brown proximal arms/tentacles.