Opisthoteuthis carnarvonensis
- 演化之聲
- Mar 12
- 3 min read
Updated: Apr 10
Taxonomy
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Octopoda
Family: Opisthoteuthidae
Genus: Opisthoteuthis
Species: Opisthoteuthis carnarvonensis
Morphological description
Carnarvon flapjack octopus (Opisthoteuthis carnarvonensis) is a flattened, gelatinous deep-sea member of the family Opisthoteuthidae. The mantle is short and dome-shaped, measuring approximately 3.3–4 cm in length, with a rounded posterior margin. The head is relatively large and distinctly wider than the mantle. The fins are positioned near the posterior end of the mantle and are comparatively small, with a nearly straight posterior margin, a gently curved anterior edge, and rounded tips.
The eyes are exceptionally large, reaching roughly two-thirds of the head width. The eye opening is narrow and constricted, an adaptation consistent with low-light deep-sea environments. The siphon (or funnel) is relatively elongate and conical. The mantle aperture is narrow and closely surrounds the funnel. Olfactory papillae are small and oval in shape.
The gills are pale orange and typically bear seven primary gill lamellae on each side, though eight may occur in some individuals. The arms are thick and relatively long, with all arms roughly similar in length. Adult individuals possess approximately 70–78 suckers per arm. The suckers display strong sexual dimorphism: males possess specialized enlarged sucker fields on both the proximal and distal portions of the arms, forming swollen sucker clusters, whereas females lack these specialized regions.
The dorsal surface of the body ranges from orange-brown to reddish-brown in life and darkens to brown or maroon after preservation. The head and arms bear areolar spots consisting of pale circular patches surrounded by darker pigment rings. These markings extend from the arm bases toward the arms and the central region of the head. The oral surface is dark reddish-orange, while the suckers and cirri are noticeably paler, producing a strong colour contrast.
Etymology
Genus name Opisthoteuthis: The prefix opistho- (ὀπίσθιος) means "posterior" or "located behind," and -teuthis (τεῦθις) refers to cephalopods such as squid or octopus. Together the name refers to a cephalopod possessing distinctive posterior structures.
Species name carnarvonensis: The species epithet refers to the Carnarvon Canyon Marine Park, the region where the species was discovered. The Latin suffix -ensis denotes origin or association with a particular place.
Biological description
Carnarvon flapjack octopus is a benthic deep-sea species currently known only from the outer continental shelf and submarine canyon systems off northwestern Australia. Recorded localities include the waters near North West Cape and the Carnarvon Canyon region. Specimens have been collected at depths between approximately 1,044 and 1,510 metres. Compared with other species of Opisthoteuthis from Australia and the Indian Ocean, its known distribution appears relatively restricted and may represent a regionally differentiated deep-sea lineage, although additional sampling will be required to determine its full range.
Based on both morphology and habitat depth, the species is inferred to follow a low-energy lifestyle typical of deep-sea cirrate octopods. Its flattened mantle, extensive webbing between the arms, and terminal fins likely facilitate slow gliding or gentle fin-assisted locomotion through the water column rather than rapid swimming. The exceptionally large eyes suggest that the animal relies on faint ambient light or bioluminescent signals for environmental perception.
In terms of reproductive morphology, males possess enlarged sucker fields at both proximal and distal arm regions. These structures are presumed to assist in grasping the female or stabilizing the pair during mating. Females possess a large ovary and an elongated oviduct. Some examined specimens contain developing oocytes, indicating a reproductive strategy involving gradual maturation and potentially multiple spawning events.
Morphologically, O. carnarvonensis resembles Opisthoteuthis kerberos from southeastern Australia and Opisthoteuthis chathamensis from New Zealand and Macquarie Island in general body proportions and digestive gland structure. However, the Carnarvon species can be distinguished by several features, including the presence of web nodules and a greater number of arm suckers, indicating a distinct evolutionary lineage within the genus.
（Author: Shui-Ye You）
Reference
Verhoeff TJ. (2025). Flapjack octopods of Australia (Cephalopoda: Cirrata: Opisthoteuthidae), Part II northwestern Australia and adjacent waters. Australian Journal of Taxonomy.
（Paid content. Unauthorized reproduction or use is prohibited.）
Comments