Sasaki, 1929
Description
Adult. Body dorso-ventrally flattened. Mantle elongated oval and much larger than head; mantle length up to 20 cm; mantle width is about 30 % of its length.
Anterior dorsal edge of mantle with a tongue-like projection. A large gland whose duct opens between the fins in form of a red spot lies under skin in postero-dorsal part of mantle. A row of several large brightly coloured spots extends along the fin base.
Fins are narrow, extending from anterior to posterior edge of mantle. Arms with 2-4 rows of suckers. The fourth arm is considerably broader than the others, with a muscular swimming membrane.
Tentacles are retractile. Club suckers in 16-32 rows (usually more than 20 rows). Sepion (shell) is narrow and tongue-like, without spine. Undersurface of sepion is concave in posterior half and, together with lateral edges of shell, forming a "fork" (inner cone). The internal shell is bordered by a lateral ridge that is wide in posterior half and narrow in anterior half of sepion. Ink sac is well developed.
Juvenile. Description not available. Hatchlings come out as miniature adults (see Lu et al., in Sweeney et al., 1992, p. 21.). The identification characters for juveniles are hence similar to those that are used for the identification of adults.
Size
Maximum mantle length 20 cm.
Depth range
Bentho-pelagic, inhabiting continental shelf, sometimes reaching upper bathyal zone.
Distribution in the North Sea
Exotic species occasionally found in the North Sea.
World distribution
W Pacific: Japan, China, Philippine Islands.