About Sepiadarium austrinum S.S.Berry, 1921
Sepiadarium austrinum is a very small, round species with kidney-shaped fins located on the back third of its body. Its mantle can reach up to three centimeters in length, and its total maximum body length is four centimeters. Its body can be transparent, yellow, or orange, and has egg-shaped white leucophores. This species has ten arms and tentacles, with nine or ten rows of suckers on each arm.
Sepiadarium austrinum is distributed in the southern Indo-Pacific region, specifically in southern Australia, with a small population occurring in the Spencer Gulf. It mostly inhabits sandy areas in shallow, sheltered waters at depths up to 65 meters.
Sepiadarium austrinum begins reproducing at a young age, and even immature females are capable of storing sperm. Individuals mate with multiple partners. Mating is initiated by males, and no courtship behavior has been observed. Males transfer sperm packages to females, which store the sperm in a pouch located below their mouth. Males can use a specialized arm to remove sperm from other males out of this pouch. Females can also remove sperm from the pouch, and regularly consume spermatophores. Females fertilize eggs by passing them over the sperm storage pouch. Clumps of eggs are covered in sand and attached to seaweed or seagrass.
Sepiadarium austrinum is an annual species, and juveniles settle quickly after hatching.
