The Dusky Antechinus is a small ground-dwelling marsupial, about the size of a small rat. Its colour varies from dark grey to almost black.
Restricted generally to damper environments than A. agilis (Brown Antechinus) it has a patchier distribution, although in some areas they occur together.
The most dense populations occur in mountainous areas, where the preferred habitat is alpine heath or tall open forest with a dense understorey of ferns or shrubs.
For such a small animal it is an incredibly voracious carnivore, fossicking in rich topsoil with its sharp claws for insects, spiders and worms and is known to feed on small vertebrates such as reptiles. Bogong moths are a favourite food in summer.
The Dusky Antechinus is mainly nocturnal. In winter, females build a nest of grass and leaves in cavities of logs and stumps or in burrows where they raise their young.
Individuals are usually solitary except for the brief mating period and when the female is raising young. The breeding cycle of this animal is remarkable. Mating occurs for a short period between July and September, depending on altitude. Vigorous competition occurs between the males for females and the frenzied mating period ends within three weeks after which most males die.
This is largely due to extreme stress levels associated with physiological changes brought on by the breeding period.
Following a gestation period of about 28 days the young move into the mother's pouch and become attached to a nipple. There are usually eight nipples, except in the Otways where individuals have six nipples.
After about 60 days in the pouch, they are left in the nest and the mother forages. Young may be carried on the mother's back or left in a den while the mother hunts, until independent at about 13 weeks.