Police have charged a 26-year-old man following a search for a platypus allegedly removed from its habitat north of Brisbane earlier this week.
They allege the man took the animal from a local waterway then travelled by train to Caboolture with a woman.
Police said the pair were spotted boarding a Caboolture bound train at Morayfield Station on Tuesday morning with the mammal wrapped in a towel.
He was charged with one count each of taking protected animal and restriction on keeping or using taken protected animal.
Both are class one offences and can attract a fine of up to $430,000.
Police said they had "been advised" the animal was released into the Caboolture River, but it has not been located and its condition is unknown.
The Department of Environment and Science said the longer a platypus is out of the wild, the higher the chance it could become sick or die.
The department said in Queensland, platypuses live in rivers east of the Great Dividing Range, and are also found in some western-flowing streams.
Police have also interviewed the woman and the investigation is ongoing.
The man is due to appear in the Caboolture Magistrates Court on Saturday.
