Adam Britton, 51, began his offending in 2014 and sexually exploited more than 42 dogs until his arrest in April 2022.
Britton stood calmly as he pleaded guilty to animal cruelty in the Northern Territory Supreme Court on Monday.
He also pleaded guilty to four counts of accessing and transmitting child abuse material.
The horrific abuse resulted in the deaths of 39 dogs.
Before prosecutor Marty Aust read out the agreed facts of the charges, chief justice Michael Grant urged the public gallery, security staff and media to leave the court.
“These facts contain material that can only be described as grotesque and perverse acts of cruelty which is confronting and distressing and which in my assessment have the potential to cause nervous shock,” he said.
“Either way I’ll leave that up to you, but the potential has been described.”
As well as torturing his own dogs, Britton sourced other canines via Gumtree Australia from unsuspecting owners in the Darwin region.
“[He] often built a rapport with the dog owners in negotiating taking custody of their animals, many of whom had to reluctantly give their pets away due to travel or work commitments,” Aust said.
The former academic, who once hosted legendary broadcaster and biologist David Attenborough, was born in the UK and completed his PhD in zoology at the University of Bristol.
Britton would share videos and images of himself sexually exploiting the dogs on online forums under pseudonyms.
A video was eventually sent to the NT Animal Welfare Branch and passed on to NT police, who arrested Britton in April 2022.
He has been remanded in custody since then.
Britton was a prominent NT crocodile expert and a senior researcher at Charles Darwin University.
None of his offending is alleged to have been against the reptiles.
His matter is set to return to court on 13 December for sentencing submissions.