The men preyed on the families of youngsters to gain access to them and, in one case, groomed a mother and father before their baby was born.
Members travelled hundreds of miles to carry out sickening attacks together or used internet streaming to provide real-time encouragement and directions to those abusing victims.
The seven - aged between 31 and 51 and including three convicted sex offenders - were convicted of 29 child sex abuse offences, including conspiracy to rape and the multiple rape of a child aged under 13.
They are David Harsley, 51, from East Yorkshire, John Denham, 50, from Wiltshire, Matthew Stansfield, 35, from Hampshire, Adam Toms, 33, from Somerset, Christopher Knight, 35, from Manchester, Robin Hollyson, 31, from Bedfordshire, and Matthew Lisk, 33, from Sussex.
Passing sentence at Bristol Crown Court, Judge Julian Lambert said: “In the worst nightmare, from the very deepest recesses of the mind, at the darkest hour of the night, few can have imagined the terrifying depravity which you men admit.
“What you contemplated and what you did involved the most horrific abuse of a baby and very young children.
“Your thoughts and deeds are beyond human instinct and reason, and are evil beyond rational understanding.
“You men indulged yourselves in some of the most depraved and grossly deviant behaviour imaginable. The depth to which you sank is astounding and highly shocking to all decent people.
“What you did is contrary to all nature and humanity and you each appear to have a chilling tendency to centre the world on yourselves and your depraved desires without regard for the innocent and vulnerable.
“Your conduct is of deep concern to the public and people are outraged at what you have done. What you did provokes tears in many and makes others feel physically sick.
“Given the strength of public feeling I consider that retribution has a very large part to play in the sentencing exercise. This is no case for treatment and rehabilitation outside prison.”
The judge continued: “You each made choices. Those choices have proved catastrophic for you personally but that is of slight concern when compared with the devastating impact of your actions on the victims and their families.
“The material you viewed and the urges you excited in each other were matters of choice for you. You sought out the darkest materials on the internet and met in cyberspace to discuss your perverted sexual desires.
“You then planned the most shockingly sordid exploitation of the very young for sexual purposes. Targeting innocent children in that way is utterly abhorrent and is bound to receive condign punishment.
“The degraded and deplorable state into which you have rendered yourselves is pitiful but there is no room for mercy here.
“All sympathy and compassion must be extended to the victims of crime and their families, and not you.”
Hollyson received a 24-year prison sentence plus an extension of eight years on licence while Toms was jailed for 12 years plus an extension of four years on licence.
Knight was jailed for 18 years plus an extension of six years on licence and Stansfield received a 10-year prison sentence plus an extension of four years on licence.
Denham was jailed for eight years plus an extension of four years on licence.
Lisk was jailed for four years plus an extension of three years on licence and Harsley was jailed for two years
They were all placed on the sex offenders’ register for life, except for Harsley whose length is still to be determined by the judge.