"After months of trepidation...the most uncertain development period for newborn olms is over," cave operator Postojnska jama has said.

Scientists biggest fear had been whether the hatchlings would establish the link between the mouth and the digestive tract that allows baby dragons to feed themselves after running out of yolk.

All of the 22 olms that hatched - the first one did so 122 days ago - are alive and developing better than expected. They measure around four centimetres in length, their eyes are still distinct and visible, and they still have pigment spots.

"They use their fully developed legs to great advantage, courageously navigating their aquariums, they resemble dinosaurs when hunting and are beginning to show signs of territorial behaviour and occasionally mess with each other when prey is near."

The quick development in the larval stage is now to slow down, as experts expect their eyes will be covered by skin in the next two to three years and the pigmentation gone in about a year and a half.

The next stage in the development, the juvenile period, takes about 14 years, so they have quite some time for antics.

"They mess with each other when hunting and 'brotherly quarrels' quickly flare up... But if they seem angry and hungry one moment, they happily 'prance' in front of the camera in the very next."