A new egg was spotted in the aquarium. In the last three days, the female olm relocated its egg-laying territory under a flat rock – one of the two ideal spots.

The female has laid egg number 52. The camera allowed us to watch cave amphipods (the small crustaceans we use to feed the olms) getting nearer to individual eggs. While the female was away, we could see three of them trying to bite through the egg envelope. As soon as the female returned, she immediately noticed them and attacked them.

Discovery Channel visited Postojna Cave to produce a feature about this one-of-a-kind event taking place in Postojna Cave.
The precious eggs have received extensive coverage by a number of media outlets across the globe. But no other camera is allowed near the eggs, except the infrared cameras recording their development in complete darkness. 

The female suddenly left the eggs and moved to the other end of the aquarium, where she laid another egg. The biologists are speculating that this might be the olms' natural behaviour: placing eggs in different spots gives them a greater chance of survival.

The olms were seen making S-shaped movements, which made for a proper little dance performance and a source of entertainment for the cave visitors who were watching it on the screen inside the cave.

The gills of our embryos are slowly branching. The blood circulation and the first heartbeat are noticeable. Life is becoming more and more tangible. The embryos have become considerably calmer.

We received another visit by Dr Mali and Dr Sessions. Dr Mali took a photograph of an embryo under the microscope.
She pointed out that a small dimple for the toes is already visible on the limb rudiment, which is a sign that it is not long until the hatching stage. (We have to admit that we were happy like proud expecting parents seeing their baby's ultrasound.)
The embryo seems to be in the development stage 19 according to Briegleb.

The gills are more branched, the eye pigment is visible, the heart is beating and is supplied with blood. The size of the embryo is between 17 and 18 mm.

Only one day after the first baby dragon, its younger sibling was caught in the act during hatching. Another moment of new life being born was captured.

Another olm hatchling has made its way out of the egg. If this makes you think ‘so what’s new’, think again. This particular hatchling is obviously being very cautious, knowing that it is not good to be reckless and hasty. Therefore, it started breaking through the egg envelope with its tail, and hatched differently than what happens usually, i.e. with its tail first and only then – after it had made sure everything was fine – the head followed as well. 

What do you call someone who survived even though most of the people had believed (s)he would not make it? Someone who, statistically speaking, was least likely to make it because his/her living conditions were simply too harsh. Someone who surprised and impressed all others with his/her birth, perseverance and persistence. The perfect name seems to be... Boris!

Boris hatched from an egg that was closest to the infected – mouldy – eggs, so we had to move him to a special container, which had no special filtration and the water was filtered in a ‘natural’ way. In the meantime, we waited and waited. And on day 142, Boris finally made it and posed in front of the camera somewhat cheekily. Welcome, Boris, you wild little thing, we wish you good luck. 

As with any child, there comes a time for some measurements and numbers. When it comes to olm hatchlings, this needs to be done without touching, so a grid sized 1 x 1 cm has been placed at the bottom of the aquarium. The largest ‘dragons’, which hatched first, are now between 2 and 2.5 centimetres long. In some of the hatchlings, yolk is still visible in the abdominal area and some already have all three digits on their front feet.

Our two biologists once again rolled up their sleeves and made their way to one of the few perfectly clean parts of the River Pivka to get some mud, which they then put into a special Petri dish and placed it in the container with one of the olm hatchlings. We wanted to check how the hatchling would react to elements from the natural environment. The baby dragon was happy to plunge into the mud and also made good use of the Petri dish itself, hiding under it. As olms like being right next to stones because this makes them feel safe, we set up some hiding places made of glass for others as well, where they are now resting happily. 

The baby dragons are hungry. Five days ago, we treated the four oldest and largest ones to a proper feast – some delicious worms. Two of the hatchlings were happy to eat them. Although almost all olm hatchlings still have some yolk reserves left, the fact that they are already eating means they are developing just the way they are supposed to. In the days after, we fed the worms to the other hatchlings as well and we are happy to report that some of them munched their way through the prey like fearsome dragons. 

The baby dragons are losing weight – as far as development goes, this is perfectly normal, as our hatchlings are growing in length; in fact, some of them are now even more than three centimetres long. The legs of the most developed ones are already functional, i.e. the baby olms have ten digits, four legs and are busy exploring their surroundings as we speak. When hunting for worms they are making use of their rear legs – they are using them to move around. The most advanced baby olm explorers resemble the dragon momma more and more every day and are growing very fast. Dear baby dragons, you’re welcome to overtake in the left-hand lane, but do it with caution and with best of luck. 

This is the sound of our baby dragons carefully and slowly moving towards prey. Their hunting instinct is very much alive and kicking. Their eyes are clearly visible, the pigment is still present, but the yolk is all gone, as they now make sure they are not hungry themselves. The biggest baby dragons are between 4.5 and 5 cm long. As far as their looks are concerned, they are now already very much alike adult olms. 

While our adult olms are feasting on fresh amphipods, the baby dragons enjoy spending time in their hidden kingdom. We are still seeing to their food, and making sure they have their favourite "furniture" at hand – rocks, which they can hide behind. All of the baby dragons are now 5 cm or more in length. May they be growing just as fast as they have so far.

Two olm babies made sure there was a bit of a panic. We noticed the two oldest olm hatchlings had white spots on their heads. Without having a closer look at it, we were not sure what it was, so naturally we got worried something was wrong. Therefore, the whole team got together and made their way into the cave with a lump in their throat instead of going home to do some Friday afternoon 'couch potatoing’. Dr Mali and Dr Sessions made it from Ljubljana during a blizzard as well. "They are growing up," was our team's official diagnosis. The white dots obviously signify a loss of pigment, which we had said would happen. In about a year, "white spots" will cover their entire bodies and the hatchlings will change "colour" and thus become even more similar to their parents; in fact, during adolescence, pigmentation gradually decreases, until it has completely disappeared. Beautiful, but somewhat painful at the same time. They will grow into proper big dragons almost too quickly.

Over a year ago, on 30 January 2016, the daily work of the three-member Postojna Cave laboratory team changed completely and ever since then their workdays kick off in a totally different way. For more than a year now, the team leader and head of the underground laboratory, Katja Dolenc Batagelj, has been starting off her working day by observing the baby dragons in the laboratory, while our two resident biologists make sure the young olms get all the living food they need. Even now, more than a year later, the team members visit the laboratory every single day, keeping an eye on the development of 21 olm juveniles, providing them with the food (every three days), changing the water and making sure the olms have the optimum living conditions. According to experts, the Postojna Cave laboratory is a remarkable success that is setting new paradigms; in fact, owing to a high number of olm survivors it is currently considered the most successful cave laboratory in the world. Here's to a lot of success and luck in taking care of the baby dragons in the future!

Measuring, observing and taking photos... The year-old baby dragons have been visited by a complete team of experts in order to assess how well they were doing: they are healthy, they have a healthy appetite and they are making good progress. At the moment, they are between 7.5 and 8 centimetres in length, which means they have grown 5-6 centimetres in a year. Their skin is still slightly pigmented, but their tiny pigmented eyes, which is the visual feature that distinguishes them from adult olms most, will slowly "disappear". Their eye diameter currently measures 0.5 millimetres, but since the cornea is already slightly thickened, it is no longer so translucent. As soon as their eyes are completely covered with skin, our baby dragons will become real adult dragons. :)

We have witnessed how wild young olms can be. They are often territorial and get into fights, which is perfectly normal behaviour at this age. We noticed that after a tussle between two juvenile olms in one of the aquariums, one of our ‘baby dragons’ ended up without his left hind leg! His brother, with whom he had been sharing the aquarium until this unfortunate event, injured him badly by biting his leg. We took care of the olm and then let nature run its course, which showed how amazing mother nature really is when it comes to our baby olms. The injured olm's leg first fell off, however, a new one started growing soon after. We named the injured olm Victor.

Victor is proudly showing off his new leg! A mere year and a half after a violent tussle between two young olms, the wounded ‘baby dragon’, Victor, has grown a new leg. We have kept a close eye on the olm’s remarkable ability to regrow limbs and have documented it all on a regular basis. The development of a new leg from a set of cells to a fully functional two-digit leg can be seen here.

MEET THE ‘BABY DRAGONS’

We are proudly presenting our ‘baby dragons’. From today, Postojna Cave visitors can meet our baby dragons face to face. The only baby olms in history that we have been following since they were still eggs are now finally on view. You can visit them in the company of our biologists and learn all about these animals that can regrow the injured parts of their body, go without food for at least eight years, and live to be 100. You may even find out the secret of their eternal youth.

Our olms are growing up! And so are we as we focus on research and on raising awareness of subterranean life and environmental conservation. Our efforts have been recognised by the company Generali Investments Slovenia, who was the first to take on the role of olm godparents, helping us set up a new aquarium, which is now home to two of the olms hatched back in 2016.