Tanya Rankin has been studying platypus in the wild for four years, but she had never seen inside a platypus burrow. She tells bbc.co.uk how it felt to be the first scientist to witness it.

One of my greatest delights in my work is showing people from overseas these remarkable, wonderful animals. When Mike Salisbury, the producer, first saw a platypus up close he was thrilled. I knew it must be a special animal indeed to delight someone with so much experience with wild animals from all over the world. I have a great sense of pride in Australia's animals - especially the platypus- and to be able to show people this animal close-up is a great pleasure. I do feel privileged to be able to study these astonishing animals and even after several years of working with them they continue to amaze me with their adaptability, their resilience and their uniqueness.

My research focuses on the feeding biology of platypus. Seeing from the footage how these animals feed on the river bottom, rolling over rocks and sifting through gravel for insects made me think differently about how these animals actually fit into their environment and helped my research enormously. I was astounded at the sheer energy of the platypus- their quick movements, and physical strength in fossicking on the riverbed. I was particularly amazed to see just how they navigate in the river - the filming gave me such a sense of the 3- dimensionality of the river and just how effortlessly the platypus move through it. How the platypus cruised over and through the fissures and small caves in the rocks, skimming their soft bills over the rock surface picking up insects, how they used their sense of touch in their bill as well as electroreception in searching out food also amazed me. Even seeing the tiny chains of bubbles forced out of their fur by the pressure of the water gave me a better sense of how they dive, surface and maintain buoyancy.

Though the underwater side of things is closer to my area of research, attempting to film inside the burrows was the most satisfying aspect of my work on platypus both for the sheer hard work involved and the astounding results we got. It took several months effort radio-tracking female platypus to find a breeding female. Platypus normally use burrows close to the waters edge for sleeping but a breeding female will excavate a burrow several metres up the bank so I was looking for this clue that they were ready to lay their eggs. So I trudged along the riverbank, day after day, for months with my radiotracking receiver beeping away waiting, hoping for signs of a different kind of burrow. When I did finally get a female in a burrow several meters up the river bank I called in the cameraman and we stealthily and very carefully went to work. We waited until the mother had left the burrow and was well up river so our movements didn't disturb her while we inserted the video probe to view her offspring. I think that was the most agonising time - waiting for the mother to leave. I was used to working long and difficult hours in the dead of night, gritting my teeth against the cold but this was ridiculous. The silent, patient waiting was killing me - not to mention the cramps from laying still for so long on a cold night and the mosquitoes were horrendous. I was so tired all I wanted to do was sleep...then the mother left and we got the camera in the burrow. It is hard to describe the excitement I felt seeing inside a living platypus burrow - the sense of awe at being witness to this mystery for the first time ever.