Vladivostok's Hidden Gems: Rare Tree Frogs Baffle Even the Experts

The Primorsky Aquarium in Vladivostok is home to several rare species of Theloderma, also called hole-in-the-tree frogs. These tiny amphibians, measuring just 1.5 to 4 centimetres, are so well camouflaged that even experts struggle to spot them. Their unique appearance and secretive nature make them a fascinating subject for a special educational project. In the wild, Theloderma frogs spend most of their lives hidden in tree hollows, rock crevices, and damp organic cavities. Their rough, textured skin—covered in strange growths—helps them blend into moss and bark, making them nearly invisible. Even skilled specialists can take up to a year to catch a glimpse of one in a controlled terrarium. Dmitry Serkov, a frog expert, once spent two years searching for a single species despite knowing it was there.

The aquarium currently houses five species: the marbled, starry, Chuangxi, Vietnamese, and brick-red Theloderma. Each lives in a carefully designed tank that mimics a tropical rainforest habitat. These frogs are not just masters of disguise—they are also agile swimmers and can glide between branches using the webbing on their toes.

The frogs are part of an educational programme called Growing Up in the Aquarium. Children take part in one-on-one sessions, learning about these elusive creatures and their natural environment. The project gives young visitors a rare chance to observe Theloderma frogs up close. Their extraordinary camouflage and natural behaviours offer a glimpse into the hidden world of tropical rainforests. The aquarium’s effort ensures these unusual amphibians remain both a scientific curiosity and an educational resource.