Olm

 
Evolving in wet caves of Europe over 190 million years has given the Olm special adaptations to its lifestyle. It is entirely aquatic, can go for 10 years without food, and lives over 58 years. Not bad for a sightless salamander. Although it can see light and dark through its skin-covered eyes, it no longer needs them for finding food. Living in almost pure darkness, it has fine tuned its other senses to help it track prey and avoid predators. And living in streams and ponds in caves has allowed it to skip the last metamorphosis of amphibians from water-breathing gills to air-breathing lungs. It remains submerged for its entire life, using its tail to propel it through the dark, quiet water, like an eel.

Males are slightly smaller than females, at just under 230 mm, but otherwise they look similar on the outside. They are long and slender with small limbs. They have three toes on the forelegs and two on the hind legs. Chemical, electrical and mechanical receptors are present in the front of an Olm’s elongated head. These are some of the senses it uses to find prey, but not all. It also has a highly developed sense of taste and smell, which it can even use underwater. Its ears are tuned to hear both sound waves and ground vibrations. Finally, some experiments have shown that Olms may be able to orient themselves using Earth’s magnetic field.

Olms eat crabs, snails and insects. They can eat a lot at a time, then go for long periods of time without food by slowing their heart and metabolic rates. They are found in the caves and underground waterways of Italy, Croatia and Herzegovina.

Females lay between 5 and 70 eggs at a time. She will stay with them and protect them from predators until they are born. It takes about 6 months for the eggs to hatch. When they are born, they look exactly like adults, but smaller. Occasionally, the mother will retain the eggs inside her body and two fully formed young will be born instead of eggs. They will not become adults for up to 10 to 15 years. They can grow up to 12 inches long when mature.

The IUCN Redlist lists this species as vulnerable because of its fragmented range, and decreasing quality of habitat, especially due to water pollution.