2. Axolotl
This little Mexican salamander is closely related to the tiger salamander. However, the young of this species don’t undergo metamorphosis — like most amphibians — so the adults keep their gills. They are one of the few species of animal that can regenerate limbs. Because of this, they are used extensively in scientific research.
They are critically endangered due to urbanization in Mexico City and polluted water. There are also a number of non-native fish that have been introduced into their habitats. These fish eat their young and main food supply