sentences:  Within the concept of the modern ark, even projects of “frozen zoos” have been initiated, where gametes and embryos are stored under deep-freeze conditions in order to preserve them for a very long time.The mission of WAZA is to provide leadership and support for zoos, aquariums, and partner organizations of the world in animal care and welfare, conservation of biodiversity, environmental education and global sustainability.Indeed, zoos are at present rapidly evolving to serve in multiple ways as conservation centres.