Chytridiomycosis is a disease caused by the fungus Batrachochytrium dendrobatidis. It is thought to be responsible for amphibian declines throughout the world and in some cases mass extinction. The fungus infects the outer layer of skin and may causes thickening of the epidermis, blistering and sloughing. The spores of the fungus are easily spread through water and thrive at cool temperatures. Some species have shown to be resistant to the disease.