The pigment that causes the dark coat of melanistic leopards and jaguars is melanin.
Melanin is produced by pigment-forming cells and absorbs much of the visible light that reaches the hair and skin. In melanistic leopards and jaguars, unusually high production of dark pigment makes the coat appear black or nearly black. Their normal rosettes usually have not vanished; they can remain visible as faint patterns in strong light.
The term “black panther” does not identify a separate species. It usually refers to a melanistic leopard, Panthera pardus, or melanistic jaguar, Panthera onca. The genetic basis differs between them: melanism in leopards is generally associated with a recessive allele, while in jaguars it is linked to a dominant allele involving the melanocortin-1 receptor pathway.
Melanin should not be confused with keratin, the structural protein in hair, claws and skin, or hemoglobin, the oxygen-carrying pigment in blood. Chlorophyll is the green pigment used by plants and algae in photosynthesis, making it unrelated to animal coat color.