Most people associate caring for offspring with mothers.
In amphibians and reptiles, care is often absent, but when it occurs, it is usually provided by the female. But in the largest group of vertebrates, the bony fishes, female involvement in parental care is quite rare. However, in families that do exhibit some form of parental care, care is provided only by the male in about 50 percent, by both parents in about 18 percent, and only by the female in about 32 percent. Part of the explanation can be related to the mode of fertilization. In birds, mammals, and reptiles, fertilization is internal.