A sea otter and her pup

A southern sea otter grooms while her pup nurses in Moss Landing, Calif. Sea otter moms are tough. Female sea otters expend enormous amounts of energy on pup-rearing, which they do without assistance from the pup's father. By the time the pup nears weaning at around 6 months old, mom’s daily energy demands are almost twice as high. When prey is limited, that makes mom’s job even harder. Photo by Lilian Carswell/USFWS.