Although modern carnivores are a diverse group when it comes to diet, a typical carnivore feeds mostly on meat. Meat-eating carnivores tend to have a set of sharp-tipped teeth (carnassials), a characteristic of ancestral carnivores. Modified from molars, carnassials are specialized for slicing flesh. While meat is easier to digest, prey must be found, captured, and killed. Hunting collaboratively is sometimes more effective than hunting alone, and many large carnivores hunt in groups. Elaborate social behaviors have evolved around hunting, such as the dominance hierarchy in a pack of wolves. Even carnivores that do not hunt collaboratively, such as harbor seals and coatis, may live in social groups. Benefits of grouping may include sharing care of young or sharing defense of territory. Young carnivores must learn to hunt, which often means an extended training period. Carnivores have a high ratio of brain to body mass, allowing for the learning, coordination, and agility needed for hunting.

Mammals are named for their special milk-producing structures called mammary glands. A female mammal may have two (like humans) or as many as 18 mammary glands. Each gland is full of small spaces lined with milk-secreting cells that all drain into a nipple. Newborn mammals have an innate sucking reflex that stimulates the mother's mammary glands to release milk. Milk is a superfood for young mammals, containing a nourishing mix of fats, proteins, vitamins, minerals, and even immune-system chemicals. The first milk (colostrum) contains antibodies from the mother to protect against disease. As the offspring grows, milk changes to maintain the right balance of nutrients. Production of milk (lactation) makes most female mammals temporarily unable to get pregnant, resulting in natural gaps between offspring. The spacing of births benefits both the offspring and the mother in terms of survival. Mother mammals stop nursing (wean) their babies after several days or years, depending on the species and environmental conditions.